Abstract:
A commercially viable paper wrapped foam cup comprising a taper portion that prevents the shrinkage-induced curling from interfering with the un-nesting of nested paper wrapped foam cups. The paper wrapped cup further comprises a fillet for strengthening the cup foot to retard shrinkage-induced curling of the foot. The paper wrapper has abutting to overlapping opposing ends to completely hide the foam cup to enhance the visual appearance of the cup. The overlapping portions of the paper wrapper are not bonded to each other to prevent wrinkling of the paper wrapper as the cup shrinks. A machine and corresponding method provide for automatically supplying foam cups and paper wrappers, wrapping the paper wrapped cup, and stacking the wrapped cups.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority from U.S. provisional application 60/521,359, filed Apr. 8, 2004. 
    
    
     FIELD OF THE INVENTION 
     In one aspect, the invention relates to a paper wrapped foam cup. In another aspect, the invention relates to a method for automatically assembling a paper wrapped foam cup. 
     DESCRIPTION OF THE RELATED ART 
     Paper wrapped foam cups, while known in the art, currently comprise a small portion of the beverage cup market compared to foam-only cups, even though the paper wrapped foam cups have similar insulating qualities of the foam-only cups and are much better suited for printing on the exterior of the cup. 
     Prior paper wrapped foam cups generally comprise a traditionally made foam cup in combination with a paper layer that is wrapped about and bonded to the exterior of the foam cup. The paper can be pre-printed with any desired image or text prior to the wrapping of the paper to the exterior of the foam cup. It is much easier to print on the paper than on the exterior of the foam cup. The quality of printing on the paper is superior to printing on foam. 
     In addition to superior printing characteristics, for a given total wall thickness, a paper wrapped foam cup has greater hoop strength, resulting in a more rigid cup that better resists radial deflection and greater columnar strength. The greater rigidity and columnar strength reduces the possibility that the cup will radially collapse in response to a consumer squeezing the cup or collapse when lidded. 
     Many consumers also find the paper wrapped foam cups aesthetically more pleasing both in visual appearance and in feel, to a foam only cup. They also perceive the paper wrapped foam cup to be of a higher quality and have a greater panache. Paper wrapped foam cups can be, under certain circumstances, more cost effective to make than foam-only cups and conventional paper hot and cold cups. 
     Yet, even with all of these advantages, paper wrapped foam cups comprise only a very small portion of the hot and cold beverage cup market. Therefore, there is still a strong desire and need within the beverage cup market for a commercially viable paper wrapped foam cup. 
     SUMMARY OF THE INVENTION 
     In one aspect, the invention relates to a wrapped foam cup comprising an expanded foam cup having a wrapper. The expanded foam cup comprises a bottom wall and a peripheral wall extending away from the bottom wall. The bottom wall has an upper surface and a lower surface. The peripheral wall has an inner surface and an outer surface. Collectively, the upper surface and inner surface define a beverage cavity. The peripheral wall terminates in a top edge that defines an opening to the beverage cavity. The wrapper is wrapped around and bonded to the outer surface of the cup and has opposing ends connected by an upper edge and a lower edge. The upper edge is located near the top edge of the cup. The peripheral wall has a first portion with a first taper and a second portion with a second taper, which is greater than the first taper. 
     In another aspect, the invention relates to a wrapped foam cup comprising an expanded foam cup having a wrapper. The expanded foam cup comprises a bottom wall and a peripheral wall extending away from the bottom wall. The bottom wall has an upper surface and a lower surface and the peripheral wall has an inner surface and an outer surface. The upper surface and inner surface define a beverage cavity and the peripheral wall terminates in a lip that defines an opening to the beverage cavity. The wrapper is wrapped around and bonded to the outer surface of the cup. The wrapper has opposing ends connected by an upper edge and a lower edge, with the upper edge adjacent the lip of the cup. The peripheral wall has an upper taper portion extending to the lip and the upper taper portion is tapered such that the shrinkage of the expanded foam cup would not cause the lip to interfere with the un-nesting of nested similar wrapped foam cups. 
     In yet another aspect, the invention relates to a method for automatically assembling a wrapper to an outer surface of a pre-made foam cup to form a wrapped foam cup. The method comprises:
     (1) automatically supplying a pre-made expanded foam cup;   (2) automatically supplying a wrapper sized to be wrapped about an exterior of the foam cup;   (3) heating the wrapper to a temperature where the wrapper will bond to the exterior of the foam cup;   (4) automatically wrapping the wrapper about the exterior of the foam cup to effect the bonding of the wrapper to the exterior of the foam cup;   (5) repeating steps 1-4 multiple times to form multiple wrapped cups; and   (6) automatically assembling at least some of the multiple wrapped cups into a group suitable for subsequent handling.   

     In yet one other aspect, the invention relates to an apparatus for automatically assembling a wrapper to a foam cup to form a wrapped foam cup. The apparatus comprises a rotating platen having multiple carriers, with each carrier sized to support a wrapper. A heater is provided for heating the wrapper to a bonding temperature. A rotating mandrel assembly comprises multiple rotatable mandrels, with each of the mandrels supporting a different cup. The rotating platen and rotating mandrel assembly are arranged relative to each other such that upon their relative indexed rotation a rotatable mandrel is effectively rolled over the surface of a carrier to effect the wrapping of a wrapper on the carrier about a cup on the mandrel. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1 and 2  are enlarged sectional views of a pair of stacked paper wrapped foam cups illustrating a shrinkage-induced stacking problem overcome by the invention.  FIG. 1  illustrates the stacked cups in a post-wrapped, pre-shrunk state and  FIG. 2  illustrates the stacked cups in a shrunken state. 
         FIG. 3  is a perspective view of a paper wrapped foam cup according to the invention that overcomes the shrinkage-induced stacking problem associated with the paper wrapped foam cups. 
         FIG. 4  is a side view of the paper wrapped foam cup of  FIG. 3 . 
         FIG. 5  is a sectional view taken along line  5 - 5  of  FIG. 4 . 
         FIG. 6  is a top view of the paper wrapped foam cup of  FIG. 4 . 
         FIG. 7  is a bottom view of the paper wrapped foam cup of  FIG. 4 . 
         FIG. 8  is an enlarged view of a pair of stacked paper wrapped foam cups of  FIG. 4  in the post-wrapped, pre-shrunk state. 
         FIG. 9  is an enlarged view of a pair of stacked paper wrapped foam cups of  FIG. 4  in the shrunken state. 
         FIG. 10  is a schematic of an assembly machine suitable for assembling any paper wrapped foam cup, especially the paper wrapped foam cup of  FIG. 4 . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     It should be noted that while the below description references specific dimensions for the paper wrapped foam cup, the drawings are not necessarily to scale. To clearly illustrate some of the features of the paper wrapped foam cup some portions of the drawings have been exaggerated. 
     While working on developing a commercially successful paper wrapped cup, the current inventors encountered a previously unknown problem for paper wrapped cups. A solution to the problem is necessary to make a commercially successful cup. The problem finds its origin in that the foam most commonly used for paper wrapped foam cups is expanded polystyrene foam. After a possible post-molding expansion, such foam is known to shrink over time after the completion of the molding process. With prior foam-only cups, the shrinkage never posed a problem as the foam-only cup was unrestrained in all dimension and could therefore simultaneously shrink in all dimensions. In other words, all portions of the foam-only cups shrunk substantially to the same extent, thus keeping the cup proportions generally constant. 
     Such is not the case with the paper wrapped foam cups.  FIGS. 1 and 2  illustrate a paper wrapped foam cup  10  comprising a foam cup  12  and a paper wrapping  14  that extends from just beneath a lip  16  to almost the tip of a foot  18  extending away from a bottom  20  of the cup. It has been found that the addition of the paper wrapping  14  bonded to the foam constrains the shrinking of the foam in contact with the paper wrapping  14 . The portions of the foam not in contact with the paper tend to shrink as they would otherwise. Since the foam shrinks in all three dimensions except for where it is in contact with the paper, the lip  16  tends to curl inwardly from its pre-shrunk position ( FIG. 1 ) to project radially inwardly in its shrunken state ( FIG. 2 ). 
     The curling of the lip  16  is very detrimental to the separation of the nested cups. It is common to design cups such that they can stack or nest within each other while leaving an air gap  24  between the stacked cups. The air gap  24  aids in the subsequent separation of the cups by preventing the frictional interaction between the walls of the nested cups and preventing a low pressure area from forming between the bottoms  20  of the nested cups upon the withdrawal of one of the cups. The air gap  24  is normally designed such that upon the inverting of the cups, the nested cup will fall out of the outer cup. A typical air gap is about 0.015 inches. With this structure, nested cups can easily be separated which is very important, especially in high volume environments, such as fast food restaurants, or in automated beverage dispensing systems, which can jam when the cups do not properly separate. 
     The curling of the lip  16  can be great enough to result in the lip projecting radially inwardly a distance greater than the air gap  24 , causing a nesting cup to contact the curled lip  16 , creating frictional resistance between the curled lip  16  and the nesting cup paper wrapping  104 . If the force used to nest the cup  10  is great enough to deflect either or both the curled lip  16  and the sidewall of the outer cup, the inherent resiliency of the foam applies a compressive force from the curled lip against the sidewall of the outer cup. Either of the frictional resistance or the compressive force is great enough to hold the cups in the nested condition when inverted. 
     The curling also can negatively impact the stacking height of the nested cups, which ultimately increases the shipping costs of the cups. The curling can prevent a nesting cup from being completely inserted into another cup. Such a condition increases the stack height of a given number of cups. The increased stack height means that a greater volume or “cube” is required for a given number of cups, which reduces the total number of cups that can be shipped in a fixed volume container, resulting in increased shipping costs. The shipping cost of beverage cups is a significant portion of the overall cost of the cup. It is highly desirable to minimize the shipping costs. Therefore, it is highly desirable to stack the cups in a manner such that as many cups as possible can be fit within a given cube. 
     The paper wrapped foam cup  100  illustrated in  FIGS. 3-9  addresses the problems associated with the shrinkage-induced curling of the lip for a paper-wrapped cup. The paper wrapped foam cup  100  comprises a foam cup  102  that is wrapped by a paper wrapper  104 . The foam cup  102  comprises a peripheral sidewall  106  that extends from a bottom wall  108  and terminates in a radially projecting lip  110 . The bottom wall  108 , sidewall  106  and lip  110  define an open-top beverage cavity  112  that is accessible through the open top defined by the lip  110 . 
     A foot  114  extends downwardly from the bottom wall  108 . The foot  114  can be thought of as an extension of the sidewall  106 . A shoulder  116  extends radially into the beverage cavity  112  from the sidewall  106 . The shoulder  116  cooperates with the foot  114  of a nesting cup to limit the extent of the insertion of the nesting cup. 
     A fillet  118  extends between the foot  114  and the bottom wall  108 . As illustrated, the fillet  118  is integrally formed with the foot  114  and the bottom wall  108  and extends continuously along the foot  114  and bottom wall  108  to form an annular shape. The fillet  118  defines an annular surface  119 , which is shown having a 45 degree angle relative to the vertical. Other angles are within the scope of the invention. 
     The sidewall  106  has an outer surface  120  with a constant taper preferably extending from the foot  114  to the lip  110 . As illustrated, the constant taper of the outer surface  120  defines a 7.79 degree acute angle relative to the vertical. In contrast, the sidewall  106  has an inner surface  122  with a constant taper portion  124  and a variable taper portion  126 . As illustrated, the constant taper portion  124  defines the same angle, relative to the vertical, as the outer surface  120  (although the constant taper portion could define a different angle) and extending from the shoulder  116  to the variable taper portion  126 , resulting in the sidewall  106  having a constant thickness along the extent of the constant taper portion  124 . 
     The variable taper portion  126  extends from below the lip  110  up to, and preferably, although not necessarily, including the lip  110 . As illustrated the variable taper portion  126  generally forms an acute angle of 9.64 degrees relative to the vertical. For manufacturing purposes, the transition from the constant taper portion  124  to the variable taper portion  126  is effected by a radius  128 , instead of a line, which as illustrated has an arc defined by an angle of 1.84 degrees. For purposes of this disclosure, the radius is treated as part of the variable taper portion  124 . 
     Since the angle of the variable taper portion  126  is greater than the angle of the corresponding portion of the outer surface  120 , there is a constant reduction in thickness of the sidewall  106  along the extent of the variable taper portion up to the lip  110 . Preferably, the variable taper portion  126  extends along the lip  110  up to the top edge of the cup  100 . 
     The benefit of the variable taper portion  126  is that it increases the air gap between stacked cups along the variable taper portion as compared to the air gap along the constant taper portion  124 . This is best seen in  FIG. 8 , which illustrates two freshly wrapped stacked cups  100 , which define an air gap  130 . The air gap  130  along the variable taper portion  126  increases relative to the air gap  130  along the constant taper portion  124 . Along the constant taper portion  124 , the air gap  130  is approximately 0.015 inches. At the top edge of the cup along the variable taper portion, the air gap is approximately 0.25 inches. Referring to  FIG. 9 , as the cups  100  shrink over time, the lips  110  curl as previously described. The curling reduces the air gap  130  at portions of the variable taper portion  124 . However, the reduction of the air gap  130  related to the curling is not great enough to close the air gap  130 , thereby preventing the curling lip  130  from contacting the nested cup and interfering with the separation of the stacked cups and/or the stacking of the cups. 
     While the variable taper portion  126  is illustrated as a single planar surface or facet having a constant acute angle relative to the vertical (ignoring the radius  128 ), it is within the scope of the invention for the variable taper portion to comprise multiple facets. Each of the facets can form a different angle relative to the vertical. The variable taper portion  126  can also be formed by a continuous radius or multiple radii. Additionally, the variable taper portion  126  can be formed by a combination of facets and radii. 
     Whichever structure is used to create the variable taper portion  126 , it is important that the resulting variable taper portion  126  create a sufficient air gap  130  along the variable taper portion such that any shrinkage-induced curling of the lip  110  does not close off the air gap  130  to a point sufficient to hinder separation. This will ensure that the shrinkage does not interfere with the separation and stacking of the cups  100 . 
     While not a limitation on the invention, it is preferred that the variable taper portion  126  be selected such that the width (Dimension A,  FIG. 5 ) of the lip along the upper edge be the same dimension as that found on similar sized foam-only cups as this will permit current lids for the foam-only cups to be used on the paper-wrapped foam cups  100 . 
     The foot  114  of the cup  100  is potentially subject to the same shrinkage-induced curling as the lip  110 . If the foot  114  were to curl a sufficient amount that the foot  114  did not rest on the shoulder  116  of another cup when stacked, it would have a devastating impact on the stacking and separation of the cups. However, the additional strength and material mass provided by the fillet  118  sufficiently controls any curling of the foot  114 . The fillet  118  is further beneficial in that it provides additional structure support for the foot  114  against pressure applied to the foot  114  during the wrapping process. Unlike the sidewalls of the cup which are internally supported by a mandrel during wrapping, the interior of the foot  114  is unsupported. The ability to apply pressure to the foot  114  without fear of the foot  114  collapsing enhances the adhesion of the paper wrapper  104  to the foot  114 , which reduces the likelihood that the paper will buckle or wrinkle at the foot  114 . 
     For reference purposes, it should be noted that the dimensions for the cup relate to a 16 oz cup made from expanded polystyrene foam having a density of approximately 3.28 lb/ft 3  and a sidewall thickness along the constant taper portion  124  of approximately 0.082 inches. These cup parameters can vary with cup size. For example, the sidewall thickness often varies with the volume of the cup. The greater the volume, the greater the wall thickness to help structurally support the additional beverage volume. All else being equal, the sidewall thickness of a paper wrapped foam cup is less than a foam-only cup because of the extra strength provided by the paper. 
     While the structure of the foam cup related to controlling the shrinkage-induced curling greatly contribute to creating a commercially successful paper-wrapped foam cup, the paper wrapper  104  has features that also contribute to a commercially successful paper-wrapped cup. Preferably, the paper wrapper  104  extends substantially from the lip  110  to the bottom of the foot  114 . For ease of assembly, the paper wrapper  104  preferably stops approximately 0.030 inches from the lip  110  and 0.030 inches from the bottom of the foot  114 . Even with the 0.030 inch gap between the paper and the lip  100  and foot  114 , when a lid is placed on the cup  100 , the cup  100  has the appearance of a paper-only cup since almost all of the foam is hidden from the consumer. 
     The paper wrapper  104  completely circumscribes the cup  110  and has opposing ends  140  and  142  ( FIG. 4 ), with one of the ends (illustrated as end  140 ) butting to overlapping the other end. The overlap is beneficial in that it ensures that no portion of the foam cup  102  is visible, which is aesthetically superior for most consumers, who perceive it as a higher quality cup. It is preferred that the overlap does not exceed 0.040 inches. Overlaps of less than this amount have shown the least tendency to wrinkle. 
     For a preferred paper, such as 40 lb Capri Gloss made by Stora Enso, which has a thickness of approximately 2 mils, the overlap preferably ranges from abutting to less than approximately 40 mils. The combination of paper thickness and the extent of overlap results in the consumer not being able to feel the overlapped portion, which also enhances the aesthetics of the cup  100 , adding to the commercial success of the cup  100 . 
     It is preferred that the overlapping portion of the paper wrapper  104  is not bonded to the underlying portion of the paper wrapper  104  to prevent the formation of any wrinkles in the paper wrapper  104  along the overlapping portion in response to the shrinkage of the cup  102 . It is also preferred that the overlap is less than 0.040 inches to reduce the possibility of wrinkling. 
     The paper can be any suitable type of paper. For example, it can be coated or uncoated. It can be fiber-based or polymer-based. It can be a single layer or multiple layers. The paper can have suitable bonding materials incorporated into the coating as does the Capri Gloss made by Stora Enso. Alternatively, a specially selected bonding material, such as an adhesive, can be added to the paper as part of wrapping of the paper to the cup. The specific adhesive is not germane to the invention. 
       FIG. 10  illustrates a schematic of an assembly machine  200  suitable for assembling the paper wrapped cup  100 . In general, the assembly machine  200  comprises a paper roll  202  comprising a web of paper  204  on which are printed multiple paper wrappers  104 . The web  204  is fed through a punch assembly  206  that punches the paper wrappers  104  from the web  204 , with the skeleton of the punched web being fed to a take up roll  205 . The punched paper wrappers  104  are then picked up by a reciprocating arm  208  and placed on a rotation platen  210 , which carries the paper wrappers  104  to a rotating mandrel assembly  212  where the paper wrappers  104  are wrapped about a foam cup. The mandrel assembly  212  is fed pre-made foam cups from an escapement  216 . A cup out-feeder  218  receives and stacks the wrapped cups  100 . 
     Looking at the assembly machine in greater detail, the punch assembly  206  is preferably a traditional punch and die. The reciprocating arm  208  comprises a pick up  222 , which is conveniently shaped to correspond to the shape of the paper wrapper  104 . The pick up  222  also comprises several air passages through which pressurized air or a vacuum can be applied to the paper wrapper  104  to aid in the picking up and releasing of a paper wrapper  104 . 
     The rotating platen  210  comprises multiple spaced carriers  226 , each one sized to support a paper wrapper  104 . The spacing between the carriers  226  is great enough to permit the passage of the mandrel assembly  212 . Preferably, each of the spaced carriers has a series of air passages  228  such that either a vacuum or pressurized air can be applied to the paper wrapper  104  to aid in holding the paper wrapper  104  to the carrier  226  or removing the paper wrapper  104  from the carrier. 
     The mandrel assembly  212  comprises a rotating hub  230  from which extend multiple spokes  232 . A mandrel  214  is rotatably mounted to each of the spokes such that the mandrel  214  can rotate about the longitudinal axis of the corresponding spoke  232 . Each mandrel  214  comprises multiple air passages  236  through which either pressurized air or a vacuum can be applied to a foam cup  102  carried by the mandrel to aid in the holding or releasing of the cup to and from the mandrel  214 . External pressurized air nozzles  238  aid in the removal of the wrapped cups  100  by providing a blast of pressurized air to blow the cup  100  off of the mandrel  214 . 
     The escapement  216  is well known in the industry and comprises a chute  240  in which is received a stack of foam cups  102 . Any one of several well known cup feed mechanism can be used to release one cup  102  at a time onto a mandrel  214  positioned beneath the chute  240 . Known cup feed mechanisms include rotating screws and cams. The type of feed mechanism is not germane to the invention. 
     The out-feeder  218  comprises a cup receiving chute  250  partially defined by a series of rollers  252  and guide plates  254 . The rollers  252  are preferably brush rollers, with at least the first upper and lower rollers being drive rollers. The drive rollers can be rotated to propel a cup received between the drive rollers further into the chute. 
     While not shown, a controller is provided to synchronize the movement of the various elements of the assembly machine  200 , including the actuation of the various air pressure and vacuum supplies. A suitable controller would be a programmable logic controller. 
     In operation, the web  204  is advanced from the paper roll  202  through the punch assembly  206  and onto the take up roll  205 . As the web  204  passes through the punch assembly  206 , the individual paper wrappers  104  are punched from the web  204 . 
     The pick up  222  of the reciprocating arm  208  is lowered onto the punched paper wrapper  104  and the vacuum is applied to the pick up  222  to hold the paper wrapper  104  to the pick up  222 . The reciprocating arm  208  then moves such that the pick up  222  is positioned above a carrier  226 . The reciprocating arm  208  is then lowered to bring the pick up  222  into contact with the carrier  226 . The vacuum to the pick up  222  is stopped and vacuum is then applied to the carrier  226  to transfer the paper wrapper  104  to the carrier  226 . 
     The paper wrapper  104  is then heated while it is on the carrier  226 . The heating can be accomplished by providing an external heater that radiates heat onto the paper wrapper  104 . Preferably, the carriers  226  are directly heated, such as by a resistive heating element. Thus, the paper wrapper  104  is heated as the carrier  226  is rotatably indexed to the mandrel assembly  212 . 
     Preferably, the temperature of the carrier plate is between 375° and 400° F. and the paper wrapper  104  sits on the carrier  226  for between 8 to 15 seconds. Testing has shown that this temperature and time combination is sufficient to heat the paper wrapper  104  such that the bonding materials in the preferred paper are suitable for bonding to the foam cup  102 . For the previously described preferred paper, the preferred temperature is 400° F. and the time to wrap the paper wrapper is 1-3 seconds. In some tests, plate temperatures of 440° were needed to obtain the desired degree of adhesion. 
     As the platen  210  is rotated, the carrier  226  is ultimately brought into position with one of the mandrels  214  on which a cup  102  is being carried. The platen  210  and mandrel assembly  212  are indexed such that the cup-carrying mandrel  214  is brought into contact with the leading edge of the carrier  226 . With the cup-carrying mandrel  214  remaining in this position, the platen  210  continues to rotate beneath the mandrel  214 . Since the mandrel  214  is free to rotate relative to the spoke  232 , the rotation of the platen  210  effectively rolls the mandrel  214  and the cup  102  it is carrying along the paper wrapper  104 . In this manner the paper wrapper  104  is wrapped about the cup  102 . Once the carrier  226  passes from beneath the mandrel  214 , the mandrel  214  is positioned above the space between the carriers  226 . The mandrel assembly  212  then rotates the next mandrel into position to wrap another cup. 
     As the cup wrapping process continues, the wrapped cup  100  is eventually rotated into alignment with the chute  250  of the out-feeder  218 . At this time the vacuum to the mandrel  214  is replaced by pressurized air and the external air nozzles  238  hit the cup  100  with a blast of pressurized air. The pressurized air from the mandrel and the air nozzles  238  force the cup  100  off of the mandrel  214  and into the chute  250 . The drive rollers  252  are continuously activated to propel the expelled cup  100  further down the chute  250  and stack the cup  100  within any waiting cups. 
     As the cup wrapping process continues, the previously emptied mandrel is rotated beneath the escapement  216 . In this position, a vacuum is applied to the mandrel and the lowermost cup  102  of the stack is moved onto the mandrel  214  by the escapement  216 . 
     The process is repeated until the paper wrapping is completed. 
     While not shown, the out-feeder  218  can be coupled to a traditional packaging assembly line. In such situation, the cups  100  would be ejected from the chute  250  when a predetermined number were stacked therein. The ejected stack of cups  100  would then be automatically bagged and put into a suitable container for shipping. Preferably, the out-feeder  218  would stack the cups within a protective sleeve prior to ejection. 
     Similarly, the escapement  216  can be directly fed cups  102  from a traditional cup manufacturing line. The benefit of this configuration is that it is not necessary to inventory the cups prior to wrapping, which reduces space and capital requirements. In fact, the invention is ideally suited for immediately wrapping freshly made foam cups. Freshly made cups are subject to more curling than cups that have aged prior to wrapping. This is because the cups immediately begin shrinking, subject to some temporary post-molding expansion, after they are made. Cups that are permitted to age prior to wrapping will have less curling since the cup is permitted to shrink in all dimensions. While the wrapping of sufficiently aged cups is one way to minimize curling, given the large production volumes used in contemporary cup molding facilities, it is not cost effective to provided the needed capital and storage for the aged cups.