Abstract:
A soft plastic fishing lures may be made to float by incorporating air bubbles therein by methods and in molds that draw air from inside the molds in which the lures are cast.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to fishing lures, and more particularly, to soft bodied fishing lures that float, and to molds for and methods of making floating fishing lures. Floating soft bodied fishing lures have been made by adding to plastic formulations chemicals that produce gas bubbles in the cured plastic. The resulting lures were tough and not natural feeling, and the colors were opaque and difficult to control. Also, air has been incorporated by agitating melted plastic before a lure body is formed, but the size, location and distribution of air bubbles in the lure can not be controlled. Selected areas of prior lures could not be made devoid of bubbles. 
     OBJECTIVES OF THE INVENTION 
     Accordingly, it is an object of this invention to provide improved fishing lures and improved molds for and methods of making the lures. 
     Another object is to encapsulate air bubbles in fishing lure bodies without diminishing the transparency or translucency of the plastic from which the lures are made. 
     An additional object is to provide floating fishing lures that have craters on their exterior surface for holding scenting and taste imparting agents. 
     Another object is to control the number and location of air bubbles in fishing lures. 
     An additional object is to provide fishing lures that have air bubbles in preselected locations but have no bubbles in other preselected areas. 
     A further object is to place differently sized air bubbles in different selected locations in fishing lures. 
     Another object is to provide methods and molds that can locate air bubbles only in predetermined portions of fishing lures and prevent the bubbles from forming in other predetermined portions of the lures. 
     A further object is to provide floating plastic fishing lures that are durable, economical, highly attractive to fish, easy to use, and which do not possess defects found in similar prior art lures. 
     A further object is to control the size of air bubbles in plastic fishing lures. 
     A further object is to provide improved methods for making the fishing lures described herein. 
     Another object is to provide porous molds that breathe and control the size and location of air bubbles in plastic fishing lures. 
     Other objects and advantages of the fishing lures and manufacturing methods and molds incorporating this invention will be found in the specification and claims and the scope of the invention will be set forth in the claims. 
    
    
     DESCRIPTION OF THE DRAWING 
     FIG. 1 is a schematic top plan view of a fishing lure in accord with this invention. 
     FIG. 2 is a schematic partially cross sectional side view of a step in a process of making fishing lures in accord with this invention. 
     FIG. 3 is a schematic partially cross sectional side view of another step in the process of making fishing lures. 
     FIG. 4 is a schematic partially cross sectional side view of another step in the process of making fishing lures. 
     FIG. 5 is a schematic partially cross sectional side view of another step in the process of making fishing lures. 
     FIG. 6 is a schematic partially cross sectional side view of another step in the process of making fishing lures. 
     FIG. 7 is a schematic partially cross sectional side view of another step in the process of making fishing lures. 
     FIG. 8 is a schematic partially cross sectional side view of another step in the process of making fishing lures. 
     FIG. 9 is an enlarged cross sectional view taken generally along the line  9 — 9  in FIG.  8 . 
     FIG. 10 is a schematic partially cross sectional side view of another step in the process of making fishing lures. 
     FIG. 11 is a schematic partially cross sectional side view of a step in another process of making fishing lures in accord with this invention. 
     FIG. 12 is a schematic partially cross sectional side view of a step in another process of making fishing lures in accord with this invention. 
    
    
     DESCRIPTION OF THE INVENTION 
     The drawing shows a soft natural feeling , flexible fishing lure  1  in accord with this invention. A number of spaced visible air bubbles  2  are encapsulated inside of the body of the lure. The air bubbles adjacent one end  3  of the lure may be a different size from the bubbles adjacent the other end  4 . The upper surface  5  of the lure  1  may be essentially smooth and uninterrupted except that it may have randomly located pock marks or craters  6 . A portion  7  of the lure at the end  3  may be solid and bubble free to facilitate impaling the lure on a hook or for connecting the lure to other rigging. 
     Preferably, the lure  1  is made from a soft, flexible, natural feeling synthetic plastic material, such as a thermoplastic plastisol resin formulation that includes polyvinyl chloride plasticized with esters of phathalate. It is also preferred that the lure body be colored and translucent or transparent so that the bubbles  2  are visible. However, natural and synthetic rubbers may be used for the body of lure  1  as may thermosetting synthetic plastics. 
     The lure  1  may be made by the process illustrated in FIGS. 2-10. In FIG. 2 a model  10  of the lure  1  has been placed on the bottom of a container  11 . The model  10  may be shaped to resemble any aquatic or land creature upon which fish feed, or it may have an unnatural shape that provokes fish to strike. A supply  12  of uncured ceramic slip  14  is poured into the container embedding the model  10  in the slip. The slip  14  is allowed to cure around the model  10  and thus to produce the mold  15 , as shown in FIG.  3 . The cured slip must be porous and must have air entrained therein so that the body of mold  15  will be a breathing porous mass of pores and interstices that permit the passage of air there through. Mackie&#39;s premixed ceramic slip from Mackie Newton Ceramics, Inc. has been used to practice this invention. 
     After the slip  14  has cured, the mold  15  is removed from the container  11 , and the model  10  is removed from the body of the mold, as shown in FIG.  4 . The space previously occupied by the model  10  defines the mold cavity  16  in which the lure  1  will be cast. The cavity  16  must be sealed by completely coating the cavity with a ceramic glaze  17  that is impervious to air. The glaze  17  may be applied by painting in on the surfaces of the cavity with a brush  19 . After the glaze  17  has cured, it must seal the porous body of the mold  15  from contact with hot molten material from which the lure  1  will be cast. Duncan&#39;s 1N1001 clear Infinity premixed ceramic glaze has been used to practice this invention. 
     The seal produced by the cured glaze  17  must be broken by openings  19  that penetrate into the porous mold body. The openings  19  may be holes or scratches of any shape. As shown in FIG. 6, the cured glaze  17  may be punctured with a sharp tool  20 , such as an awl or a needle, to produce circular holes  21  that penetrate through the glaze into the porous ceramic of the mold body. The tool  20  also may be used to scratch through the cured glaze. Alternatively, the holes  21  may be drilled through the glaze and into the mold body. This exposes the interior of the mold to the atmosphere when the cavity  16  is empty. It has been discovered that when the holes  21  are sized as disclosed herein, the air entrained in the porous mass of the mold  15  can be released into the body of the lure  1  during the casting process, and the molten plastic will not clog the holes  21 . The holes  21  should be no larger than about 0.050 inches and no smaller than about 0.0001 inches. 
     FIG. 7 shows a supply  22  of molten plastic resin  23  that has been heated to a preferred range of about 280 to about 400 degrees Fahrenheit being poured into the cavity  16 . The cavity is essentially filled, as shown in FIGS. 8 and 9, and the resin is permitted to cure as it cools to about the ambient or room temperature. Air from the interior of the porous mold will rise into the molten plastic  23  and form the bubbles  2  therein. The air from inside the mold is pushed upwardly because the hot plastic in the above temperature range heats the mold and thus expands the entrained air. As the plastic cools down from this temperature range it has sufficient surface tension to prevent the liquid plastic from entering the holes  21 . When the resin remains in the cavity  16  for up to about fifteen minutes until it cures at ambient or room temperature, bubbles  2  will be trapped or encapsulated within the body of the lure  1 . 
     Some of the bubbles  2  will move upwardly through the liquid resin while it is curing until they burst through the upper surface  5 . These eruptions will result in the craters  6  in the upper surface  5  of the lure. These craters  6  may be used by fishermen to hold scent or taste material on the lure  1 . When the resin has finished curing, the lure  1  is removed from the cavity  16 , as shown in FIG.  10 . Since the porous ceramic interior of the mold  15  is now exposed to the atmosphere, ambient air enters the interior of the mold through the holes  21  and recharges the mold for creating bubbles  2  when the next lure  1  is cast. 
     The location of the bubbles  2  in the lure  1  can be controlled by predetermining the location of the holes  21  in the mold cavity  16 . Holes may be selected within the preferred size range of about 0.0001 to about 0.050 inches to determine and control the size of the bubbles  2 . For example, as shown in FIG. 8, the holes  21  adjacent the end  24  of the mold are larger than the holes  21  adjacent the opposite end  25 . This results in the bubbles  2  at the corresponding end  3  of the lure body being a first general size that is larger than the second general size of the bubbles at the opposite end  4  of the lure. Similarly, FIG. 9 shows that relatively smaller holes  21  at the center of the mold result in smaller bubbles  2  at the center of the lure body than those produced by the larger holes  21  adjacent the outer edges of the mold. By thus controlling the size and location of the bubbles  2  within the body of lure  1 , its buoyancy can be controlled. For example, one end or portion of the lure  1  may be made to float above a different end or portion of the lure. The action of the lure  1  as it is retrieved can also be influenced by controlling the size and location of the bubbles  2 . There are no holes at the terminal end  24  so that there will not be any bubbles where the end  3  of the lure terminates. This makes the bubble-free end  3  stronger and better able to stay on a hook and resist the shearing forces that occur when a fish strikes the lure or when the lure snags. 
     FIG. 11 shows another embodiment of the invention that is identical to the above embodiment, except for the steps employed to create the cavity  16  in the mold  15 . First a supply  12  of the uncured ceramic slip  14  is poured into the empty container  11  until the container is essentially filled. Then the model  10  of the lure is embedded by pressing it into the upper surface of the uncured slip  14 . After the slip has cured, the model  10  is removed, and the remaining steps in the creation of the mold and the casting of the lure  1  are identical to those described above. 
     FIG. 12 shows another embodiment of the invention that is identical to the above embodiments, except for the steps employed to create the cavity  16  in the mold  15 . The slip  14  is poured into a container and allowed to cure as shown and described with references to FIG. 11 without embedding a model of the lure in the uncured slip. After the slip has cured, the body of the mold  15  is removed from the container and tools, such as a rotating burr  26  and/or hand chisels, are used to carve the cavity  16  in which the lure will be cast. The remaining steps in the creation of the mold and the casting of the lure  1  are identical to those described above. 
     While the present invention has been described with reference to particular embodiments and method steps, it is not intended to illustrate or describe all of the equivalent forms or ramifications thereof. For example, the lure body may be shaped to resemble any aquatic or land creature upon which fish feed, or the lure body may have any unnatural shape that provokes fish to strike. Also, the words used are words of description rather than limitation, and various changes may be made without departing from the spirit or scope of the invention disclosed herein. It is intended that the appended claims cover all such changes as fall within the true spirit and scope of the invention.