Patent Publication Number: US-11377788-B2

Title: Supercritical fluid material finishing

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. Nonprovisional application Ser. No. 15/048,634, entitled Supercritical Fluid Material Finishing, filed Feb. 19, 2016 (the “634 Application”), now U.S. Pat. No. 10,480,123. The &#39;634 application claimed the benefit of U.S. Provisional Applications: (1) U.S. Provisional Patent Application 62/119,015, entitled Dyeing of Spooled Material with a Supercritical Fluid, filed on Feb. 20, 2015; (2) U.S. Provisional Patent Application 62/119,010 entitled Equilibrium Dyeing of Rolled Material with a Supercritical Fluid, filed on Feb. 20, 2015; (3) U.S. Provisional Patent Application 62/135,680, entitled Supercritical Fluid Treatment Process Variable Manipulation, filed on Mar. 19, 2015; and (4) U.S. Provisional Patent Application 62/296,980, entitled Supercritical Fluid Material Finishing, filed on Feb. 18, 2016. The entireties of the aforementioned applications are incorporated by reference herein. 
    
    
     TECHNICAL FIELD 
     Processing, dyeing, and treating of materials, such as fabric and or a yarn, with a supercritical fluid. 
     BACKGROUND 
     Traditional dyeing of materials relies on a large quantity of water, which can be detrimental to the fresh water supply and also result in undesired chemicals entering into the wastewater stream. As a result, use of a supercritical fluid has been explored as an alternative to the traditional water dye processes. However, a number of challenges have been encountered with the use of a supercritical fluid (“SCF”), such as carbon dioxide (“CO 2 ”), in a dyeing process. For example, the interaction of dye materials with a SCF, including the solubility, introduction, dispersion, circulation, deposition, and characterization of the interaction, have all posed problems to industrial-scale implementation of dyeing with a SCF. U.S. Pat. No. 6,261,326 (“&#39;326 patent”) to Hendrix et. al, filed Jan. 13, 2000 and assigned to North Carolina State University attempts to address previously explored solutions to the SCF and dye material interactions. The &#39;326 patent attempts to remedy the complications of the interaction with a separate preparation vessel for introducing the dye to a SCF and then transferring the solution of dye and SCF into a textile treatment system to dye a material. In the example of the &#39;326 patent, the dye is introduced into the vessel containing the material to be dyed in conjunction with the SCF, which can increase the complexity of the process and componentry of the system. 
     BRIEF SUMMARY 
     Methods are directed to finishing a target material with a material finish in a supercritical fluid carbon dioxide environment. Variables of the process are manipulated in different sequences to achieve a more efficient transfer of the material finish to the target material. The variables include, time, pressure, heat, internal flow rate, and CO 2  transfer within a pressure vessel. In an aspect, temperature is maintained above threshold values as pressure is decreased from an operating pressure to a transition pressure. The sequencing of variable manipulation allows for a greater uptake of material finish by the target material and less residual material finish deposited on surfaces of the system. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention is described in detail herein with reference to the attached drawing figures, wherein: 
         FIG. 1  is an exemplary illustration depicting the transfer of dye to a spooled material from a second material by way of a supercritical fluid, in accordance with an aspect hereof; 
         FIG. 2  is an exemplary illustration depicting the transfer of dye from a first material to a second material by way of a supercritical fluid, in accordance with an aspect hereof; 
         FIG. 3  depicts exemplary materials in a contacting arrangement for the perfusing of one of more materials finishes, in accordance with an aspect hereof; 
         FIG. 4  depicts exemplary materials in a non-contacting arrangement for the perfusing of one of more materials finishes, in accordance with an aspect hereof; 
         FIG. 5  depicts exemplary materials in a contacting arrangement, in accordance with an aspect hereof; 
         FIG. 6  depicts exemplary materials in a non-contacting arrangement, in accordance with an aspect hereof; 
         FIG. 7  depicts a series winding of two materials around a beam, in accordance with an aspect hereof; 
         FIG. 8  depicts contemporaneously wound materials around a beam, in accordance with an aspect hereof; 
         FIG. 9  depicts a temperature and pressure phase diagram for carbon dioxide, in accordance with an aspect hereof; 
         FIG. 10  depicts a flow chart representing an exemplary method of applying a dye to a spooled material using supercritical fluid, in accordance with an aspect hereof; 
         FIG. 11  depicts a flow chart representing an exemplary method of applying a material finish to a spooled material using supercritical fluid, in accordance with an aspect hereof; 
         FIG. 12  depicts a flow chart representing an exemplary method of applying a first material finish and a second material finish to a spooled material using supercritical fluid, in accordance with an aspect hereof; 
         FIG. 13  depicts a flow chart illustrating a method for dyeing material with a supercritical fluid, in accordance with an aspect hereof; 
         FIG. 14  depicts a flow chart illustrating another method for dyeing material with a supercritical fluid, in accordance with an aspect hereof; 
         FIG. 15  depicts a flow chart representing an exemplary method of applying a finish material to a target material, in accordance with aspects hereof; 
         FIG. 16  depicts a flow chart representing an exemplary method of scouring a material with supercritical fluid, in accordance with aspects hereof; 
         FIG. 17  depicts a flow chart representing an exemplary method of scouring and finishing (e.g., dyeing) a material in a continuous process, in accordance with aspects hereof; 
         FIGS. 18-22  depict relative variables during phases of supercritical dyeing, in accordance with aspects hereof; 
         FIGS. 23-26  depict relative variables during phases of supercritical scouring, in accordance with aspects hereof; and 
         FIG. 27  depicts a table of exemplary operating conditions for supercritical dyeing, in accordance with aspects hereof. 
     
    
    
     DETAILED DESCRIPTION 
     Methods are directed to finishing a target material with a material finish in a supercritical fluid carbon dioxide environment. Variables of the process are manipulated in different sequences to achieve a more efficient transfer of the material finish to the target material. The variables include, time, pressure, heat, internal flow rate within a pressure vessel, and exchange of the working substance (e.g., CO 2 ). In an aspect, temperature is maintained above threshold values as pressure is decreased from an operating pressure to a transition pressure. For example, the temperature and internal flow rates are maintained above respective threshold values until the density of the CO 2  passes a level in which dyestuff comes out of solution with the CO 2 . The sequencing of variable manipulation allows for a greater uptake of material finish by the target material and less residual material finish deposited on surfaces of the system. As a result, additional aspects contemplate eliminating or reducing the use of a cleaning process between target material finishing processes. 
     Materials, such as textiles (i.e. fabric, cloth) and/or spooled materials (e.g., yarn, thread, filament, cord, string, ribbon, and other continuous length materials), may be treated with a material finish to achieve a desired result, such as water resistance, abrasion resistance, breathability, and/or appearance (e.g., coloration). For example, the materials may be dyed to achieve a desired look. Dye is a substance used to add or change a color of a material, such as a textile, in an exemplary aspect. In an additional aspect, dye is a material finish, such as a durable water repellent finish (i.e., hydrophobic), fire resistant finish, anti-microbial finish, hydrophilic finish, and the like. In further aspects, dye is not a fabric finish other than a colorant and in other aspects dye is a fabric finish other than a colorant, when specifically indicated as such. Therefore, as used herein, a dye or the processes of dyeing is not limited to color or the process of coloring. Instead dye or dyeing includes a material finish or the process of finishing the target material. Dye materials, which are also referred to as dyestuff, may be particles of coloration that are natural or synthetic in formation. Traditionally, dye, together with a number of processing chemistries, are applied to a material through an aqueous solution, which may have varied acidic or basic (e.g., pH) conditions to enhance and/or achieve the dyeing process. However, this traditional dye process consumes large quantities of water and potentially discharges chemicals from the dyeing process in to the wastewater stream. 
     Supercritical fluid (“SCF”) carbon dioxide (“CO 2 ”) is a fluid state of CO 2  that exhibits characteristics of both a gas and a liquid. SCF CO 2  has liquid-like densities and gas-like low viscosities and diffusion properties. The liquid-like densities of SCF allows for SCF CO 2  to dissolve dye material and chemistries for eventual dyeing of a material. The gas-like viscosity and diffusion properties can allow for a faster dyeing time and faster dispersion of dye material than in a traditional water-based process, for example.  FIG. 9  provides a CO 2  pressure  604  and temperature  602  diagram that highlights the various phases of CO 2 , such as a solid phase  606 , a liquid phase  608 , a gas phase  610 , and a SCF phase  612 . As illustrated, CO 2  has a critical point  614  at about 304 degrees Kelvin (i.e. 87.53 degrees Fahrenheit, 30.85 Celsius) and 73.87 bar (i.e. 72.9 atm). Generally, at temperatures and pressures above the critical point  614 , CO 2  is in a SCF phase. 
     While examples herein refer specifically to SCF CO 2 , it is contemplated that additional or alternative compositions may be used at or near a supercritical fluid phase. Therefore, while specific reference will be made to CO 2  as a composition herein, it is contemplated that aspects hereof are applicable with alternative compositions and appropriate critical point values for achieving a SCF phase. 
     The use of SCF CO 2  in a dyeing process may be achieved using commercially available machines, such as a machine offered by DyeCoo Textile Systems BV of the Netherlands (“DyeCoo”). A process implemented in a traditional system includes placing an undyed material that is intended to be dyed into a vessel capable of being pressurized and heated to achieve a SCF CO 2 . A powdered dyestuff that is not integrally associated with a textile (e.g., loose powder) is maintained in a holding container. The dyestuff holding container is placed in the vessel with the undyed material such that the dyestuff is not contacting the undyed material prior to pressurizing the vessel. For example, the holding container physically separates the dyestuff from the undyed material. The vessel is pressurized and thermal energy is applied to bring CO 2  to a SCF (or near SCF) state, which causes the dyestuff to solubilize in the SCF CO 2 . In a traditional system, the dyestuff is transported from the holding container to the undyed material by the SCF CO 2 . The dyestuff is then diffused through the undyed material causing a dyeing of the undyed material until the SCF CO 2  phase is ceased. 
     Aspects herein relate to a concept of dye equilibrium as a manner of controlling a dye profile that results on a material. For example, if a first material has a dye profile that may be described as a red coloration and a second material has a dye profile that may be described by an absence of coloration (e.g., bleached or white), the concept of equilibrium dyeing with SCF CO 2  results in an attempted equalization between the two dye profiles such that at least some of the dyestuff forming the first dye profile is transferred from the first material to the second material. An application of this process includes using a sacrificial material having dyestuff contained thereon and/or therein (e.g., a dyed first material) that is used as a carrier for applying a specific dyestuff to a second material that is intended to be dyed by the dyestuff of the sacrificial material. For example, a first material and a second material may each have different resulting dye profiles from each other after a SCF CO 2  process is applied while also having a different dye profile from their respective initial dye profiles (e.g., first dye profile and second dye profile). This lack of true equilibrium may be desired. For example, if the first material is the sacrificial material that is merely intended to be a dye carrier, the process may be carried out until the second material achieves a desired dye profile, regardless of the resulting dye profile for the first material, in an exemplary aspect. 
     Another example of a dyeing process using SCF CO 2  may be referred to as an additive dyeing process. An example to aid in illustrating the additive dyeing process includes the first material having a dye profile that exhibits red coloration and the second material having a second dye profile that exhibits blue coloration. The SCF CO 2  is effective to result in dye profiles on the first material and the second material (and/or a third material) that exhibit purple coloration (e.g., red+blue=purple). 
     As before, it is contemplated that the first and second materials may achieve a common dye profile when the equilibrium dye process is allowed to mature. In additional aspects, it is contemplated that the first material and the second material result in different dye profiles from each other, but the resulting dye profiles are also different from the initial dye profile for each respective material. Further, it is contemplated that the first material may be a sacrificial dye transfer material while the second material is the material for which a target dye profile is desired. Therefore, the SCF CO 2  dye process may be performed until the second material achieves the desired dye profile regardless of the resulting dye profile of the first material. Further yet, it is contemplated that a first sacrificial material dye carrier having a first dye profile (e.g., red) and a second sacrificial dye carrier having a second dye profile (e.g., blue) may be placed into the system to cause a desired dye profile (e.g., purple) on a third material, in an exemplary aspect. As can be appreciated, any combination and number of materials, dye profiles, and other contemplated variables (e.g., time, SCF CO 2  volume, temperature, pressure, material composition, and material type) may be altered to achieve results contemplated herein. 
     Aspects herein contemplate dyeing (e.g., treating with material finishes) of one or more materials using SCF CO 2 . The concept of two or more materials used in conjunction with each other is contemplated in aspects hereof. Further, the use of one or more materials having integral dyestuff that are not intended for traditional post-processing utilization (e.g., apparel manufacturing, shoe manufacturing, carpeting, upholstery), which may be referred to as sacrificial material or as dye carriers, are contemplated as being introduced in the system. Further, it is contemplated that any dye profile may be used. Any combination of dye profiles may be used in conjunction with one another to achieve any desired dye profile in one or more materials. Additional features and process variable for disclosed methods and systems will be provided herein. 
     Achieving a desired dye profile on a material may be influenced by a number of factors. For example, if there are 50 kg of a first material (e.g., spooled or rolled material) and 100 kg of a second material, the resulting dye profile per weight of the first material may be expressed as 1/3 the original color/intensity/saturation of the first dye profile when the second material original dye profile is absent of dye. Alternatively, with the same proportions of material but the original second dye profile having a comparable saturation/intensity as the first dye profile, but with a different coloration, the first dye profile may be expressed as 1/3X+1/3Y where X is the original first dye profile and Y is the original second dye profile (i.e. weight of the first material/weight of all materials). From the second material perspective using the two previous examples, the resulting dye profiles may be (2/3X)/2 for the first example and (2/3X+2/3Y)/2 (i.e. [weight of the first material/weight of all materials]*[weight of the first material/weight of the second material]). The previous examples are for illustration purposes only as it is contemplated that a number of additional factors are also relevant, such as yardage per kilogram, material composition, dye process length, temperature, pressure, time, material porosity, material density, winding tension of the material, and other variables that may be represented by an empirical value(s). However, the preceding is intended to provide an understanding of the intended equilibrium dyeing process to supplement the aspects provided herein. As such, the provided examples and values are not limiting but merely exemplary in nature. 
     Referring now to  FIG. 1 , an exemplary illustration depicting the transfer of dye  100  from a second material  102  to a spooled material  104  by way of a SCF CO 2 , in accordance with aspects hereof. A material introduced to the dyeing process with SCF CO 2  may be any material, such as compositions (e.g., cotton, wool, silk, polyester, and/or nylon), substrates (e.g., fabrics and/or yarns), products (e.g., footwear and/or garments), and the like. In an exemplary aspect, the second material  102  is a polyester material having a first dye profile comprised of dye material  108 . A dye profile is a dye characteristic or material finish characteristic, which may be defined by a color, intensity, shade, dyestuff type(s), and/or chemical composition. It is contemplated that a material for which there is no substantial dyestuff (e.g., no unnaturally occurring coloration from a dyeing method or other material finishes applied thereon) also has a dye profile that describes the absence of dye. Therefore, regardless of the coloration, finish, or dye associated with a material, all materials have a dye profile. Stated differently, all materials, irrespective of color/material finish processes performed (or not performed), has a dye profile. For example, all materials have a starting coloration regardless of if a dye process has been performed on the material. 
     The second material  102  has a first surface  120 , a second surface  122 , and a plurality of dye material  108 . The dye material  108 , which may be a composition/mixture of dyestuffs, is depicted as granular elements for discussion purposes; however, in actuality the dye material  108  may not be individually identifiable at the macro level from the underlying substrate of a material. Also, as will be discussed hereinafter, it is contemplated that the dyestuff may be integral with the material. Integral dyestuff is dyestuff that is chemically or physically bonded with the material. Integral dyestuff is compared to non-integral dyestuff, which is dyestuff that is not chemically or physically coupled with a material. An example of a non-integral dyestuff includes dry powdered dyestuff sprinkled and brushed on the surface of a material such that the dyestuff is removed with minimal mechanical effort. 
     At  FIG. 1 , the SCF CO 2    106  is graphically illustrated as arrows for discussion purposes only. In actuality, the SCF CO 2  is not separately identifiable at a macro level even though it is depicted as such in  FIG. 1 . Further yet, a dye material  112  and  116  is depicted as being transferred by SCF CO 2    110  and  118  respectively, but as indicated, this illustration is for discussion purposes and not a scaled representation of actuality. 
     With respect to  FIG. 1 , the SCF CO 2    106  is introduced to the second material  102 . The initial introduction of SCF CO 2    106  is without dye material associated (e.g., without dyestuff dissolved therein). The SCF CO 2    106  passes through the second material  102  from the first side  120  to the second side  122 , in an exemplary aspect. As the SCF CO 2    106  passes through the second material  102 , dye material  108  (e.g., dyestuff) for the second material  102  becomes associated (e.g., dissolved) with the SCF CO 2 , which is depicted as the dye material  112  in connection with SCF CO 2    110 . The second material  102  is depicted as having a first dye profile, which may be caused by the dye material  108  of the second material  102 . Alternatively, it is contemplated that the initial introduction (or at any time) of SCF CO 2  may transport dyestuff from a source (e.g., holding container) to the second material  102  to augment the dye profile of the second material while also augmenting the dye profile of the spooled material  104  with the dyestuff of the source and the second material  102 , in an exemplary aspect. 
     The spooled material may be a continuous yarn-like material that is effective for use in weaving, knitting, braiding, crocheting, sewing, embroidering, and the like. Non-limiting examples of spooled material include yarn, thread, rope, ribbon, filament, and cord. It is contemplated that the spooled material may be wound about a spool (e.g., conical or cylindrical) or the spooled material may be wound about itself without a secondary support structure helping form the resulting wound shape. The spooled material may be organic or synthetic in nature. The spooled material may be a plurality of individual collections of material or a singular collection of material. 
     In  FIG. 1 , the spooled material  104  has a first surface  124  and a second surface  126 . The spooled material also is depicted as having a second dye profile with dye material  114 . The dye material  114  may be dyestuff transferred by the SCF CO 2  having passed through the second material  102  and/or it is dyestuff associated with the spooled material  104  in a previous operation, in an exemplary aspect. 
     As such,  FIG. 1  depicts a SCF CO 2  dyeing operation in which SCF CO 2  passes through the second material  102  from the first side  120  to the second side  122  while transferring (e.g., such as dissolving dyestuff in the SCF CO 2 ) dyestuff from the second material, as depicted by dye material  112  being transported by the SCF CO 2    110 . The spooled material  104  receives the SCF CO 2  (e.g.,  110 ) on the first side  124 . The SCF CO 2  passes through the spooled material  104  while allowing dye material (e.g.,  114 ) to dye the spooled material  104 . The dye material dyeing the spooled material  104  may be dye material from the second material  102 , in an exemplary aspect. It is further contemplated that the dye material dyeing the spooled material  104  may be dye material from additional material layers or sources. Further, the SCF CO 2  may pass through the spooled material  104  (e.g., SCF CO 2    118 ) while transferring dye material (e.g.,  116 ) therewith. This dye material  116  may be deposited with another material layer and/or the second material  102  layer. As can be appreciated, this may be a cycle in which equilibrium of dye material is achieved on the different material layers as the SCF CO 2  repeatedly passes through the material layers. Eventually, it is contemplated the dye material  108 ,  112 ,  114 , and  116  may be indistinguishable and/or result in an indistinguishable dye profile among the different materials, in an exemplary aspect. Stated differently, as each of the various dyestuff has a different solubility within the SCF, the flow of the SCF through the various materials picks up and deposits the dyestuff creating a homogeneous blend of the dyestuff at a macro level (e.g., to the human eye). This cycle may continue until the SCF is removed from the cycle process, such as at a state change of the CO 2  from a SCF state. 
       FIG. 1  is exemplary in nature and is intended to serve as an illustration of the process without being depicted at scale. Therefore, it is understood that in actuality the dyestuff (i.e., dye material), the materials, and the SCF CO 2  may instead be seemingly indistinguishable to a common observer at a macro scale without special equipment, in an exemplary aspect. 
     Referring now to  FIG. 2 , an exemplary illustration depicting the transfer of dye  101  from a first material  1102  to a second material  1104  by way of a SCF CO 2 , in accordance with aspects hereof. A material introduced to the equilibrium dyeing with SCF CO 2  may be any material, such as compositions (e.g., cotton, wool, silk, polyester, and/or nylon), substrates (e.g., fabrics and/or yarns), products (e/.g., footwear and/or garments), and the like. In an exemplary aspect, the first material  1102  is a polyester material having a first dye profile comprised of dye material  1108 . The first material  1102  has a first surface  1120 , a second surface  1122 , and a plurality of dye material  1108 . The dye material  1108 , which may be a composition/mixture of dyestuffs, is depicted as granular elements for discussion purposes; however, in actuality the dye material  1108  may not be individually identifiable at the macro level from the underlying substrate of a material. Also, as will be discussed hereinafter, it is contemplated that the dyestuff is integral with the material. An integral dyestuff is dyestuff that is chemically or physically bonded with the material. Integral dyestuff is compared to non-integral dyestuff, which is dyestuff that is not chemically or physically coupled with a material. An example of a non-integral dyestuff includes dry powdered dyestuff sprinkled and brushed on the surface of a material such that the dyestuff is removed with minimal mechanical effort. 
     At  FIG. 2 , the SCF CO 2    1106  is graphically illustrated as arrows for discussion purposes only. In actuality, the SCF CO 2  is not separately identifiable at a macro level as depicted in  FIG. 2 . Further yet, a dye material  1112  and  1116  is depicted as being transferred by SCF CO 2    1110  and  1116  respectively, but as indicated, this illustration is for discussion purposes and not a scaled representation of actuality. 
     With respect to  FIG. 2 , the SCF CO 2    1106  is introduced to the first material  1102 . The initial introduction of SCF CO 2    1106  is without dye material associated (e.g., without dyestuff dissolved therein). The SCF CO 2    1106  passes through the first material  1102  from the first side  1120  to the second side  1122 , in an exemplary aspect. As the SCF CO 2    1106  passes through the first material  1102 , dye material  1108  (e.g., dyestuff) for the first material  1102  becomes associated (e.g., dissolved) with the SCF CO 2 , which is depicted as the dye material  1112  in connection with SCF CO 2    1110 . The first material  1102  is depicted as having a first dye profile, which may be caused by the dye material  1108  of the first material  1102 . Alternatively, it is contemplated that the initial introduction (or at any time) of SCF CO 2  may transport dyestuff from a source (e.g., holding container) to the first material  1102  to augment the dye profile of the first material while also augmenting the dye profile of the second material  1104  with the dyestuff of the source and the first material  1102 , in an exemplary aspect. 
     The second material  1104  has a first surface  1124  and a second surface  1126 . The second material also is depicted as having a second dye profile with dye material  1114 . The dye material  1114  may be dyestuff transferred by the SCF CO 2  having passed through the first material  1102  and/or it is dyestuff associated with the second material  1104  in a previous operation, in an exemplary aspect. 
     As such,  FIG. 2  depicts a SCF CO 2  dyeing operation in which SCF CO 2  passes through the first material  1102  from the first side  1120  to the second side  1122  while transferring (e.g., such as dissolving dyestuff in the SCF CO 2 ) dyestuff from the first material, as depicted by dye material  1112  being transported by the SCF CO 2    1110 . The second material  1104  receives the SCF CO 2  (e.g.,  1110 ) on the first side  1124 . The SCF CO 2  passes through the second material  1104  while allowing dye material (e.g.,  1114 ) to dye the second material  1104 . The dye material dyeing the second material  1104  may be dye material from the first material  1102 , in an exemplary aspect. It is further contemplated that the dye material dyeing the second material  1104  may be dye material from additional material layers or sources. Further, the SCF CO 2  may pass through the second material  1104  (e.g., SCF CO 2    1118 ) while transferring dye material (e.g.,  1116 ) therewith. This dye material  1116  may be deposited with another material layer and/or the first material  1102  layer. As can be appreciated, this may be a cycle in which equilibrium of dye material is achieved on the different material layers as the SCF CO 2  repeatedly passes through the material layers. Eventually, it is contemplated the dye material  1108 ,  1112 ,  1114 , and  1116  may be indistinguishable and/or result in an indistinguishable dye profile among the different materials, in an exemplary aspect. Stated differently, as each of the various dyestuff has a different solubility within the SCF, the flow of the SCF through the various materials picks up and deposits the dyestuff creating a homogeneous blend of the dyestuff at a macro level (e.g., to the human eye). This cycle may continue until the SCF is removed from the cycle process, such as at a state change of the CO 2  from a SCF state. 
       FIG. 2  is exemplary in nature and is intended to serve as an illustration of the process without being depicted at scale. Therefore, it is understood that in actuality the dyestuff (i.e., dye material), the materials, and the SCF CO 2  may instead be seemingly indistinguishable to a common observer at a macro scale without special equipment, in an exemplary aspect. 
     Further, as will be provided herein, aspects contemplate a dyestuff integral to a material. A dyestuff is integral to a material when it is physically or chemically bonded with the material, in an example. In another example, dyestuff is integral to the material when the dyestuff is homogenized on the material. The homogenization of dyestuff is in contrast to a material on which dyestuff is applied in a non-uniform manner, such as if a dyestuff is merely sprinkled or otherwise loosely applied to the material. An example of integral dyestuff with a material is when dyestuff is embedded and maintained within the fibers of a material, such as when dyestuff perfuses a material. 
     The term “perfuse,” as used herein, is to coat, permeate, and/or diffuse surface finishes, such as dyestuff over and/or throughout a material. The perfusing of a material with dyestuff occurs in a pressure vessel, such as an autoclave, as is known in the art. Further, the SCF and dyestuff dissolved in the SCF may be circulated within the pressure vessel with a circulation pump, as is also known in the art. The circulation of SCF within the pressure vessel by a pump causes the SCF to pass through and around a material within the pressure vessel to cause dissolved dyestuff to perfuse the material. Stated differently, when a target material is perfused with SCF CO 2  having dyestuff (e.g., finish material) dissolved therein, the dyestuff is deposited on one or more portions of the target material. For example, a polyester material, when exposed to the conditions suitable for forming SCF CO 2 , may “open” up allowing for portions of the dyestuff to remain embedded with the polyester fibers forming the polyester material. Therefore, adjusting the heat, pressure, circulation flow, and time affects the SCF, the dyestuff, and the target material. The variables all taken in combination, when the SCF CO 2  perfuses the target material, a deposit of dyestuff throughout the material may occur. 
       FIG. 3  depicts a material holding element  204 , supporting a plurality of spooled materials  206  and a second material  208 , in accordance with aspects hereof. The plurality of spooled materials  206 , in this example has a first dye profile. The first dye profile may be a profile that is lacking coloration or other surface finishes other than the natural state of the material, in an exemplary aspect. The plurality of spooled materials  206  may be a target material, a material intended for use in a commercial good, such as apparel or footwear. The second material  208  may be a sacrificial material having integral dyestuff. For example, the second material  208  may be a previously dyed (or otherwise treated) material. 
     In the example depicted in  FIG. 3 , which is in contrast to  FIG. 4  to be discussed hereinafter, the second material  208  is in physical contact with the spooled material  206 . In this example, a surface of the second material  208  is contacting a surface of the spooled material  206 . The physical contact or close proximity provided by the contact, in an exemplary aspect, provides for an efficient transfer of dyestuff from the second material  208  to the spooled material  206  in the presence of SCF. Further, physical contact of the materials exposed to a SCF for dyeing purposes allows for, in an exemplary aspect, efficient use of space in a pressure vessel so that dimensions (e.g., roll length of a material) of a material may be maximized. 
     As depicted in  FIG. 3  for exemplary purposes, the second material  208  is significantly smaller in volume than the spooled material  206 . In this example, the spooled material  206  is the target material; therefore, a maximization of volume for target material may be desired. As some pressure vessels have limited volume, a portion of that limited volume consumed by a sacrificial material limits the volume useable by a target material. As such, in an exemplary aspect, a sacrificial (or plurality of sacrificial materials) are of a smaller volume (e.g., yardage) than a target material when positioned in a common pressure vessel. Further, while an exemplary material holding element  204  is depicted, it is contemplated that alternative configurations of a holding element may be implemented. 
       FIG. 4  depicts a material holding element, also supporting a spooled material  207  and a second material  209 , in accordance with aspects hereof. While the spooled material  207  and the second material  209  are depicted on a common holding element, it is contemplated that physically separate holding elements may be used in alternative exemplary aspects. The spooled material  207  has a first dye profile and the second material  209  has a second dye profile. In particular, at least one of the spooled material  207  or the second material  209  has an integral dyestuff. To the contrary of  FIG. 3  in which close proximity or physical contact is depicted with the multiple materials, the materials of  FIG. 4  are not in direct contact with one another. The lack of physical contact, in an exemplary aspect, allows for the efficient substitution and manipulation of at least one material without significant physical manipulation of the other material(s). For example, if the second material  209  has a dye profile having a first coloration is processed with the spooled material  207  such that at least some of the dyestuff of the second material perfuses the spooled material  207  in a SCF dyeing process, the second material  209  may be removed and substituted with a third material having a different dye profile (e.g., a material treatment such as DWR) that is preferred to be perfused to the spooled material  207  subsequent to the dyestuff of the second material  209 . Stated differently, the physical relationship depicted and generally discussed with  FIG. 4  may be efficient in manufacturing and processing as individual manipulation of the materials may be accomplished. 
     While the spooled material  207  and the second material  209  are depicted on a common material holding element  204 , it is contemplated that the spooled material  207  is on a first holding element and the second material  209  is on a second holding element that is different from the first holding element, in an exemplary aspect. 
     While only two materials are depicted in  FIGS. 3 and 4 , it is understood that any number of materials may be simultaneously exposed to a SCF (or near SCF). For example, it is contemplated that two or more sacrificial materials having integral dyestuff are placed within a common pressure vessel with a target material intended to be perfused with the dyestuff of the sacrificial materials. Further, it is contemplated that a quantity of the materials is not limited to those proportions depicted in  FIG. 3 or 4 . For example, it is contemplated that a target material may be of much greater volume than a sacrificial material. Further, it is contemplated that a volume of sacrificial material may be adjusted to accomplish a desired dye profile of the target material(s). For example, depending on the dye profile of the sacrificial material (e.g., concentration, coloration, etc.) and the desired dye profile for target material in addition to the volume of the target material, the amount of sacrificial material may be adjusted to achieve a desired SCF dyeing result. Similarly, it is contemplated that the dye profile of the second material (or first material) is adjusted based on a desired dye profile and/or a volume of material included in the dyeing process. 
       FIG. 5  depicts a material holding element, such as a beam  1204 , supporting a first material  1206  and a second material  1208 , in accordance with aspects hereof. The first material  1206 , in this example has a first dye profile. The first dye profile may be a profile that is lacking coloration other than the natural state of the material, in an exemplary aspect. The first material  1206  may be a target material, a material intended for use in a commercial good, such as apparel or footwear. The second material  1208  may be a sacrificial material having integral dyestuff. For example, the second material  1208  may be a previously dyed (or other treatment) material. 
     In the example depicted in  FIG. 5 , which is in contrast to  FIG. 6  to be discussed hereinafter, the second material  1208  is in physical contact with the first material  1206 . In this example, a surface of the second material  1208  is contacting a surface of the first material  1206 . The physical contact or close proximity provided by the contact, in an exemplary aspect, provides for an efficient transfer of dyestuff from the second material  1208  to the first material  1206  in the presence of SCF. Further, physical contact of the materials exposed to a SCF for dyeing purposes allows for, in an exemplary aspect, efficient use of space in a pressure vessel so that dimensions (e.g., roll length of a material) of a material may be maximized. 
     As depicted in  FIG. 5  for exemplary purposes, the second material  1208  is significantly smaller in volume than the first material  1206 . In this example, the first material  1206  is the target material; therefore, a maximization of volume for target material may be desired. As some pressure vessels have limited volume, a portion of that limited volume consumed by a sacrificial material limits the volume useable by a target material. As such, in an exemplary aspect, a sacrificial (or plurality of sacrificial materials) are of a smaller volume (e.g., yardage) than a target material when positioned in a common pressure vessel. While the second material  1208  is depicted on an outward location of the beam  1204  relative to the first material  1206 , it is contemplated that the sacrificial material may be positioned more inwardly on the beam  1204  relative to a target material. Further, while an exemplary beam  1204  is depicted, it is contemplated that alternative configurations of a holding element may be implemented. 
       FIG. 6  depicts a material holding element, such as the beam  1204 , also supporting a first material  1207  and a second material  1209 , in accordance with aspects hereof. While the first material  1207  and the second material  1209  are depicted on a common holding element, it is contemplated that different holding elements may be used in alternative exemplary aspects. The first material  1207  has a first dye profile and the second material  1209  has a second dye profile. In particular, at least one of the first material  1207  or the second material  1209  has an integral dyestuff. To the contrary of  FIG. 5  in which close proximity or physical contact is depicted with the multiple materials, the materials of  FIG. 6  are not in direct contact with one another. The lack of physical contact, in an exemplary aspect, allows for the efficient substitution and manipulation of at least one material without significant physical manipulation of the other material(s). For example, if the second material  1209  has a dye profile having a first coloration is processed with the first material  1207  such that at least some of the dyestuff of the second material perfuses the first material  1207  in a SCF dyeing process, the second material  1209  may be removed and substituted with a third material having a different dye profile (e.g., a material treatment such as DWR) that is preferred to be perfused to the first material  1207  subsequent to the dyestuff of the second material  1209 . Stated differently, the physical relationship depicted and generally discussed with  FIG. 6  may be efficient in manufacturing and processing as individual manipulation of the materials may be accomplished, in an exemplary aspect. 
     While the first material  1207  and the second material  1209  are depicted as having a similar volume of material, it is contemplated that the first material  1207  may have a substantially greater volume of material than the second material  1209 , which may serve as a sacrificial material in an exemplary aspect. Further, while the first material  1207  and the second material  1209  are depicted on a common holding element, it is contemplated that the first material  1207  is on a first holding element and the second material  1209  is on a second holding element that is different from the first holding element, in an exemplary aspect. 
     While only two materials are depicted in  FIGS. 5 and 6 , it is understood that any number of materials may be simultaneously exposed to a SCF (or near SCF). For example, it is contemplated that two or more sacrificial materials having integral dyestuff are placed within a common pressure vessel with a target material intended to be perfused with the dyestuff of the sacrificial materials. Further, it is contemplated that a quantity of the materials is not limited to those proportions depicted in  FIG. 5 or 6 . For example, it is contemplated that a target material may be of much greater volume than a sacrificial material. Further, it is contemplated that a volume of sacrificial material may be adjusted to accomplish a desired dye profile of the target material(s). For example, depending on the dye profile of the sacrificial material (e.g., concentration, coloration, etc.) and the desired dye profile for target material in addition to the volume of the target material, the amount of sacrificial material may be adjusted to achieve a desired SCF dyeing result. Similarly, it is contemplated that the dye profile of the second material (or first material) is adjusted based on a desired dye profile and/or a volume of material included in the dyeing process. 
     As has been illustrated in  FIGS. 5 and 6  and will be illustrated in  FIGS. 7 and 8 , various engagements of the first material and the second material about the holding device are contemplated. As previously provided, the first material  1206  and/or the second material  1208  may be any material fabric that is knit, woven, or otherwise constructed. They may be formed from any material organic or synthetic. They may have any dye profile, in an exemplary aspect. The dye profile may comprise any dye type formed from any dyestuff. In an exemplary aspect, the first material  1206  and the second material  1208  are a polyester woven material. 
     The SCF CO 2  allows the polyester to be dyed with a modified dispersed dyestuff. This occurs because the SCF CO 2  and/or the conditions causing the SCF state of CO 2  result in the polyester fibers of the materials to swell, which allows the dyestuff to diffuse and penetrate the pore and capillary structures of the polyester fibers. It is contemplated that reactive dye may similarly be used when one or more of the materials is cellulosic in composition. In an exemplary aspect, the first material  1206  and the second material  1208  are formed from a common material type such that dyestuff is effective for dyeing both materials. In an alternative aspect, such as when one of the materials is sacrificial in nature as a dye carrier, the dyestuff may have a lower affinity for the sacrificial material than the target material, which could increase the speed of SCF CO 2  dyeing. An example may include the first material being cellulosic in nature and the second material being a polyester material and the dyestuff associated with the first material being a dispersed dye type such that the dyestuff has a greater affinity for the polyester material (in this example) over the first material. In this example, a reduced dyeing time may be experienced to achieve a desired dye profile of the second material. 
       FIG. 10  depicts a flow chart  300  of an exemplary method of dyeing a spooled material, such as those depicted in  FIGS. 1, 3, and 4 , in accordance with aspects hereof. At a block  302 , a plurality of spooled materials and a second material are positioned in a pressure vessel. In an exemplary aspect, the spooled material may be maintained on a securing apparatus that allows for a plurality of spooled materials to be positioned in the pressure vessel at a common time. Additionally, it is contemplated that the securing apparatus is effective to position the spooled materials in an appropriate position relative to the internal walls of the pressure vessel as well as the relative to other spooled materials. In an exemplary aspect, avoiding contact with the internal walls of the pressure vessel by a material to be perfused with a material finish allows for the material to be perfused with the material finish. As previously discussed, the spooled materials may be wound about a beam prior to being positioned in the vessel. The materials may be positioned within the vessel by moving the materials as a common grouping into the pressure vessel. Also, it is contemplated that the material may be maintained on the securing apparatus in a variety of manners (e.g., in a vertical, in a stacked, in a horizontal, and/or in an offset manner). Further, it is contemplated that the materials may be maintained on different securing devices and positioned in a common pressure vessel. 
     At a block  304 , the pressure vessel may be pressurized. In an exemplary aspect, the materials are loaded into the pressure vessel and then the pressure vessel is sealed and pressurized. In order to maintain inserted CO 2  in the SCF phase, the pressure, in an exemplary aspect, is raised above the critical point (e.g., 73.87 bar). 
     Regardless of how the pressure vessel is brought to pressure, at a block  306 , SCF CO 2  is introduced into the pressure vessel. This SCF CO 2  may be introduced by transitioning CO 2  maintained in the pressure vessel from a first state (i.e., liquid, gas, or solid) into a SCF state. As know, the state change may be accomplished by achieving a pressure and/or temperature sufficient for a SCF phase change. It is contemplated that one or more heating elements are engaged to raise the internal temperature of the pressure vessel to a sufficient temperature (e.g., 304 K, 30.85 C). One or more heating elements may also heat the CO 2  as (or before) it is introduced into the pressure vessel, in an exemplary aspect. 
     At a block  308 , the SCF CO 2  is passed through each of the plurality of spooled materials and the second material. While the SCF CO 2  passes through the materials, which may have different dye profiles, dyestuffs is transferred between the materials and perfuse the material(s). In an exemplary aspect, the dyestuff is dissolved in the SCF CO 2  such that the SCF CO 2  serves as a solvent and carrier for the dyestuff. Further, because of the temperature and pressure of the SCF CO 2 , the materials may alter (e.g., expand, open, swell), temporarily, to be more receptive to dyeing by the dyestuff. 
     It is contemplated that the passing of SCF CO 2  is a cycle in which the SCF CO 2  is passed through the materials multiple times, such as in a closed system with a circulation pump, in an exemplary aspect. It is this circulation that may help achieve the dyeing. In an aspect, the SCF is circulated through the materials for a period of time (e.g., 60 minutes, 90 minutes, 120 minutes, 180, minutes, 240 minutes) and then the SCF CO 2  is allowed to change state (e.g., to a liquid CO 2 ) by dropping temperature and/or pressure. After changing state of the CO 2  from SCF state, the dyestuff is no longer soluble in the non-SCF CO 2 , in an exemplary aspect. For example, dyestuff may be soluble in SCF CO 2 , but when the CO 2  transitions to liquid CO 2 , the dyestuff is no longer soluble in the liquid CO 2 . 
     At a block  310 , the plurality of spooled materials and the second material are extracted from the pressure vessel. In an exemplary aspect, the pressure within the pressure vessel is reduced to near atmospheric pressure and the CO 2  is recaptured from the pressure vessel for potential reuse in subsequent dyeing operations. In an example, a securing apparatus securing the materials may be moved out of the vessel after a desired dye profile is achieved for one or more of the materials. 
     While specific steps are discussed and depicted in  FIG. 10 , it is contemplated that one or more additional or alternative steps may be introduced to achieve aspects hereof. Further, it is contemplated that one or more of the listed steps may be omitted altogether to achieve aspects provided herein. 
       FIG. 11  depicts a flow diagram  400  depicting an exemplary method of applying a material finish to a spooled material with a sacrificial material, in accordance with aspects herein. At a block  402 , a sacrificial material having a surface finish and a plurality of spooled materials are positioned in a common pressure vessel. As previously discussed, the positioning may be manual or automated. The positioning may also be accomplished by used of moving a common securing apparatus to which the sacrificial material and/or one or more of the plurality of spooled materials are secured for positioning. It is contemplated that the sacrificial material is in contact with or physically separated from the spooled material when being positioned in the pressure vessel. 
     As previously discussed, it is contemplated that the material finish of the sacrificial material may be a colorant (e.g., dyestuff), a hydrophilic finish, a hydrophobic finish, and/or an anti-microbial finish. As will be illustrated in  FIG. 12  hereinafter, it is contemplated that multiple sacrificial materials may be positioned within the pressure vessel at a common time with the plurality of spooled materials. Alternatively, it is contemplated that a sacrificial material may include more than one material finish intended to be applied to the plurality of spooled materials. For example, both a colorant and a hydrophilic finish may be maintained by the sacrificial material and applied to the spooled materials through the perfusing of SCF, in an exemplary aspect. 
     At a block  404 , carbon dioxide is introduced into the pressure vessel. The CO 2  may be in a liquid or gas state when it is introduced. Further, it is contemplated that the pressure vessel is enclosed at the time of the CO 2  introduction to maintain the CO 2  within the pressure vessel. The pressure vessel may be at atmospheric pressure when the CO 2  is introduced. Alternatively, the pressure vessel may be above or below atmospheric pressure when the CO 2  is introduced. 
     At a block  406 , the pressure vessel is pressurized allowing the introduced CO 2  to achieve a SCF (or near) state. Additionally, it is contemplated that thermal energy is applied to (or within) the pressure vessel to aid in achieving the SCF state of the CO 2 . As discussed hereinabove, the state diagram of  FIG. 9  depicts a trend between temperature and pressure to achieve a SCF state. In an aspect, the pressure vessel is pressurized to at least 73.87 bar. This pressurization may be accomplished by injection of atmospheric air and/or CO 2  until the internal pressure of the pressure vessel reaches the desired pressure, such as at least the critical point pressure of CO 2 . 
     At a block  408 , the plurality of spooled materials are perfused with at least a portion of the material finish from the sacrificial material. The material finish is transferred to the plurality of spooled materials by way of the SCF CO 2 . As discussed previously, the SCF CO 2  serves as a transportation mechanism for the material finish from the sacrificial material to the plurality of spooled materials. This may be assisted by circulating, such as by a circulation pump, the SCF within the pressure vessel so that it perfuses both the sacrificial material and the plurality of spooled materials. It is contemplated that the material finish may dissolve, at least partially, within the SCF allowing for their release from being bound with the sacrificial material to being deposited on/within the plurality of spooled materials. To ensure consistent application of the material finish to the plurality of spooled materials, the material finish may be integral to the sacrificial material, which ensures the intended amount of material finish is introduced within the pressure vessel. The transfer of the material finish may continue until a sufficient amount of the material finish perfuses the spooled materials. 
     While specific reference in  FIG. 11  is made to one or more steps, it is contemplated that one or more additional or alternative steps may be implemented while achieving aspects provided herein. As such, blocks may be added or omitted while still staying within the scope hereof. 
       FIG. 12  depicts a flow diagram  500  illustrating a method of applying at least two material finishes to a spooled material from a first and a second sacrificial material, in accordance with aspects herein. A block  502  depicts a step of positioning a spooled material, a first sacrificial material and a second sacrificial material in a common pressure vessel. The first sacrificial material having a first material finish and the second sacrificial material having a second material finish. For example, as provided above, it is contemplated that the first material finish is a first dye profile and the second material finish is a second dye profile, that when perfused with the spooled material, results in a third dye profile. The previous example applies here as well where the first dye profile is a red colorant and the second dye profile is a blue colorant such that when both the red and blue colorants perfuse the spooled material, the spooled material assumes a purple coloration. In an alternative example, the first material finish may be an anti-bacterial finish and the second material finish may be a hydrophobic material finish, such that the spooled material acquires both material finishes in a common application process, which reduces finishing time. While specific material finishes are provided in combination, it is recognized that any combination may be exposed to the SCF at a common time for application to the spooled material. 
     While a first and a second sacrificial material are discussed, any number of sacrificial materials may be provided. Further, it is contemplated that a quantity of the first sacrificial material and a quantity of the second sacrificial material are different depending on a desired amount of each material finish desired to be applied to the spooled material. Further, it is contemplated that the sacrificial materials will also maintain a portion of the material finish from the other materials within the pressure vessel. Therefore, it is contemplated the volume of all materials, include sacrificial, are considered when determining a quantity of surface finish to be inserted in the pressure vessel. 
     At a block  504 , the pressure vessel is pressurized such that CO 2  within the pressure vessel achieves a SCF state therein. The SCF is then effective to administer the material finish of the first sacrificial material and the second material finish of the second material to the spooled material, as depicted in a block  506 . 
     While specific reference in  FIG. 12  is made to one or more steps, it is contemplated that one or more additional or alternative steps may be implemented while achieving aspects provided herein. As such, blocks may be added or omitted while still staying within the scope hereof. 
       FIG. 7  depicts a first exemplary winding  1300  of multiple materials having surface contact with one another on a beam  1204  for equilibrium dyeing, in accordance with aspects hereof. The winding  1300  is comprised of the beam  1204 , the first material  1206 , and the second material  1208 . The first material  1206  and the second material  1208  are cross-sectioned to illustrate the relative location to the beam  1204 . In this winding, the entirety of the first material  1206  is wound around the beam  1204  prior to the second material  1208  being wound around the first material  1206 . Stated differently, SCF CO 2    1302  passes through substantially the wound thickness of the first material  1206  before passing through the second material  1208  as SCF CO 2 +dye  1304 . The SCF CO 2  is then expelled from the second material  1208  as SCF CO 2 +dye  1306 , which may then be recirculated through one or more additional or other materials (e.g., first material  1206 ). Therefore, a cycle is formed in which the SCF CO 2 +dye perfuse the materials within the pressure vessel until the temperature or pressure are changed such that the SCF changes state, at which time, the dyestuff will become integral with the material with which it was in contact at the time of the SCF state change, in an exemplary aspect. 
     In this illustrated example, the last turn of the first material  1206  exposes a surface that is in direct contact with a surface of the first turn of the second material  1208 . Stated differently, the depicted series rolling of winding  1300  allows for a limited, but available, direct contact between the first material  1206  and the second material  1208 . This direct contact can be distinguished over alternative aspects in which a dye carrier or the dyestuff is physically separate from the material to be dyed. As such, the direct contact between the materials to be dyed and having the dyestuff may reduce dyeing time and reduce potential cleaning and maintenance times, in an exemplary aspect. 
       FIG. 8  depicts a second exemplary winding  1401  of multiple materials on a beam  1204  for SCF dyeing, in accordance with aspects hereof. The winding  1401  is comprised of the beam  1204 , the first material  1206 , and the second material  1208 . The first material  1206  and the second material  1208  are cross-sectioned to illustrate the relative location to the beam  1204 . In this winding, the first material  1206  is contemporaneously wound around the beam  1204  with the second material  1208 . Stated differently, SCF CO 2    1407  passes through alternating layers of the first material  1206  and the second material  1208  allowing for multiple direct contact between the materials as multiple turns of each material are contact the other material as they wind about the beam  1204 . In this example, the SCF CO 2    1407  transfers dye between the materials achieving transfer of dyestuff in potentially a shorter cycle because of the consistent distance from dyestuff source and target (e.g., 1 material thickness distance). SCF CO 2 +dye  1405  may expel from the materials (e.g., second material  1208 ) for recirculation through the materials and further propagation of the equilibrium of dyestuff. 
     While only two materials are depicted in  FIGS. 7 and 8 , it is contemplated that any number of materials may be wound relative to one another in any manner, in additional exemplary aspects. Further, it is contemplated that a combination of physical arrangement may be implemented with respect to the materials. For example, it is contemplated that two or more sacrificial materials may be arranged as depicted in  FIG. 7 or 8  while a target material is not in contact with the sacrificial material. Stated differently, it is contemplated that one or more materials may be in physical contact with one another while one or more materials may be physically separate from one another in a common pressure vessel for a common SCF dyeing process, in accordance with aspects hereof. 
       FIG. 13  depicts a flow chart  508  of an exemplary method of equilibrium dyeing a material, in accordance with aspects hereof. At a block  510 , a first material and a second material are positioned in a pressure vessel. As previously discussed, the materials may be wound about a beam prior to being positioned in the vessel. The materials may be positioned by moving the materials as rolled together into the pressure vessel. Also, it is contemplated that the material may be wound about a beam in a variety of manners (e.g., in series, in parallel). Further, it is contemplated that the materials may be maintained on different holding devices and positioned in a common pressure vessel. 
     At a block  512 , the pressure vessel may be pressurized. In an exemplary aspect, the materials are loaded into the pressure vessel and then the pressure vessel is sealed and pressurized. In order to maintain inserted CO 2  in the SCF phase, the pressure, in an exemplary aspect, is raised above the critical point (e.g., 73.87 bar). 
     Regardless of how the pressure vessel is brought to pressure, at a block  514 , CO 2  is introduced (or recirculated) into the pressure vessel. This CO 2  may be introduced by transitioning CO 2  maintained in the pressure vessel from a first state (i.e., liquid, gas, or solid) into a SCF state. As know, the state change may be accomplished by achieving a pressure and/or temperature sufficient for a SCF phase change. It is contemplated that one or more heating elements are engaged to raise the internal temperature of the pressure vessel to a sufficient temperature (e.g., 304 K, 30.85 C). One or more heating elements may also (or alternatively) heat the CO 2  as (or before) it is introduced into the pressure vessel, in an exemplary aspect. The introduction of CO 2  may occur during pressurization, prior to pressurization, and/or subsequent to pressurization. 
     At a block  516 , the SCF CO 2  is passed through the first material and the second material. In an exemplary aspect, the SCF CO 2  is pumped into a beam about which one or more of the materials are wound. The SCF CO 2  is expelled from the beam into the materials. While the SCF CO 2  passes through the materials, which may have different dye profiles, dyestuffs is transferred between the materials and perfuse the material(s). In an exemplary aspect, the dyestuff is dissolved in the SCF CO 2  such that the SCF CO 2  serves as a solvent and carrier for the dyestuff. Further, because of the temperature and pressure of the SCF CO 2 , the materials may alter (e.g., expand, open, swell), temporarily, to be more receptive to dyeing by the dyestuff. 
     It is contemplated that the passing of SCF CO 2  is a cycle in which the SCF CO 2  is passed through the materials multiple times, such as in a closed system with a circulation pump, in an exemplary aspect. It is this circulation that may help achieve the dyeing. In an aspect, the SCF is circulated through the materials for a period of time (e.g., 60 minutes, 90 minutes, 120 minutes, 180, minutes, 240 minutes) and then the SCF CO 2  is allowed to change state (e.g., to a liquid CO 2 ) by dropping temperature and/or pressure. After changing state of the CO 2  from SCF state, the dyestuff is no longer soluble in the non-SCF CO 2 , in an exemplary aspect. For example, dyestuff may be soluble in SCF CO 2 , but when the CO 2  transitions to liquid or gas CO 2 , the dyestuff may no longer be soluble in the liquid or gas CO 2 . It is further contemplated that the CO 2  is circulated internally (e.g., passed through a material holder or a beam) and/or the CO 2  is circulated as a recapture process to reduce lost CO 2  during phase changes (e.g., depressurization). 
     At a block  518 , the first material and the second material are extracted from the pressure vessel. In an exemplary aspect, the pressure within the pressure vessel is reduced to near atmospheric pressure and the CO 2  is recaptured from the pressure vessel for potential reuse in subsequent dyeing operations. In an example, a beam having the materials wound thereon may be moved out of the vessel after a desired dye profile is achieved for one or more of the materials. 
     While specific steps are discussed and depicted in  FIG. 13 , it is contemplated that one or more additional or alternative steps may be introduced to achieve aspects hereof. Further, it is contemplated that one or more of the listed steps may be omitted altogether to achieve aspects provided herein. 
       FIG. 14  depicts a flow chart  1400  of a method for dyeing materials with SCF CO 2 , in accordance with aspects hereof. The method has at least two different starting positions. A first approach, as indicated at block  1402 , is a winding of a first material around a beam. At a block  1404 , a second material is wound around the first material from the block  1402 . The blocks  1402  and  1404  may result in a winding similar to that which is generally depicted in  FIG. 7 or 8 . 
     In the alternative, the second starting position of  FIG. 14  is represented at a block  1403  with the winding of a first material about a holding device, such as a beam, and the winding of a second material about a holding device, which may be the same or different holding device on to which the first material was placed. In the step depicted at the block  1403 , the first material and the second material are not in physical contact with each other. The step provided by the block  1403  may result in a material positioning that is generally depicted in  FIG. 6 . 
     In both the first and the second starting positions, the multiple materials are wound, in one manner or another, about one or more holding devices for positioning in a common pressure vessel, as depicted at a block  1406 . 
     At a block  1408  the pressure vessel is pressurized to at least 73.87 bar. This pressurization may be accomplished by injection of atmospheric air and/or CO 2  until the internal pressure of the pressure vessel reaches the desired pressure, such as at least the critical point pressure of CO 2 . For example, CO 2  is inserted into the pressure vessel with a pump until the appropriate pressure is achieved within the pressure vessel. 
     At a block  1410 , SCF CO 2  is passed through the first material and the second material to cause a change in a dye profile for at least one of the first material or the second material. The dye transfer may be continued until the dyestuffs perfuse the materials(s) sufficiently to achieve a desired dye profile. An internal recirculating pump is contemplated as being effective to cycle the SCF CO 2  through the beam and wound materials multiple times to achieve the equilibrium dyeing, in an exemplary aspect. This internal recirculating pump may be adjusted to achieve a desired flow rate of the SCF CO 2 . The flow rate provided by the internal recirculating pump may be affected by the amount of material, the density of material, the permeability of the material, and the like. 
     At a block  1412 , the first material and the second material are extracted from the pressure vessel such that color profiles (e.g., dye profile) of the materials are different relative to the color profiles of the materials as existed at blocks  1402 ,  1403 , or  1404 . Stated differently, upon completion of the SCF CO 2  passing through the materials, the dye profiles of at least one of the materials changes to reflect that it has been dyed by SCF CO 2 . 
     While specific reference in  FIG. 14  is made to one or more steps, it is contemplated that one or more additional or alternative steps may be implemented while achieving aspects provided herein. As such, blocks may be added or omitted while still staying within the scope hereof. 
     Process 
     The process of using SCF CO 2  in a material dyeing or finishing application relies on manipulation of multiple variables. The variables include time, pressure, temperature, quantity of CO 2 , and flow rate of the CO 2 , rate of change for one or more variables over time (e.g., change in pressure per minute, change in temperature per minute), and exchange of CO 2 . Further, there are multiple cycles in the process in which one or more of the variables may be manipulated to achieve a different result. Three of those cycles include a pressurizing cycle, a perfusing cycle (also referred to as a “dyeing cycle”), and a depressurizing cycle. In an exemplary scenario, CO 2  is introduced into a sealed pressure vessel with the temperature and the pressure increasing such that the CO 2  is elevated to at least the critical point of 304 K and 73.87 bar. In this traditional process, the second cycle of perfusing (e.g., dyeing) the material-to-be-finished occurs. A flow rate of a recirculating pump may be set and maintained and a time is established for the dyeing cycle. Finally, at the depressurization cycle in a traditional process, the flow rate may be stopped, the application of thermal energy ceases, and the pressure is reduced, all substantially simultaneously or at varied intervals to transition the CO 2  from SCF to gas. For example, the temperature may be maintained or at least maintained above a threshold level during the depressurization cycle while pressure is reduced. The temperature is maintained until, in an example, the density of the CO 2  changes to a point that no longer supports maintaining the dyestuff in solution with the CO 2 . At which point, the temperature may also decrease. This delayed temperature decrease may increase collection of dyestuff by the target material that is more receptive to dyestuff perfusion at elevated temperatures. Therefore, maintaining the elevated temperature during the transition of the CO 2  density may reduce deposition of dyestuff onto the pressure vessel components as the target material remains a more attractive target for the dyestuff coming out of solution from the CO 2 . 
     Improvements over a traditional process are able to be realized by adjusting the different variable. In particular, adjusting the sequence and timing of the variable changes during a cycle provides better results. For example, a traditional process may cause the material finish (e.g., dyestuff) to coat the inner surfaces of the pressure vessel. The coating of the pressure vessel is inefficient and undesired as it represents material finish that was not perfused through the intended material and requires subsequent cleaning to ensure the material finish is not perfused into a subsequent material for which it is not intended. Stopping the flow rate at the initiation of the third cycle causes the CO 2  and the material finishes dissolved therein to become stagnate within the pressure vessel. As CO 2  transitions from SCF to gas, the material finish in this stagnant environment may not find a suitable host to attach as the material finish comes out of solution with the CO 2  at the phase change. Therefore, the pressure vessel itself may become the target of the surface finish as opposed to the target material. Manipulation of the variables may allow for the material finish to favor adhering/bonding/coating the intended target material as opposed to the pressure vessel itself. 
     In the third cycle (e.g., depressurization cycle), it is contemplated that the flow rate is maintained or at least not ceased until the CO 2  changes from the SCF to gas state. For example, if the pressure within the pressure vessel is operating at 250 bar during the perfusing cycle, the CO 2  may stay in SCF state in the third cycle until the pressure is reduced below 73.87 bar. As a result, when the second cycle is completed, instead of stopping the flow of CO 2  or significantly reducing the flow rate of CO 2  within the pressure vessel, the flow rate is maintained through at least a portion of the third cycle. In an additional concept, the flow rate of the CO 2  is maintained until the pressure reduces below 73.87 bar. Additionally or alternatively, it is contemplated that the flow rate is maintained above a threshold until the CO 2  passes a defined density at which the dyestuff comes out of solution with the CO 2 . 
     At least two different scenarios for the third cycle are contemplated. The first scenario is a sequence where the third cycle of the process initiates at the reduction in temperature of the CO 2 . For example, the second cycle may be operating at 320 K, in an exemplary aspect, at the completion of the second cycle, the temperature is allowed to decline from the operating temperature of 320 K. While a traditionally process may also stop the flow of CO 2  within the pressure as the temperature begins to decline, it is contemplated that instead the flow rate is maintained, at some level, until at least the temperature falls below the critical temperature of CO 2 , 304 K/30.85 C. In this example, the CO 2  may remain in the SCF until the temperature falls below 304 K/30.85; therefore, the flow rate is maintained to circulate the CO 2  and deposit material finishes therein around and/or through the target material. In this first scenario, the pressure may be maintained at the operating pressure (or above 73.87 bar) until the CO 2  changes from SCF to another state (e.g., liquid if above 73.87 bar). Alternatively, the pressure may also be allowed to drop at the commencement of the third cycle, but the flow is maintained until at least the CO 2  changes to a different state and/or a defined CO 2  density is achieved. 
     The second scenario, while similar to the first, relies on the third cycle being initiated by a decline in pressure. For example, if the operating pressure within the pressure vessel to perfuse the material is 250 bar, the third cycle is initiated when the pressure drops. While a traditional process may cease the flow rate of the CO 2  at this point, it is contemplated that instead the flow rate is maintained or not ceased simultaneously. Instead, at the third cycle, the CO 2  is subject to flow until the pressure drops below at least 73.87 bar to ensure circulation of the CO 2  having dissolved material finishes contained therein the entirety of time the CO 2  is at a SCF state. The temperature may also be dropped simultaneously with the pressure decline or it may be maintained until a certain pressure or CO 2  density is achieved. It is contemplated that some dyestuff (e.g., surface finishes) may come out of solution with the CO 2  prior to the CO 2  transitioning from the SCF state. Therefore, the transition pressure at which other variable are adjusted may instead be based on the density of the CO 2  (e.g., 500 Kg/m 3 ). 
     In an exemplary aspect, the third cycle initiates with the pressure dropping and the temperature dropping toward the CO 2  critical point, but the flow rate of the CO 2  is maintained, at least in part, until the CO 2  has transitioned from the SCF state. While specific temperatures and pressures are listed, it is contemplated that any temperature or pressure may be used. Further, instead of relying on the CO 2  achieving a particular temperature or pressure, a time may be used for when to reduce or cease the CO 2  flow rate, in an exemplary aspect. 
     Manipulation of the variable is not limited to the third cycle. It is contemplated that a higher equilibrium saturation of surface finish may be achieved by adjusting the variables in the first and second cycles. For example, the flow rate may begin before the CO 2  transitions from a first state (e.g., gas or liquid) to a SCF state. It is contemplated that as CO 2  transitions into a SCF state, the material finish that is to-be-dissolved in the SCF is exposed to a non-stagnate pool of CO 2  allowing an for an equilibrium of solution to occur sooner, in an exemplary aspect. Similarly, it is contemplated that the thermal energy is applied to the pressure vessel internal volume before the introduction of CO 2  and/or before the pressurization of the CO 2  begins. As the transfer of thermal energy may slow the process because of thermal mass of the pressure vessel, it is contemplated that the addition of the thermal energy occurs, in an exemplary aspect prior to the application of pressure. As such, it is contemplated that manipulation of variables during the pressurization cycle may allow the dyestuff to dissolve in the CO 2  at a faster rate. For example, the rate of pressure increase relative to temperature increase during the pressurization cycle may be manipulated through temperature hold periods, which can enhance the dyestuff dissolving in the CO 2 , for example. 
     Additionally, the manipulation of variables may further affect the resulting dyeing process of the target material. For example, at certain cycles (e.g., dyeing cycle) an increase of flow rate may increase color levelness (e.g., uniformity of finish deposition on the target material) and at certain cycles (e.g., depressurization cycle) a decrease in flow rate can improve color fastness (e.g., bond strength of material finish with the target material). Further yet, the flow rate in certain cycles (e.g., pressurization cycle) may be varied to enhance solubility results of the dyestuff in the CO 2 . Further yet, the permeability of the target material may affect variables, such as flow rate. For example, a higher permeability material (e.g., knit) may use a lower flow rate to achieve a sufficient degree of color levelness while also achieving a sufficient degree of color fastness relative to a lower permeability material (e.g., tightly woven). As such, the process variable may adjust based on the material characteristics as well as degree of dyeing results tolerated. 
     In further support of the general processes provided above, specific examples are provided hereinafter. 
       FIG. 15  depicts a flow chart  508  representing an exemplary method of applying a finish material to a target material, in accordance with aspects hereof. At a block  510 , a target material, such as polyester, is positioned in a pressure vessel. The target material may be a rolled material and/or a spooled material in an exemplary aspect. The target material may have a weight between 100 and 200 Kg in an exemplary aspect. However, lesser or greater weights are contemplated. 
     At a block  512 , CO 2  is introduced into the pressure vessel. As discussed herein, the CO 2  may be introduced in any state, such as a gaseous state to the enclosed pressure vessel. At a block  514 , an internal temperature of the pressure vessel is increased to an operating temperature. For example, it is contemplated that the pressure vessel may have a pre-heated temperature, such as 80-90 Celsius in an exemplary aspect, from which the pressure vessel is further heated. The operating temperature may be within a range of 100-125 Celsius in an aspect. The operating temperature may be around 110 Celsius in an aspect. The operating temperature may depend on the target material composition (e.g., synthetic materials). As discussed herein, a temperature within a range of 100-125 Celsius allows for a polyester target material to open up pores for physically capturing a finishing material without melting the polyester, in an exemplary aspect. In an exemplary aspect, the temperature is at least a glass transition temperature of the target material. This temperature (e.g., 60-70 Celsius for polyester) allows hydrophobic polymers of a hydrophobic material to be opened to diffusion of dispersed finish materials. Further, the operating temperature should be sufficient for the CO 2  to achieve (or nearly achieve) a SCF state. 
     At a block  516 , a pump mechanism is activated to increase a flow rate above a zero flow rate for internal circulation of CO 2 . For example, prior to the CO 2  achieving SCF state, the pump is activated to circulate the CO 2  as it achieves a SCF state and begins dissolving a finishing material contained within the pressure vessel. 
     At a block  518 , a pressure of the pressure vessel internal cavity is increased to an operating pressure. The operating pressure is sufficient to achieve a SCF state for the CO 2  when at the operating temperature. In an exemplary aspect, the operating pressure is below 300 bar. In an exemplary aspect, the operating pressure is in a range of 225-275 bar. In an exemplary aspect, the operating pressure is 250 bar. 
     At a block  1512 , the target material is perfused with a finishing material. The finishing material is transported to the target material as the finishing material is dissolved in the SCF CO 2  and circulated by the pump controlling the flow rate of the CO 2 . The perfusing of the target material allows for the infiltration and maintaining of the finishing material by the target material. The perfusing of the target material may continue for a predetermined time, such as 30, 45, 60, 75, 90, 120, 150, 180 minutes, in an exemplary aspect. 
     At a block  1514 , the pressure is reduced from the operating pressure to a transition pressure while maintaining the temperature above a threshold temperature and also while maintaining the flow rate above a threshold rate. The transition pressure may be any pressure from atmospheric pressure up to the operating pressure. In an aspect, the transition pressure is in a range of 225-100 bar. In an aspect the transition pressure is 200 bar, 150 bar, or 100 bar. The threshold temperature may be determined based on the target material. For example, if the target material the threshold temperature may be 100 Celsius. The threshold flow rate is a non-zero rate. Stated differently, the CO 2  is circulated as the pressure reduces from the operating pressure to the threshold pressure. As discussed herein, efficiencies are achieved by maintaining the temperature and/or the flow rates above threshold levels while the pressure is decreasing from the operating pressure. For example, as the dissolved material finish in the CO 2  begins to precipitate from the CO 2  as the density of the CO 2  transitions from the operating values, the circulation and or maintained temperature allow for a great uptake of the material finish by the target material than if the flow rate and/or the temperature are decreased below the threshold levels prior to the precipitation phase, in an exemplary aspect. 
       FIGS. 18-22  depict general trends between pressure, temperature, and flow rate of CO 2  during cycles of a SCF CO 2  material finishing process, in accordance with aspects hereof.  FIGS. 18-22  are comprised of three charted variables, temperature  1802 , pressure  1804 , and flow rate  1806 . Further, along the X axis, four cycles are delineated, a pressurization cycle  1808 , a dyeing/treatment cycle  1810 , a depressurization cycle  1812 , and a completion cycle  1814 . As provided herein, it is contemplated that the temperature, pressure, and flow rate may be varied at the initiation, completion, and/or during any of the delineated cycles. Further, it is contemplated that the variables may be adjusted in reaction to another variable achieving a threshold, as will be discuss hereinafter in more detail.  FIGS. 18-22  are provided for illustrative purposes and is not intended to be limiting in nature, but instead for exemplary purposes. 
     At the pressurization cycle  1808  CO 2  is filled into the pressure vessel. The pressure vessel may be preheated to a starting temperature, such as 50-90 Celsius in an exemplary aspect. However, it is contemplated that the vessel may not be preheated or it may be heated to a different starting temperature in exemplary aspects. The pressure within the vessel may start at atmospheric pressure in an exemplary aspect. The pressure in the pressurization cycle  1808  may be increased to a threshold pressure, such as 250 bar. However any pressure threshold above the critical point pressurization of CO 2  is contemplated. As will be discussed hereinafter, the pressurization threshold may be less than 310 bar to achieve process efficiency in time to pressurization and energy required to achieve such pressurization. Upon achieving a threshold pressure, the pressurization cycle  1808  may transition to the dyeing/treatment cycle  1810 , in an exemplary aspect. It is further contemplated that the transition from pressurization cycle  1808  to dyeing/treatment cycle  1810  may occur after another variable, including a preset time, is achieved. 
     Also depicted in  FIG. 18  at the pressurization cycle  1808  is the flow rate  1806  is achieving a first rate. In an exemplary aspect, the first rate of the flow rate is a non-zero value such that a pump (or other mechanism) is operating to circulate the CO 2  when the CO 2  is in a state capable of being circulated. The flow rate  1806  at a non-zero value in the pressurization cycle  1808  is effective, in an exemplary aspect, to aid in the dissolution of finishing material (e.g., dyestuff) while limiting a caking of the finishing material that may occur with a stagnate CO 2  lacking a flow rate as the CO 2  transition from a gas state to a SCF state in the presence of the material finish. The flow rate  1806  is contemplated as increasing at or leading up to the dyeing/treatment cycle  1810 ; however, it is also contemplated that a similar or greater flow rate may be implemented in alternative aspects during the pressurization cycle  1808  relative to the dyeing/treatment cycle  1810 . Further, it is also contemplated that the flow rate may be increased during the time of the pressurization cycle  1808 . For example, prior to the CO 2  achieving a SCF state, the flow rate may be initiated at a first rate and as the CO 2  enters and passes into SCF state, the flow rate may be increased. The increase in the flow rate of this example may increase to a flow rate intended for the dyeing/treatment cycle  1810 , in an exemplary aspect. 
     The slope of pressurization, temperature, and/or flow rate changes during one or more cycles is also variable. For example, it is contemplated that temperature is increased at a rate to achieve maximum time at the desired temperature for the dyeing/treatment cycle  1810  to allow the thermal mass of the material to be treated to equalize to benefit the perfusing and acceptance of the finishing material. For example, if the target material is polyester or other long-chain polymer, achieving a temperature above 100 Celsius may result in the pores of the polyester opening sufficient for the material finish to be perfused and maintained by the polyester. If an internal portion of the polyester material has yet to reach the 100 Celsius temperature as dissolved finishing material is being perfused through the polyester material, the adhesion of the finishing material may be hindered at portions of the polyester material, in an exemplary aspect. Similarly, it is contemplated that various rates of pressurization may be established. For example, as will be discussed in the depressurization cycle  1812 , a 5 bar per minute rate may be used to achieve a desired precipitation of the finishing material from the CO 2 , in an exemplary aspect. The pressurization rate may also be manipulated to achieve a specified pressurization cycle  1808  duration. 
     The dyeing/treatment cycle  1810  may equate to the second cycle in the above description of the CO 2  processing methodology. The duration of the dyeing/treatment cycle  1810  may be established based on a number of potential variables. For example, the duration may be established based on the type of target material, the characteristics of the material (e.g., permeability, density), the material finish to be applied (e.g., coloration, saturation of coloration, chemistry of finishing material, type of finishing material), flow rate of the CO 2 , the temperature, the pressure, and the like. 
     As depicted in  FIG. 18  for the dyeing/treatment cycle  1810 , the pressure  1804 , temperature  1802 , and the flow rate  1806  are maintained constant in this exemplary aspect. However, it is contemplated that the pressure, temperature, and/or flow rate may be adjusted in the dyeing/treatment cycle  1810 . For example, to achieve a varied CO 2  density having a different solubility of the finishing material (to be discussed hereinafter), the pressure may be adjusted to dissolve different chemistries at different points within the dyeing/treatment cycle  1810  and/or to cause the precipitation of various finishing material chemistries in specific sequences during the dyeing/treatment cycle  1810 , in an exemplary aspect. The duration of the dyeing/treatment cycle  1810  may be controlled by a number of variables, such as a preset time (e.g., 30 minutes, 45 minutes, 60 minutes, 90 minutes, 120 minutes, 150 minutes, 180 minutes), in an exemplary aspect. 
       FIG. 18  depicts a transition from the dyeing/treatment cycle  1810  to the depressurization cycle  1812  having a decrease in the pressure  1804 . The depressurization cycle  1812  may resemble the third cycle provided hereinabove. The change in pressure  1804  may be at a predetermined rate (e.g., slope). That rate may range from 1-10 bar per minute in exemplary aspects. In another exemplary aspect the pressure is decreased at about 5 bar per minute. Further, the pressure change may be based, in part, on the characteristics of the CO 2  as it transitions between different states or densities. 
     In the example depicted in  FIG. 18 , the temperature  1802  and the flow rate  1806  are maintained at the beginning of the depressurization cycle  1812  even while the pressure  1804  is reduced. However, it is contemplated that either of the temperature or the flow rate may be reduced and/or increased at the initiation of the depressurization cycle  1812 . However, in an exemplary aspect, having the flow rate at a non-zero rate allows for the continued circulation of CO 2  as the finishing material precipitates out of the CO 2 . This continued circulation during the precipitation phase of the finishing material provides several advantages in exemplary aspects. For example, the affinity of the finishing material in the precipitation phase out of the CO 2  may favor the target material more than the CO 2  allowing for a higher concentration of the finishing material to be maintained by the target material. The pressure vessel and components therein (e.g., carrier beam/holding member) are not desired to maintain and/or attract the finishing material at the conclusion of the process. Therefore, as opposed to stopping the flow rate prior to the finishing material precipitating out of the CO 2 , which can cause a stagnate environment in which the precipitated finishing material is maintained to a surface (e.g., pressure vessel wall) as opposed to the target material, the continued flow of CO 2  provides the finishing material to be perfused through the target material in the precipitation phase of the depressurization cycle  1812 . 
     In an exemplary aspect, once the pressure achieves a defined pressure (e.g., 200 bar) that also causes the finishing material to fully precipitate out of the CO 2 , in an exemplary aspect, the temperature may then be reduced, as depicted in the cycle  1814 . Further, it is contemplated that the flow rate  1806  may be changed at the initiation of the cycle  1814 . Additionally, it is contemplated that the flow rate  1806  may be changed upon the pressure/temperature/density achieving a predefined level, in an exemplary aspect. 
     The depressurization cycle  1812  provides other combination of variables to achieve different results. For example, it is contemplated that the pressure if reduced to a predefined threshold for recapture of the CO 2  and then the pressure is reduced to atmosphere with a loss of CO 2  to the environment. This rapid depressurization may occur after the finishing material has precipitated out of the CO 2  and the CO 2  has transitioned to a gaseous or liquid state. 
       FIG. 19  illustrates a decrease of the internal flow rate  706  during the depressurization cycle  712  from the flow rate during the dyeing/treatment cycle  1810 , in accordance with aspects hereof. This reduction of flow rate during the depressurization cycle  712  may be effective to increase affinity of the dyestuff with the target material for some dyestuff and/or target materials. 
       FIG. 20  illustrates a stepped  2002  temperature during the pressurization cycle  1808 , in accordance with aspects hereof. The step  902  may maintain the CO 2  at a defined temperature for a defined time. For example, the temperature may be maintained at 100 Celsius for 5-15 minutes. In an exemplary aspect, the step  902  is 5 minutes, 10 minutes, or 15 minutes. The time and temperature associated with the step  902  may depend on the dyestuff and the density of CO 2  at which the dyestuff is soluble. For example, the step  902  may occur at a point relative to pressure increase to enhance the solubility of the dyestuff in the CO 2 . 
       FIG. 21  illustrates a multiple stepped  2102 ,  2104  temperature during the pressurization cycle  1808 , in accordance with aspects hereof. The steps  2102 ,  2104  may maintain the CO 2  at defined temperatures (e.g., 100, 110 Celsius) for defined time (e.g., 5, minutes, 5 minutes). In an exemplary aspect, the step  2102  is 5 minutes, 10 minutes, or 15 minutes. In an exemplary aspect, the step  2104  is 5 minutes, 10 minutes, or 15 minutes. The defined temperature at the step  2102  is 100 Celsius, in an exemplary aspect. The defined temperature at the step  2104  is 110 Celsius, in an exemplary aspect. The time and temperature associated with the steps  2102 ,  2104  may depend on the dyestuff and the density of CO 2  at which the dyestuff is soluble. For example, the steps  2102 ,  2104  may occur at points relative to pressure increase to enhance the solubility of a first dyestuff and a second dyestuff respectively in the CO 2 . 
       FIG. 22  illustrates a manipulation  2202  of the internal flow rate  706  relative to the steps  2102 , 2104  of  FIG. 21 , in accordance with aspects hereof. In an exemplary aspect, the flow rate is reduced, stopped, or maintained in relation to one or more variables, such as the stepping of temperature. This adjustment of the flow rate may enhance the solubility of exemplary dyestuff in the CO 2 . 
       FIGS. 18-22  are illustrative in nature and not limiting. Each depiction of a variable (e.g., temperature  1802 , pressure  1804 , and flow rate  1806 ) is merely relative and not provided to a scale. Further, it is contemplated that values may be achieved for the variables prior to or after the points depicted, in exemplary aspects. 
     The following is a listing of exemplary variable settings for the pressurization, dyeing, and depressurization cycles that may be implemented to achieve aspects provided herein. Each row represents a variation in the variables to achieve a CO 2  dyeing process for a particular target material and/or dyestuff. However, the values provided are not limiting. 
     Exemplary Condition 1—See  FIG. 18  for example.
         Pressurization: Start Temp: 80-90 Celsius, Pressure: 188-250 Bar, Flow rate: 90-130 m 3 /hr.   Dyeing: Temp: 120 Celsius, Pressure: 250 Bar, Flow rate: 230-240 m 3 /hr.   Depressurization: Starting Temp: 120 Celsius, Ending Pressure: 150 Bar, Flow rate: 230-240 m 3 /hr.       

     Exemplary Condition 2—See  FIG. 18  for example.
         Pressurization: Starting Temp: 80-90 Celsius, Pressure: 188-250 Bar, Flow rate: 90-130 m 3 /hr.   Dyeing: Temp: 120 Celsius, Pressure: 250 Bar, Flow rate: 230-240 m 3 /hr.   Depressurization: Starting Temp: 120 Celsius, Ending Pressure: 100 Bar, Flow rate: 230-240 m 3 /hr.       

     Exemplary Condition 3—See  FIG. 19  for example.
         Pressurization: Starting Temp: 80-90 Celsius, Pressure: 188-250 Bar, Flow rate: 90-130 m 3 /hr.   Dyeing: Temp: 120 Celsius, Pressure: 250 Bar, Flow rate: 230-240 m 3 /hr.   Depressurization: Starting Temp: 120 Celsius, Ending Pressure: 150 Bar, Flow rate: 90-130 m 3 /hr.       

     Exemplary Condition 4—See  FIG. 19  for example.
         Pressurization: Starting Temp: 80-90 Celsius, Pressure: 188-250 Bar, Flow rate: 90-130 m 3 /hr.   Dyeing: Temp: 120 Celsius, Pressure: 250 Bar, Flow rate: 230-240 m 3 /hr.   Depressurization: Starting Temp: 120 Celsius, Ending Pressure: 100 Bar, Flow rate: 90-130 m 3 /hr.       

     Exemplary Condition 5—See  FIG. 19  for example.
         Pressurization: Starting Temp: 80-90 Celsius, Pressure: 188-250 Bar, Flow rate: 90-130 m 3 /hr.   Dyeing: Temp: 120 Celsius, Pressure: 250 Bar, Flow rate: 175-200 m 3 /hr.   Depressurization: Starting Temp: 120 Celsius, Ending Pressure: 150 Bar, Flow rate: 90-130 m 3 /hr.       

     Exemplary Condition 6—See  FIG. 19  for example.
         Pressurization: Starting Temp: 80-90 Celsius, Pressure: 188-250 Bar, Flow rate: 90-130 m 3 /hr.   Dyeing: Temp: 120 Celsius, Pressure: 250 Bar, Flow rate: 175-200 m 3 /hr.   Depressurization: Starting Temp: 120 Celsius, Ending Pressure: 100 Bar, Flow rate: 90-130 m 3 /hr.       

     Exemplary Condition 7—See  FIG. 19  for example.
         Pressurization: Starting Temp: 80-90 Celsius, Pressure: 188-250 Bar, Flow rate: 90-130 m 3 /hr.   Dyeing: Temp: 115 Celsius, Pressure: 250 Bar, Flow rate: 230-240 m 3 /hr.   Depressurization: Starting Temp: 115 Celsius, Ending Pressure: 150 Bar, Flow rate: 90-130 m 3 /hr.       

     Exemplary Condition 8—See  FIG. 19  for example.
         Pressurization: Starting Temp: 80-90 Celsius, Pressure: 188-250 Bar, Flow rate: 90-130 m 3 /hr.   Dyeing: Temp: 115 Celsius, Pressure: 250 Bar, Flow rate: 230-240 m 3 /hr.   Depressurization: Starting Temp: 115 Celsius, Pressure: 100 Bar, Flow rate: 90-130 m 3 /hr.       

     Exemplary Condition 9—See  FIG. 19  for example.
         Pressurization: Starting Temp: 80-90 Celsius, Pressure: 188-250 Bar, Flow rate: 90-130 m 3 /hr.   Dyeing: Temp: 115 Celsius, Pressure: 250 Bar, Flow rate: 175-200 m 3 /hr.   Depressurization: Starting Temp: 115 Celsius, Ending Pressure: 150 Bar, Flow rate: 90-130 m 3 /hr.       

     Exemplary Condition 10—See  FIG. 19  for example.
         Pressurization: Starting Temp: 80-90 Celsius, Pressure: 188-250 Bar, Flow rate: 90-130 m 3 /hr.   Dyeing: Temp: 115 Celsius, Pressure: 250 Bar, Flow rate: 175-200 m 3 /hr.   Depressurization: Starting Temp: 115 Celsius, Ending Pressure: 100 Bar, Flow rate: 90-130 m 3 /hr.       

     Exemplary Condition 11—See  FIG. 19  for example.
         p Pressurization: Starting Temp: 80-90 Celsius, Pressure: 188-250 Bar, Flow rate: 90-130 m 3 /hr.   Dyeing: Temp: 115 Celsius, Pressure: 250 Bar, Flow rate: 175-240 m 3 /hr.   Depressurization: Starting Temp: 115 Celsius, Ending Pressure: 100-150 Bar, Flow rate: 90-130 m 3 /hr.       

     Exemplary Condition 12—See  FIG. 19  for example. 
     Pressurization: Starting Temp: 80-90 Celsius, Pressure: 188-250 Bar, Flow rate: 90-130 m 3 /hr.
         Dyeing: Temp: 110 Celsius, Pressure: 250 Bar, Flow rate: 175-240 m 3 /hr.   Depressurization: Starting Temp: 110 Celsius, Ending Pressure: 100-150 Bar, Flow rate: 90-130 m 3 /hr.       

     Exemplary Condition 13—See  FIG. 19  for example.
         Pressurization: Starting Temp: 80-90 Celsius, Pressure: 188-250 Bar, Flow rate: 90-130 m 3 /hr.   Dyeing: Temp: 110-120 Celsius, Pressure: 250 Bar, Flow rate: 175-240 m 3 /hr.   Depressurization: Starting Temp: 110-120 Celsius, Ending Pressure: 100-150 Bar, Flow rate: 90-130 m 3 /hr.       

     Exemplary Condition 14—See  FIG. 20  for example.
         Pressurization: Start Temp: 80-90 Celsius, maintain 100 Celsius for 10 minutes, End Temp: 110-120 Celsius, Pressure: 188-250 Bar, Flow rate: 90-130 m 3 /hr, External Pump: Off during temperature maintain.   Dyeing: Temp: 110-120 Celsius, Pressure: 250 Bar, Flow rate: 175-240 m 3 /hr.   Depressurization: Starting Temp: 110-120 Celsius, Ending Pressure: 100-150 Bar, Flow rate: 90-130 m 3 /hr.       

     Exemplary Condition 15—See  FIG. 20  for example.
         Pressurization: Start Temp: 80-90 Celsius, maintain 100 Celsius for 5 minutes, maintain 110 Celsius for 5 minutes, End Temp: 110-120 Celsius, Pressure: 188-250 Bar, Flow rate: 90-130 m 3 /hr, External Pump: Off during temperature maintain.   Dyeing: Temp: 110-120 Celsius, Pressure: 250 Bar, Flow rate: 175-240 m 3 /hr.       

     Depressurization: Starting Temp: 110-120 Celsius, Ending Pressure: 100-150 Bar, Flow rate: 90-130 m 3 /hr. 
     Exemplary Condition 16—See  FIG. 21  for example.
         Pressurization: Start Temp: 80-90 Celsius, maintain 100 Celsius for 10 minutes, maintain 110 Celsius for 10 minutes, End Temp: 110-120 Celsius, Pressure: 188-250 Bar, Flow rate: 90-130 m 3 /hr, External Pump: Off from first temp maintain to second temp maintain.   Dyeing: Temp: 110-120 Celsius, Pressure: 250 Bar, Flow rate: 175-240 m 3 /hr. Depressurization: Starting Temp: 110-120 Celsius, Ending Pressure: 100-150 Bar, Flow rate: 90-130 m 3 /hr.       

     Exemplary Condition 17—See  FIG. 21  for example.
         Pressurization: Start Temp: 80-90 Celsius, maintain 100 Celsius for 5-10 minutes, maintain 110 Celsius for 5-10 minutes, End Temp: 110-120 Celsius, Pressure: 188-250 Bar, Flow rate: 90-130 m 3 /hr, External Pump: Off during temperature maintaining.   Dyeing: Temp: 110-120 Celsius, Pressure: 250 Bar, Flow rate: 175-240 m 3 /hr, Time: 90 minutes.   Depressurization: Starting Temp: 110-120 Celsius, Ending Pressure: 100-150 Bar, Flow rate: 90-130 m 3 /hr.       

     Exemplary Condition 18—See  FIG. 22  for example.
         Pressurization: Start Temp: 80-90 Celsius, maintain 100 Celsius for 5-10 minutes, maintain 110 Celsius for 5-10 minutes, End Temp: 110-120 Celsius, Pressure: 188-250 Bar, Flow rate: 90-130 m 3 /hr, External Pump: Off during temperature maintaining.   Dyeing: Temp: 110-120 Celsius, Pressure: 250 Bar, Flow rate: 175-240 m 3 /hr, Time: 60 minutes.   Depressurization: Starting Temp: 110-120 Celsius, Ending Pressure: 100-150 Bar, Flow rate: 90-130 m 3 /hr.       

     Exemplary Condition 19—See  FIG. 22  for example.
         Pressurization: Start Temp: 80-90 Celsius, maintain 100 Celsius for 5-10 minutes, maintain 110 Celsius for 5-10 minutes, End Temp: 110-120 Celsius, Pressure: 188-250 Bar, Flow rate: 90-130 m 3 /hr, External Pump: Off during temperature maintaining.   Dyeing: Temp: 110-120 Celsius, Pressure: 250 Bar, Flow rate: 175-240 m 3 /hr, Time: 60-120 minutes.   Depressurization: Starting Temp: 110-120 Celsius, Ending Pressure: 100-150 Bar, Flow rate: 90-240 m 3 /hr.       

     As can be appreciated, variations in the combinations of variables, the timing of the variables, and the thresholds for each variable may be adjusted to achieve a result. For example, as the characteristics of the target material change, as the quantity and type of dyestuff change, the variables may be manipulated. The above-provided exemplary conditions are representative, but not limiting. Instead, combinations of variables may be combined as needed. A table is reproduced in  FIG. 27  hereinafter providing exemplary conditions for various cycles of SCF dyeing, in accordance with aspects hereof. 
     Absorbent Material Finish Carrier Having a Different Polarity 
     As provided herein, a sacrificial material may be used as a transport vehicle to introduce the material finish (e.g., dyestuff) intended to be perfused through the target material. In an exemplary aspect, the material finish is soluble in CO 2  SCF allowing the SCF to dissolve the material finish to perfuse the material. SCF is non-polar; therefore, the chemistry of material finishes that are operable in a CO 2  SCF processing system are chemistries that dissolve in a non-polar solution. For example, dyestuff suitable for dyeing a polyester material may dissolve in CO 2  SCF, but not dissolve in water. Further, the dyestuff suitable for dyeing polyester may not have the appropriate chemistry to bond with a different material, such as an organic material like cotton. Therefore, it is contemplated that an organic material (e.g., cotton) is soaked in the material finish to be applied to a polyester material. The soaked organic material serves as the carrier material into the pressure vessel. When the CO 2  SCF process is performed, the material finish is dissolved by the CO 2  SCF and perfused through the polyester material. The organic material, which would require a different chemistry for material finish bonding, does not maintain the material finish and therefore the intended amounts of the material finish are available for the perfusing the target material. 
     In an example, a cotton material is used as a transport vehicle for dyestuff to dye a polyester material. In this example, 150 kg of polyester is desired to be dyed in a CO 2  SCF process. If 1% of total target weight represents the amount of dyestuff needed to achieve a desired coloration. Then 1.5 kg of dyestuff is needed to be perfused into the polyester to achieve the desired coloration. The 1.5 kg of dyestuff may be diluted in an aqueous solution with 8.5 kg of water. Therefore, the dyestuff in solution is 10 kg. Because the dyestuff has a chemistry suitable for dissolving in a non-polar CO 2  SCF, the dyestuff is merely suspended in the water as opposed to dissolved in the water, in this exemplary aspect. Cotton is highly absorbent. For example, cotton may be able to absorb up to 25 times its weight. Therefore, in order to absorb the 10 kg of dyestuff solution, a 0.4 kg portion of cotton (10/25=0.4) may serve as the carrier. However, it is contemplated that a larger portion of cotton may be used to achieve the transport of the dyestuff solution. In an exemplary aspect, a 30% absorption by weight of the cotton is contemplated. In the example above using 30% by weight absorption, the cotton is 33.3 kg to carry the 10 kg of dyestuff solution. It should be understood that the solution amount, dyestuff amount, and absorption amount may be adjusted to achieve the desired amount of material to be included in the pressure vessel for the dyeing process. 
     As applied to specific material finishing examples, it is contemplated that a material having different bonding chemistry needs than the target material (e.g., cotton to polyester) is submerged or otherwise soaked with a material finish solution. The soaked carrier material is then placed in the pressure vessel. The soaked carrier may be placed on a support structure or wrapped around the target material. The process of CO 2  SCF finishing may be initiated. The CO 2  SCF passes around and through the carrier material and dissolves the material finish for perfusing the target material with the material finish. At the completion of the material finish application, the CO 2  is transitioned from the SCF state to a gaseous or liquid state (in an exemplary aspect). The material finish, which does not have a bonding chemistry for the carrier material, is attracted to and maintained by the target material, in an exemplary aspect. Therefore, at the completion of the finish process, the material finish is applied to the target material and the carrier material is void of appreciable quantities of the material finish, in an exemplary aspect. 
     Carbon Dioxide Density Calculation 
     As provided herein, density of CO 2  affects a dissolution rate of dyestuff in SCF CO 2 . Changing of temperature and/or pressure affects the density of CO 2 , therefore, adjustments of the variables in the process affect the ability of the SCF CO 2  to have dyestuff dissolve therein. The density of CO 2  may be calculated using a number of techniques known to one of ordinary skill in the art. In an exemplary aspect, a method is provided by: R. Stryjek, J. H. Vera,  PRSV: An Improved Peng—Robinson Equation of State for Pure Compounds and Mixtures ; The Canadian Journal of Chemical Engineering, 64, April 1986. Other methods may also be implemented. 
     In an exemplary aspect, the temperature and pressure may be used to estimate a density of the CO 2  in terms of Kg/m 3 . For example, operating at a temperature of 110 Celsius (e.g., 383 K) and 250 bars results in the CO 2  having a density of 525 Kg/m 3 . As will be discussed, it is contemplated that a dyeing cycle of the process may operate at a relatively constant temperature, such as 100-120 Celsius (373-393 K) and a pressure of about 250 bars. With these temperature and pressure settings, the density of the SCF CO 2  may range from 566-488 Kg/m 3 . 
     SCF CO 2  acts as a solvent. The solubility of the SCF CO 2  varies based on the density of the SCF CO 2 , such that when temperature is maintained relatively constant the solubility of the SCF CO 2  increases with the density. Because density increases with pressure when temperature remains constant, the solubility of the CO 2  increases with pressure. 
     In addition to manipulation of pressure to affect solubility of CO 2 , it is contemplated that temperature may be changed while maintaining the pressure relatively constant in the dyeing cycle of the processes provided herein. However, the relative trend between density and temperature is more complex. At a constant density, solubility of CO 2  will increase with temperature. However, close to the critical point of the CO 2 , the density can drop sharply with a slight increase in temperature; therefore, close to the critical temperature, solubility often drops with increasing temperature, then rises again. 
     Further, it is contemplated that both the temperature and the pressure may be manipulated within the dyeing cycle of the process to affect the solubility by way of the CO 2  density to achieve a desired dissolution of a material finish, such as dyestuff. 
     In an exemplary aspect, the material placed within a pressure vessel to be treated by SCF CO 2  is a polyester-based material that may limit the manipulation of temperature and therefore changes in the density of CO 2  may be limited. For example, above 120 Celsius, polyester may approach or exceed a transition temperature that causes a change in the feel, look, and/or structure of the polyester. However, to achieve acceptable solubility characteristics of the CO 2 , the pressure may be manipulated to achieve a sufficient density of the CO 2 . Therefore, in exemplary aspects, the temperature is maintained below 120 Celsius to limit unintended effects on the material to be finished. 
     Because increasing pressure and/or temperature consumes resources, such as energy, that reduces the efficiency of the material finishing/dyeing process, aspects herein limit the pressure and or temperature to a range that is sufficient to achieve solubility of the material finish and also sufficient for interaction with the material being finished. In an exemplary aspect, sufficient temperature and pressure is 100-125 Celsius and a pressure less than 300 bars. In an exemplary aspect, the temperature is 100-115 Celsius and 225-275 bars, which allows for a sufficient CO 2  density to dissolve a multi-chemistry dyestuff and open the fibers of a polyester material for dyestuff permeation without negatively affecting the polyester of the to-be-finished material and without utilizing excessive energy resources trying to achieve a higher pressure. For example, a pressure of 310 bars and a temperature of 110 may also be executed to dye a polyester material; however, the 310 bar pressure consumes additional energy to achieve, which increases the cost and potential time of treating the material in a SCF CO 2  process. 
     Previously, a density above 600 Kg/m 3  was needed to achieve a sufficient solubility for a dyestuff to treat a material in the system. If the density of the CO 2  was below this value, the provided dyestuff would not dissolve in the CO 2  and therefore would not perfuse the material to-be-treated. For example, such as system may be disclosed in  Supercritical Fluid Technology In Textile Processing: An Overview ; Ind. Eng. Chem. Res. 2000, 39, 4514-41512. In the above system, a single dye chemistry is explored being dissolved at a CO 2  density exceeding 600 Kg/m 3  and utilization of the CO 2  in the range of 566-488 Kg/m 3  would not be sufficient to dissolve the explored dyestuff of that system. Therefore, to save energy, improve efficiency, and limit unintended effects on the material being finished, aspects herein contemplate limiting the density below 600 Kg/m 3 . 
     Further, it is contemplated that aspects hereof are configured for flexibility of finish material to be applied. For example, aspects contemplate a multi-chemistry dyestuff being applied to the target material by SCF CO 2 . Because there are multiple chemistries (e.g., multiple colors, multiple finishes, combinations of coloration and finishes, etc.), the various unique chemistries may have different CO 2  densities at which they dissolve. Therefore, the chemistries are selected, in an exemplary aspect, to dissolve at the CO 2  in the range of 566-488 Kg/m 3 , in an exemplary aspect. An exemplary aspect contemplates a multi-chemistry finish, such as a three (or more) color dyestuff combination. While the unique chemistries of the dyestuff dissolve in CO 2  at different CO 2  densities, each of the chemistries are soluble within the parameters of the system, such as a density of the CO 2  in the range of 566-488 Kg/m 3 . In an exemplary aspect the multiple chemistry finishes are an unrefined dyestuff that is soluble in CO 2  at a density in the range of 566-488 Kg/m 3 . 
     The resulting feel (also referred to as “hand”) of a material after finishing is an important criteria to consider when performing a finishing operation. In an exemplary aspect, it is contemplated that the material resulting from a SCF CO 2  finishing process should have a similar feel (or hand) to that of a material finished in a water-based process. Therefore, it is contemplated that the variables achieving different CO 2  densities may further be constrained based on their effect on the hand of the finished material. For example, processing at a temperature less than 110 Celsius provides, in an exemplary aspect, a better hand to the material than at temperatures above 110 Celsius. As provided above, a polyester material may have a transitional temperature near 120 Celsius (or any temperature above 110 Celsius) and the encroachment on that transitional temperature for a period of time during the CO 2  process cycle changes the processed material&#39;s hand/feel. In yet a further aspect, operating at 100 Celsius for a polyester material results in a hand similar to that of a water-based dyeing process. Therefore, in exemplary aspects, CO 2  operations at 100 Celsius may be selected to result in a hand feel similar to that of a material finished in a water-based solution. 
     Cleaning Cycle Reduction/Elimination 
     Efficiencies at the precipitation of the finishing material realized in the processes described hereinabove allow for, in exemplary aspects, operating the CO 2  processes in a repeated manner without interviewing cleaning of the system between target material runs. For example, allowing the finishing material to precipitate as it is being perfused through the target material as opposed to when it is stagnant in proximity to the pressure vessel or other components therein limits the amount of finishing material maintained by the system (e.g., on the vessel walls, on the holding member of the target material) following the depressurization cycle (e.g., depressurization cycle  1812  of  FIG. 7 ). If the finishing material did have a greater maintaining potential to the system components, then a sacrificial cleaning material may be placed in the pressure vessel following a target material run and prior to another target material run. The purpose of the sacrificial cleaning material in exemplary aspects is to capture the residual finishing material that was maintained by the system components at the completion of the target material run. The process of cleaning the system by way of inserting the sacrificial cleaning material may require pressurizing the system and running at least a modified three-cycle CO 2  process to dissolve the residual finishing material in the SCF CO 2  to be transferred from the system surfaces to the sacrificial cleaning material. Additionally (or alternatively) a cleaning process may rely on one or more chemical solvents (e.g., acetone) to transfer the residual finishing material. Therefore, environmental, time, and energy resources may be saved by reducing the use of a cleaning cycle between target material runs. The elimination or reduction of cleaning cycles between runs may be realized through the maintaining of flow rate at a non-zero value as the finishing material is precipitating from the CO 2 . Additionally, it is contemplated that the maintaining of a temperature above a threshold value until the finishing material precipitates out of the CO 2  also reduces or eliminates the need for a subsequent cleaning process. For example, as described above, if the target material is a polyester material, maintaining the temperature above 100 Celsius keep pores of the polyester open a sufficient amount for maintaining of finishing materials (e.g., dyestuff) within the polyester as the pressure decreases causing the dyestuff the precipitate out of the CO 2 . Allowing the pores of the polyester to stay sufficiently open during the precipitation phase limits that residual accumulation of finishing material on components of the pressure vessel and system, in an exemplary aspect. 
     Therefore, it is contemplated that a series of cycles in a pressure vessel may include the insertion of a first target material into the pressure vessel, a first pressurization cycle, a first dyeing/treatment cycle, a first depressurization cycle, removal of the first target material, insertion of a second target material, a second pressurization cycle, a second dyeing/treatment cycle, a second depressurization cycle, and removal of the second target material. Absent from this sequence of event is the insertion of a sacrificial cleaning material and cycles of pressurization—dyeing/treatment/cleaning—depressurization with the sacrificial material. The elimination of these steps in the process saves, time, energy, and the sacrificial cleaning material. 
     A sacrificial cleaning material may be a material of similar composition to that of the target material. However, a lesser quantity of the sacrificial material may be used than the target material. For example, the target material may be 100-200 Kg of material. The sacrificial cleaning material may be less than 100 Kg of material. Further, while the cycles of treatment for a target material are selected to achieve a desired finish on the target material, the cycles of a cleaning process are instead selected to reduce the residual finishing material on the system surfaces regardless of the sacrificial cleaning material finish outcome. Another distinction between a sacrificial cleaning material and a target material is that additional finishing materials are not generally included in the CO 2  process involving the sacrificial cleaning material. Further, inclusion of nominal finishing materials at a concentration disproportionate (e.g., 1-20%) of that used in connection with a target material could still be considered a sacrificial cleaning material, in exemplary aspects. Therefore, a sacrificial cleaning material can be distinguished from a target material as the finish of the material is not the primary purpose of the inclusion of the sacrificial cleaning material in the pressure vessel, in exemplary aspects. 
     Target Material Scouring 
     Scouring is a process of preparing a target material for eventual finishing by the SCF process. For example, scouring removes oils and oligomers from the target material. The oils and oligomers, if allowed to remain in association with the target material, can affect a dyeing process. Therefore, the oils and oligomers are traditionally removed in a water-based scouring process prior to dyeing of the target material. Aspects herein use a SCF environment to scour a target material, such as a rolled good or a spooled good. A SCF scouring process reduces water usage and potential environmental impact as a result of the waterless implementation provided by a SCF, such as SCF CO 2 . 
     SCF scouring uses an operating environment similar to that provided above with respect to the SCF dyeing implementations. For example, a pressure vessel, such as an autoclave, may be used to pressurize and heat a gas to achieve a SCF state. Unlike dyeing, however, scouring is focused on removing elements (e.g., oligomers, oils) from the target material rather than introducing elements (e.g., dyestuff) to the target material. As such, some of the elements of the system may be utilized differently for scouring rather than dyeing. For example, a pump system that introduces and captures CO 2  from within the pressure vessel may be used during the scouring process to extract CO 2  and elements removed from the target material. This pump system is referred to herein as an external pump as the external pump is effective to circulate material (e.g., CO 2 ) between the internal pressure vessel and an external location, such as a CO 2  reservoir and filter. Aspects contemplate extracting CO 2  having scoured elements, such as oligomers and oils, from the pressure vessel to the external location. The extracted CO 2  may be filtered or otherwise treated to remove the extracted scoured elements from the CO 2 . Additionally, it is contemplated that a surfactant may be added to the processes to aid in the bonding between the SCF CO 2  and the oligomers and/or oils. Additionally, it is contemplated that a sacrificial material is included with the target material such that the scoured elements, once removed from the target material, have a greater affinity for the sacrificial material allowing the scoured elements to transfer from the target material to the sacrificial material. 
       FIG. 16  depicts a flow chart representing an exemplary method of scouring a material with supercritical fluid, in accordance with aspects hereof. At a block  1602  a target material is positioned in a pressure vessel. The target material may be any material. For example, the material may be polyester, polyester blends, cotton, and the like. Further, the material may be a rolled good (e.g., rolled knit or woven fabric) and/or a spooled good (e.g., yarn, thread). The material may be positioned within the pressure vessel in any manner, such as those discussed above with respect to dyeing. 
     At a block  1604 , CO 2  is introduced within the pressure vessel. An external pump may transmit the CO 2  from an external source, such as a holding tank, to the internal volume of the pressure vessel. The CO 2  may be in any state, such as gas or liquid as it is introduced. The CO 2  is brought to at least a SCF state at a block  1606 . As previously discussed herein, the CO 2  may be heated and pressurized to prescribed levels to achieve a sufficient scour operation. 
     The target material is perfused with the SCF CO 2  at a block  1608 . Unlike SCF dyeing of the target material, the perfusing of the target material with SCF CO 2  in the scouring process has intent to remove unwanted elements from the target material. In some example, the pressure vessel may also include a surfactant or other material that aids in the bonding of the scoured elements with the SCF CO 2 . The surfactant or other materials are selected from those materials that will have a known or no impact on subsequent dyeing (e.g., finishing) of the target material. An internal pump may be activated to circulate the SCF CO 2  in order to perfuse the target material, in a manner similarly described above with respect to the SCF dyeing of a material. 
     At a block  1610 , the SCF CO 2  is exchanged from the pressure vessel while maintaining the pressure vessel in a condition to achieve a SCF state of the CO 2 . An external pump may be activated to cause the exchange. The external pump may remove a quantity CO 2  that is passed through one or more traps or filters effective to remove the scoured elements from the CO 2 . The external pump may reintroduce CO 2  (the same or different CO 2 ) within the pressure vessel. As such, the exchange of CO 2  allows for a scrubbing of the working CO 2  to extract the scoured elements from the pressure vessel. The exchange of the CO 2  containing the scoured elements prevents, in some examples, the scoured elements from accumulating on the pressure vessel during the scouring process. 
     At a block  1612 , scoured elements are removed from the extracted CO 2 . The CO 2  may pass through a trap or filter processes to remove the oligomers and/or oils from the CO 2 . This allows the CO 2  to be recycled and eventually introduced back into the pressure vessel. As such, the method of  FIG. 16  depicts a return to the block  1608 , which may represent a continued perfusing of the target material even as the CO 2  is at least partially filtered and returned to the pressure vessel. However, it is contemplated that the pressure vessel is a closed system during the scouring process and the CO 2  is only removed from the pressure vessel at the completion of the scouring process, in an exemplary aspect. 
       FIG. 17  depicts a flow chart representing an exemplary method of scouring and treating (e.g., dyeing) a material in a continuous process using SCF, in accordance with aspects hereof. In general, the method of  FIG. 17  includes two primary portions, a scouring portion  1702  and a dyeing (e.g., finishing) portion  1704 . The scouring steps  1702  and the dyeing steps  1704  may be performed in a continuous operation. This is in contrast to traditional scouring that may require unrolling a rolled good through a water bath that scours the material, drying the material, and then rerolling the material for a subsequent dyeing process. A SCF environment allows for a target material (e.g., roll or spool) to be positioned in a pressure vessel, as depicted in a block  1706  of the scouring steps  1702 . 
     A pressurization phase of the scouring process is initiated, as depicted at a block  1708 . A scouring phase of the scouring process is initiated at a block  1710 . A depressurization phase of the scouring is initiated within the pressure vessel at a block  1712 . As provided herein, the various phases of the scouring process may be adjusted based on the material, conditions, or other factors. 
     Without removing the target material from the pressure vessel, in an exemplary aspect, the dyeing steps  1704  may be performed following the completion of the scouring steps  1702 . In an alternative aspect, the target material may be removed from the pressure vessel to introduce a finishing material (e.g., dyestuff). Once the finishing material is introduced to the target material (e.g., a sacrificial material having the dyestuff placed in contact with the target material), the target material may be repositioned in the pressure vessel for the dyeing steps  1704  to be completed. Therefore, it is contemplated that a transition from a SCF scouring to a SCF dyeing process may be achieved with minimal disruption and substantially continuous in nature. 
     At a block  1714 , finishing material is introduced into the pressure vessel with the target material. The finishing material may be introduced in any manner contemplated herein for dyeing. At a block  1716 , a pressurization phase of the dyeing process is initiated within the pressure vessel. At a block  1718 , a dyeing phase of the dyeing process is initiated within the pressure vessel. At a block  1720 , a depressurization phase of the dyeing process is initiated within the pressure vessel. At a block  1722 , the target material is removed from the pressure vessel.  FIG. 17  provides for the target material to be scoured by a SCF process in the scouring steps  1702  and then subsequently dyed using SCF in the dyeing steps  1704 , in accordance with aspects hereof. 
       FIGS. 23-26  depict relative variables during cycles of SCF scouring, in accordance with aspects hereof. The cycles may include, but are not limited to, a pressurization cycle  2308 , a scouring cycle  2310 , a rinsing cycle  2311 , a depressurization cycle  2312 , and a completion cycle  2314 . The scouring cycle  2310  and the rinsing cycle  2311  may be a common cycle in some aspects provided herein. The variables, similar to those discussed with respect to SCF dyeing include temperature  2302 , pressure  2304 , internal flow rate  2306 , and external pump  2307 . As with the  FIGS. 18-22  discussed previously, the depiction of the variables are for illustration purposes and are not to scale. Further, it is contemplated that values and configurations provided with respect to dyeing processes herein may be applied to scouring processes in aspects. Therefore,  FIGS. 23-26  are exemplary in nature and not limiting as to configurations of variables. 
       FIG. 23  provides an exemplary depiction of variables for a SCF scouring process, in accordance with aspects hereof. For example, the temperature  2302  may start at about 80-90 Celsius and the external pump  2307  may be on, and the internal flow rate may be increased to about 240 m 3 /hr in the pressurization cycle  2308 . This configuration allows for the CO 2  to be circulated relative to the target material as the pressure and temperature increase to appropriate levels for the scouring cycle  2310 . During the scouring cycle  2310 , the external pump  2307  is turned off while temperature, pressure, and the internal flow rate are maintained. The scouring cycle  2310  may operate for any duration of time (e.g., 15, 30, 45, 60, 75, 90, 105, 120 minutes). In an exemplary aspect the scouring cycle operated for at least 60 minutes. The rinsing cycle  2311  continues to maintain temperature (e.g., 100-125 Celsius), pressure (200-250 bars), and internal rate flow (e.g., 90-240 m 3 /hr) relatively constant, but the external pump  2307  is initiated again. The use of the external pump  2307  may exchange the CO 2  and extract scoured elements (e.g., oligomers, oils) from the pressure vessel to rinse the system of the scoured elements prior to changing the state of the CO 2 . The rinsing cycle  2311  may operate for any time (e.g., 15, 30, 45, 60, 75, 90 minutes). In an exemplary aspect, the rinsing cycle  2311  is about 30 minutes. The depressurization cycle  2312  drops the temperature, pressure, and internal flow rate, in this example. The total time may be adjusted based on the target material characteristics and/or the amount of scouring to occur. 
       FIG. 24  provides an exemplary depiction of variables for a SCF scouring process, in accordance with aspects hereof. Specifically, a separate rinsing cycle is omitted in this example. Further, the external pump  2307  operates only in the pressurization cycle  2308  and not in the other scouring cycle  2310  or the depressurization cycle  2312 , in this example. In an exemplary scenario, the internal flow rate  2306  may operate in a 90-130 m 3 /hr range during the pressurization cycle  2308 , increase to a 175-240 m 3 /hr range during the scouring cycle  2310 , and decrease to a 90-130 m 3 /hr range during the depressurization cycle  2312 , in an exemplary aspect. The pressure  2304  may achieve 250 bar in the scouring cycle  2310  and decrease to 130 bar in the depressurization cycle  2312 . As with the dyeing process, any rate of depressurization may be used. In an exemplary aspect 5 bar/min is applied for a depressurization. 
       FIG. 25  provides an exemplary depiction of variables for a SCF scouring process, in accordance with aspects hereof. In this example, the internal flow rate  2306  may be maintained during the scouring cycle  2310  and the depressurization cycle  2312 . Further, the external pump  2307  may be on during the pressurization cycle  2308  as well as the depressurization cycle  2312  (while being off during the scouring cycle  2310 ). 
       FIG. 26  provides an exemplary depiction of variables for a SCF scouring process, in accordance with aspects hereof. In this example, the internal flow rate may be varied among the different cycles while the external pump  2307  is activated during the pressurization cycle  2308  and the depressurization cycle  2312  while being inactive during the scouring cycle. 
     Therefore, it is contemplated that any combination and value of variables may be applied during the SCF scouring process. For example, the temperature, pressure, flow rate, time, and external pump may all be adjusted during each of the cycles to achieve a degree of scouring appropriate for a target material and subsequent process, such as dyeing of the target material. Further yet, the variables discussed with respect to SCF dyeing herein may equally apply to SCF scouring. For example, the combinations of variables for pressurization cycle of SCF dyeing may be applied in some aspects of pressurization cycle of the SCF scouring; combinations of variables for dyeing cycle of SCF dyeing may be applied in some aspects of the scouring cycle of the SCF scouring; and combinations of variables for the depressurization cycle of SCF dyeing may be applied in some aspects of the depressurization cycle of SCF scouring. 
     It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims. 
     While specific elements and steps are discussed in connection to one another, it is understood that any element and/or steps provided herein is contemplated as being combinable with any other elements and/or steps regardless of explicit provision of the same while still being within the scope provided herein. Since many possible embodiments may be made of the disclosure without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.