Abstract:
A method and device for releasably sealing a material into a container is disclosed. The device has a plug handle and a flexible plug body with an exterior edge that conforms to the contours of the interior wall of the container. The plug body is inserted into the container and is positioned to the surface of the material within the chamber using the plug handle. The plug body exerts resistance pressure against the interior wall of the container. The resistance pressure releasably seals the material in the chamber. In certain embodiments, while the plug body is inserted into the container, the resistance pressure squeezes the material from at least a portion of the interior wall of the container down to a pool of the material in the chamber of the container.

Description:
CROSS-REFERENCE TO RELATED APPLICATION none 
     FIELD 
     The present invention relates to the field of materials storage and particularly to sealing paint and other surface coatings for later use. 
     BACKGROUND 
     This invention relates to methods and devices which facilitate short to long term storage, using the original container or another container, of a material, such as a liquid or, more particularly, any type of interior or exterior latex or oil based paint, stain or other interior or exterior surface coatings. Note: “paint” is a general term used in this document to refer to all of the types of surface coatings referenced above. 
     The price of premium paint cost in excess of $50 per gallon. Having a convenient and cost effective way to preserve paint freshness for short or long periods of time protects this investment. Storing partially filled containers of paint for medium to long periods of time causes evaporation, and as a result, a paint skin forms on the surface. The evaporation problem is greatly accelerated in warm outdoor conditions, where paint is often stored in a secondary container for short periods of time on a project basis. Evaporation results in paint becoming thick and chemically compromised. The paint may be too thick to reconstitute and must be discarded, resulting in a waste of money and further stress on landfills or other methods of waste disposal. For oil based coverings, the air in the container may cause the paint to become oxidized, resulting in a thick skin of the coating to form on the surface. This may also result in the paint becoming chemically compromised and thickened. In addition, the skin that forms on the surface of the paint and on the interior wall of the paint can may fragment and contaminate the remaining paint, forcing the remaining paint to be discarded. 
     Various devices have been proposed in the art such as transferring unused paint to a separate storage container or removing the metal lid and replacing it with a flexible lid with a spout and seal. In addition, other devices have been proposed in which the air has been vacuumed out of a storage container. However, vacuums may accelerate evaporation, and so may not be suitable for use in storing paint, where evaporation may degrade the quality of the remaining paint. 
     It is assumed that these devices are useful for their intended purpose, however, these devices do not offer a convenient and relatively inexpensive way to preserve paint for short to long periods of time, whether or not they use the original product packaging, and in the case of the flexible or vacuumed lid, does not address the evaporation and oxidation issues from the air volume within the partially empty container. 
     Therefore, it is desirable to have a simple, easy to use paint plug device, which may be re-used many times and for many different types of paint or other coating materials, which does not require the expense and inconvenience of purchasing redundant and potentially expensive storage kits or containers, transferring the materials, or cleaning these containers before re-use. 
     SUMMARY 
     A materials storage device comprises a plug device, used to preserve materials for future use. The plug device may be used to store the material in its original container packaging for short or long term use, or may be used to preserve materials in an external container for short term projects. The plug device may be used to seal a material into a container having an interior bottom and an interior wall defining a chamber for holding the material. The plug device has a flexible plug body that is sized to be positioned within the container, and the plug body has an exterior edge that conforms to the contours of the interior wall of the container. The exterior edge is sized to simultaneously fit within the container at a top surface of the material within the chamber and to exert resistance pressure against the interior wall of the container for releasably sealing the material in the chamber. The device also has a plug handle section attached to the plug body and extending from the plug body to a free end. The plug handle section is arranged to facilitate inserting the plug body into the container to the top surface of the material within the chamber. 
     In certain embodiments, the cross-section of the chamber of the container is round. In others, the chamber of the container has a non circular cross-section, and the plug body is non-circular to accommodate the non-circular cross-section of the container. 
     In other embodiments, the plug body is sized to squeeze material from at least a portion of the interior wall of the container while the plug body is being inserted into the container, and to push the squeezed material into a pool of the material in the chamber of the container. In other embodiments, the plug body has at least one additional seal to facilitate the sealing of the container. In even further embodiments, the exterior edge of the plug body is sized to be slightly larger in size than the contours of the interior wall of the container. 
     In certain embodiments, the plug handle system has a strap attached to the plug body, while in others, the plug handle system has an extraction grip attached to the plug body. In other embodiments, the plug handle system has a height reference system for determining a depth of the material in the chamber of the container to facilitate positioning the plug body within the container. The height reference system may have a depth gage slidably disposed on a strap to represent a depth of the material in the chamber of the container, and the height reference system may have depth markings on a strap attached to the plug body to represent an extent to which the material is filling the chamber. 
     In certain embodiments, the plug body has an inflatable bladder to form the exterior edge of the plug body, a tube seal such as a check valve for receiving air pumped into the tube to inflate the bladder and for releasing air from the bladder to deflate it, and a seal inflation tube that extends between the bladder and the tube seal for transferring the air into and out of the bladder. 
     In certain embodiments, the plug body comprises a flexible segmented compressible tube; in others, the plug body and plug handle section are formed into a single integrated unit. In further embodiments, the device has a removable plug cover sized to at least partially cover the plug body and to form a barrier between the plug body and the material in the chamber of the container. 
     A method is also disclosed for releasably sealing a material into a container having an interior bottom and an interior wall defining a chamber for holding a quantity of the material. The method comprises providing a flexible plug body that is sized to be positioned within the container. The plug body has an exterior edge that conforms to the contours of the interior wall of the container and is arranged to exert resistance pressure against the interior wall of the container. The plug body is inserted into the container to a top surface of the material within the chamber; and resistance pressure of the plug body against the interior wall of the container releasably seals the material in the chamber. In certain embodiments, the resistance pressure is used to squeeze the material from at least a portion of the interior wall of the container while the plug body is being inserted into the container, and the squeezed material is pushed into a pool of the material in the chamber of the container. 
     In certain other embodiments, a height reference system is used to determine a depth of the material in the chamber of the container; the plug body is positioned within the container with reference to the determined depth. In further embodiments, at least a portion of the plug body may be releasably covered with a removable thin film to form a barrier between the plug body and the material in the chamber of the container. 
     This plug device and method of material storage is very adaptable and may be used to extend the shelf life of materials such as paint in their original containers or preserve the material for short periods of time by using the plug device in conjunction with a separate container. 
     Additional objects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed. 
     The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one (several) embodiment(s) of the invention and together with the description, serve to explain the principles of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1   a  is a perspective view of an exemplary material storage device  100 , also known as a plug device  100 , as removed from a material container such as a paint can  50 ; 
         FIG. 1   b  is a perspective sectional view of the plug device  100  and can  50  as shown in  FIG. 1   a;    
         FIG. 1   c  is a perspective view of the plug device  100  of  FIG. 1   a  as installed in the can  50 ; 
         FIG. 1   d  is a perspective sectional view of the plug device  100  and can  50  of  FIG. 1   c;    
         FIG. 2   a  is a sectional view of the plug body  120 ; 
         FIG. 2   b  is a top view of the plug body  120 ; 
         FIG. 2   c  is a sectional view of the primary seal  240  of the plug body  120 ; 
         FIG. 2   d  is a sectional view of the uninstalled plug body  120 ; 
         FIG. 2   e  is a sectional view of the plug body  120 , as installed in the can  50 ; 
         FIG. 3   a  is a sectional view of an exemplary plug body  320 ; 
         FIG. 3   b  is a sectional view of the plug body  320 , as installed in the can  50 ; 
         FIG. 4  is a sectional view of an exemplary integrated plug body  420 ; 
         FIG. 5  is a sectional view of an exemplary integrated plug body  520  with an integrated extraction grip  595 ; 
         FIG. 6   a  is a sectional view of another exemplary plug body  620 ; 
         FIG. 6   b  is a sectional view of the plug body  620 , as installed in the can  50 ; 
         FIG. 7   a  is a perspective sectional view of an exemplary plug body  720  that features an inflated primary seal bladder  740 ; 
         FIG. 7   b  is a sectional view of the plug body  720  showing the primary seal bladder  740  in a deflated position; 
         FIG. 7   c  is a sectional view of the plug body  720  showing the primary seal bladder  740  in an inflated position as installed in the can  50 ; 
         FIG. 8   a  is a perspective view of an exemplary molded paint plug  800  that may be used with an alternatively shaped paint container  850 , also known as a bucket  850 ; 
         FIG. 8   b  is a perspective sectional view of an exemplary molded paint plug  800  that may be used with an alternatively shaped paint container  850  of  FIG. 8   a;    
         FIGS. 8   c  and  8   d  are, respectively, a top plan view and a sectional view of molded paint plug  800 ; 
         FIG. 9   a  is a front view of plug device  100 , showing the height reference disc  252 ; and detailed height markings on extraction strap  256 ; 
         FIGS. 9   b ,  9   d , and  9   e  are front sectional views and  FIG. 9   c  is a front view showing an exemplary process for positioning the plug in the can  50 . 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to the present exemplary embodiments, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. 
     A material storage device  100  according to the present invention will now be described in detail with reference to  FIGS. 1   a  to  1   d  and  2   a  to  2   e  of the accompanying drawings. The material storage device  100 , also known as a plug device  100 , may be used to plug a container of a material such as but not limited to paint. The plug device  100  may include a flexible plug body  120  and a plug handle section  150 . The plug device  100  may be positioned within a materials container such as a paint can  50  slightly above or touching the surface  54  of the paint  56  to seal the can after it has been opened and to prevent the paint surface  54  from forming a skin which could contaminate the remaining stored paint. The plug body  120  may be formed of a flexible material and may have a diameter that is the same as or slightly larger than the diameter of the interior wall  52  of the can  50 . 
     In operation, the plug body  120  is positioned at the top of the can  50  and pushed down along the interior wall  52  of the can  50  to the surface  54  of the paint  56 . The plug body  120  exerts resistance pressure against the interior wall  52  of the can  50 . As the plug body  120  is pushed down into the can  50  to the surface  54  of the paint, the resistance pressure causes the plug body  120  to scrape the paint on the interior surface  52  of the can down into the body of the paint  56  in the can, thus conserving paint and preventing any excess paint from forming a skin on the sides of the can which could contaminate the remaining stored paint. When the plug body  120  is positioned within the can  50  slightly above or touching the surface  54  of the paint  56 , it seals the can and removes the air between the paint surface and the bottom of the paint plug device surface, thus preventing the paint surface  54  from forming a skin which may contaminate the remaining stored paint and preventing evaporation which may cause the paint to become thick and unusable. 
     As shown in  FIG. 2   a , the plug body  120  has a body interior  230 , a primary seal  240 , a bottom reinforcement disc  210 , and a top reinforcement disc  215 . The primary seal  240  may be a circular flexible tube (a torus) with an outwardly facing curved surface and arranged to provide resistance pressure against the interior surface  52  of the can. In the embodiment shown in  FIG. 2   a , the primary seal  240  is a hollow torus, but it may be also formed of a compressible material that, when the seal is inserted into the can, will form the desired resistance pressure on the interior surface  52  of the can  50 . As shown in  FIG. 2   b , the tube may be segmented along a radial pattern to provide the plug body with flexibility to facilitate inserting the plug device  100  into the can. In further embodiments, the primary seal  240  may have an oblong cross section, not shown, to improve the desired resistance pressure when the plug body  120  is compressed within and fitted against the interior wall of the paint can  50 . 
     The body interior  230  may be a circular disc, formed of a medium to high density sponge material, with an outer edge onto which the primary seal  240  fits to form a larger disc having a diameter approximately the diameter of the interior wall  52  of the paint can  50 . In certain embodiments, the diameter of the plug body is slightly larger than the diameter of the interior wall of the can, in order to facilitate the seal. As shown in  FIG. 2   c , the body interior  230  may have an aperture  235  into which the extraction strap  256  may fit. 
     The plug body may also have a membrane  245  that encloses and attaches the body interior  230  and the primary seal  240 . The membrane material may be made of any suitable plastic or fabric material. The bottom reinforcement disc  210 , positioned below the body interior  230 , and the top reinforcement disc  215 , positioned above the body interior  230 , provide stability to the plug body  120 . The top reinforcement disc  215  may be formed of plastic or any suitable material, and may have an aperture sized to frictionally receive the extraction strap  256 . The bottom reinforcement disc  210  may be formed of plastic or any suitable material, and may be used to reinforce the plug body and constrain the end of the extraction strap  256 . 
     In addition, the plug body  120  may have a plug cover  290  that entirely covers the plug body to form a protective barrier between the paint, paint can sidewalls, and the paint plug external surfaces. The protective film may keep the paint material off of the paint plug device and prevent potential chemical reaction. The plug cover  290  may be held in place against the membrane  245  by placing its edges between the top reinforcement disc  215  and the membrane  245  and pressing the disc  215  against the membrane  245 , with friction operating against the extraction strap  256  to hold the reinforcement disc  215  in place against the membrane  245 . The plug cover  290  may also have an elasticized edge that fits over the plug body  120  to facilitate holding the cover in place. The plug cover  290  may be made from thin plastic film, such as those used in food storage bags, so that it is disposable after each use. The plug cover  290  may have suitable coatings applied, such as Teflon™ non-stick coating available from DuPont Co. of Wilmington, Del. to reduce paint adhesion to the paint plug and potential chemical reaction with the paint material. The choice of coatings may depend on the composition of the paint, for example, whether the paint is oil- or water-based. 
     The plug body  120  may optionally also have a lower seal  260  that is located below the primary seal  240  along the radial axis of the flexible plug body to cover the lower surface of the primary seal  240 . The lower seal  260 , as shown in  FIG. 2   d , may be disc shaped and formed from a flexible material such as rubber or vinyl, and may have the same shape as the primary seal  240 , such as round or oval. Additionally the lower seal  260  may have a slightly larger diameter than the primary seal  240 . The lower seal  260  may be used in conjunction with the primary seal  240  to improve the air seal. In addition, the lower seal  260  may cover the entire lower surface of the plug body and be used to help the plug body retain its shape over many uses and over a long period of time.  FIG. 2   d  shows the lower seal  260  before use.  FIG. 2   e  shows the plug body  120  in operation inside a can  50 , with the plug body  120  resting on the surface  54  of the paint  56 , the primary seal  240  compressed against the interior wall  52  of the can, the lower seal covering the surface  54  of the paint  56 , and the outer edge  262  of the lower seal  260  against the interior wall  52  and curled upward toward the primary seal  240 , thus sealing the paint  56  in the can  50 . As shown in  FIG. 2   e , the primary seal and the lower seal are configured to interact and to act independently to exert the resistance pressure against the interior wall of the container and to scrape the material from the interior wall of the container as the flexible plug body is being pushed down into the container. 
     An embodiment useful in positioning the plug within the can  50  is shown in  FIGS. 2   a  and  9   a - 9   e . As shown in  FIG. 2   a , the plug handle section  150  has a height reference disc  252  (also known as a depth gage disc), a strap handle  254 , and an extraction strap  256 . The depth gage disc  252 , which is shown as round, but may be any convenient shape, may be made of plastic or any suitable material, and may be used in conjunction with the extraction strap  256  as a reference to determine the depth to position the paint plug within the can  50 . The extraction strap  256  may be made of nylon or other rope type of material and may be used to extract the paint plug from the paint can  50 . It may also be used to stabilize the paint plug when inserting it into the paint can  50  and to provide frictional pressure against the top reinforcement disc  215  to hold it in place against the membrane  245 . 
     The extraction strap  256  may have also have depth markings  956   a - 956   h , shown in  FIG. 9   a , to identify how much paint is left in the can  50 .  FIG. 9   a  shows the plug device  100  in a de-compressed state, with depth markings  956   a - 956   h  on extraction strap  256  that may be coded with a fractional scale such as, respectively, 1/16, ⅛, ¼, ⅜, ½, ⅝, ¾, ⅞, to indicate approximately how much paint is remaining in the can. When the depth gage is set, the markers show approximately how much paint is remaining in the can. 
     In order to set the height of the depth gage disc  252 , as shown in  FIG. 9   b , a user of the paint plug device may insert a paint stirrer  950  or similar item into the paint can  50  until it touches the surface of the paint, then grip the top of the paint stirrer at the top of the paint can at position  950   a , thus establishing the depth to set the paint plug. The user may move the stirrer  950  to the plug device  100  and, as shown in  FIG. 9   c , reference this measurement by moving the depth gage disc  252  along the extraction strap  256  until the height from the bottom of the paint plug to the bottom of the depth gage disc  252  is the same as the measured depth  950   a . Once the depth gage disc  252  height is set, as shown in  FIG. 9   d , the user may reference the closest depth markings, shown in  FIG. 9   a , on extraction strap  256  to the depth gage disc  252  height. 
     When the paint plug device is inserted into the paint can, the user may put some tension on extraction strap  256  by holding strap handle  254  above the paint can  50  while lowering the paint plug into the can  50  with the other hand. The user may stop lowering the paint plug when the depth gage disc  252  is visually aligned to the top of the paint can  50 . The user may then drop the extraction strap  256  into the can  50 . For maximal sealing or medium to long term storage, the user may also replace the paint lid. The depth gage disc  252  is a convenience feature. A frequent user of the paint plug device may be able to judge the depth of the plug based on the change in resistance when pressing the plug against the paint surface and may not require the use of the depth gage disc  252  on a regular basis. 
     In other embodiments, a plug body  320  may have an upper seal to form additional sealing for improved air tight long term storage.  FIGS. 3   a  and  3   b  show an embodiment in which an upper seal  380  is positioned above the primary seal  340 . The upper seal  380  may be disc shaped and formed from a flexible material such as rubber or vinyl, and may have the same shape as the primary seal  340 , such as round or oval. Further, the upper seal  380  may cover the entire upper surface of the plug body and be used to help the plug body retain its shape over many uses and over a long period of time. Although it is shown in  FIG. 3   a  in a plug body that has a lower seal  360 , the upper seal  380  may be included on a plug body without a lower seal. In embodiments where it is included with the lower seal, the upper seal may be identical in shape and material to the lower seal. 
       FIG. 3   a  shows the upper seal  380  before use.  FIG. 3   b  shows the plug body  320  in operation inside a can  50 , with the plug body  320  resting on the surface  54  of the paint  56 , the primary seal  340  compressed against the interior wall  52  of the can, and the outer edge  382  of the upper seal  380  against the interior wall  52  and curled upward away from the primary seal  340 , thus providing additional sealing of the paint  56  in the can  50 . 
     In other embodiments, as shown in  FIG. 4 , an integrated plug body  420  may have a plug interior  430 , primary seal  440 , and lower seal  460  formed into a single molded component. This single molded piece may be made of rubber or any suitable material that will allow the plug to exert the desired resistance pressure against the interior walls of a paint can. 
     In further embodiments, as shown in  FIG. 5 , the plug body  520  may also have an integrated extraction grip  595  that may be used instead of the extraction strap to extract the paint plug from shallow, smaller cans. For example, a typical 8 ounce paint can has an approximate 2 inch diameter can opening and a 2½ inch can depth. The integrated extraction grip  595  may be gripped between the thumb and index finger to insert and extract the paint plug device scaled down for this type of application. 
       FIG. 6   a  shows an exemplary integrated plug body  620  that has a plug interior  630 , primary seal  640 , lower seal  660 , upper seal  680 , and extraction grip  695  formed into a single molded component.  FIG. 6   b  shows the plug body  620  in operation, with the plug body  620  resting on the surface  54  of the paint  56 , the primary seal  640  pressed against the interior wall  52  of the can. The outer edge  662  of the lower seal  660  is pressed against the interior wall  52  and curled upward away toward the primary seal  640 , and the outer edge  682  of the upper seal  680  is pressed against the interior wall  52  and curled upward away from the primary seal  640 , thus providing additional sealing of the paint  56  in the can  50 . 
     In another embodiment, as shown in  FIGS. 7   a - 7   c , a plug body  720  may be inflated to expand and compress against the interior wall  52  of the paint can. The plug body  720  may have a body interior  730  which may be made of a solid material such as recycled plastic and may have a concave surface on its outer diameter to keep the primary seal bladder  740  from slipping off the body when deflated and to provide stability to the primary seal bladder  740  when it is inflated. A seal inflation tube  756  may be attached to one end of the primary seal bladder  740  and at the other end to a tube seal, for example a conventional air valve (not shown) such as those used in a sport ball. The attachments may be outside of the body or inside, and the body may have a channel for the parts. A top reinforcement disc  715  and tube reinforcement disc  795  may be molded with the seal inflation tube  756  into a single unit. A bottom reinforcement disc  710  serves as a inflation tube plug and snaps into the bottom of the inflation tube  756  to hold it in place when placing and extracting the paint plug device. 
     In operation, the user may lower the plug with the deflated primary seal bladder using the seal inflation tube  756  until the plug is below the level of the top of the can. Air pumped through the air valve and tube  756  may partially inflate the primary seal bladder  740 . As the seal is being pushed down to the surface of the paint, the partially inflated primary seal bladder  740  pushes against the interior wall  52  of the paint in order to scrape the interior walls of the can. Once the plug body  720  is in place, air is pumped through the tube  756  to finish inflating the primary seal bladder  740 , thus completing a seal. Alternatively, in embodiments when scraping the interior walls of the container is not desired, the plug body  720  may be dropped to the surface of the paint. When the plug body is in place, the air is pumped through the tube  756  to inflate the primary seal bladder  740 , thus creating the seal. When the user wants to unseal the paint can, he releases the air valve, causing the air to exit the tube  756  and deflate the primary seal bladder  740 . The plug may then be extracted from the paint can by pulling the paint plug body  720  out of the can, for example by the tube  756 . 
     The paint plugs may be manufactured in a family of plug sizes to accommodate standard size paint containers, including, but not limited to 1 gallon, 1 quart and ½ pint sizes. In addition, the paint plugs may be manufactured in different shapes to accommodate the shape of the paint can or other material container. For example,  FIGS. 8   a  and  8   b  show a bucket  850  commonly used to hold paint during a painting job, with molded paint plug  800  installed as a seal. The bucket  850  has a non-circular interior wall  852 . 
       FIGS. 8   c  and  8   d  show more detail of the molded paint plug  800  that may be used to seal the bucket  850 . The molded paint plug  800  has a non-circular shape that conforms to the shape of the interior walls  852  of the bucket  850 . The molded paint plug  800  may be formed of a compressible material that, when the seal is inserted into the bucket  850 , forms the desired resistance pressure on the interior surface  852  of the bucket  850 . The molded paint plug  800  may have a grip  895 , a body interior  830 , a primary seal  840 , a bottom reinforcement disc  810 , and a top reinforcement disc  815 . 
     As with the embodiment shown in  FIGS. 2   a - 2   e , the primary seal  840  may be a flexible tube that is segmented, for example, along a radial pattern to provide plug body with flexibility to facilitate inserting the molded paint plug device  800  into the bucket  850 . The molded paint plug  800  may also have a lower seal  860  to improve the seal. 
     It may be seen that the embodiments of the devices and methods for sealing paint cans disclosed here may be used to greatly extend the shelf life of partially used paint within the original packaging. Many features are described that may be included in storage plug devices to accommodate the best price performance based on the type of paint being stored and how long it is intended to be stored. For example, if a paint is more expensive or if it is intended that the paint be stored for longer periods of time, the user may select an embodiment of the device that has additional upper and lower seals, to ensure increased sealing performance. The unique paint container wall scraping feature may be incorporated into a device to avoid paint contamination and maximize the amount of paint preserved for future use. In addition, the disclosed devices and methods reduce environmental stress on landfills because paint will last much longer and may be available for use for a longer period of time. The disclosed features reduce the cost associated with safe disposal of paint material, because less paint is wasted. 
     One of skill in the art will appreciate that the above-described stages may be embodied in several ways. Although the disclosed components have been described above as being separate units, one of ordinary skill in the art will recognize that functionalities provided by one or more units may be combined. As one of ordinary skill in the art will appreciate, one or more of units may be optional and may be omitted from implementations in certain embodiments. In addition, while the embodiments above have been described with reference to storing paint for reuse, it is to be understood that the devices and methods described herein are not limited to storing paints. Instead, the embodiments described herein may be used to store any materials, such as any liquids or solids, where there is a need to provide secure sealing for short or longer periods. 
     The foregoing descriptions have been presented for purposes of illustration. It is not exhaustive and does not limit the invention to the precise forms or embodiments disclosed. Modifications and adaptations of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the disclosed embodiments. For example, the described implementations may be implemented in a variety of materials, sizes and shapes, and be arranged differently than the figures illustrate. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.