couple of people asked me how the castings came out from molding a rubber fish. worked really well so I will share what I did.
ok, so here is the low down on casting a rubbber master copy for a production silicone mold. the first half of the process is no real news, takeing what I learned from tutorials from this fourum (i.e. Mr. Knuths tutorial on casting a crappie.
).
1. Fish is layed into a bed of high fiber. Fish is essentially posed in an almost flat position. the flat pose gives you the option of alternate posings in the production mold assembly.
2. in a mixxing cup, mix 1 part polyester resin and 1 part bondo (both pre mixed with their catylists). pour over entire fish with a light brushing over the surface to remove bubbles.
3. after initial coat has set up, repeat process with 1 part bondo/3 parts resin. sandwhich in fiberglass matting.
4. demold the fish, clean the mold thoroughly, and let dry.
5. drill a hole in the upper most portion of the mold (ie, tip of bottom mandible) BE CAREFUL NOT TO BREAK THE MOLD!... or you will be super glueing.
6. brush on a thin coat of your liquid rubber of choice over entire surface of fish and fins in the mold and close the mold up. hotglue or tape up the seams making sure there can be no leakage. I use CHROME tape.
7. while standing the fish mold on its tail (head up). pour in liquid rubber with a shore of 20A - 30A (mold max or vitaflex). depends on how flexable you want your fish to be. let stand over night.
from here you can remold the fish in a number of different poses useing the original process.. or, for something quicker....
8. If you want to mold the fish in the exact position as the initial cast, just demold one side of the bondo/resin shell. the other half is to stay in place and used for the dams needed to separate the production mold. otherwise repose in high fiber as if the rubber fish was the real thing.
9. hotglue a border all the way around the fish to catch the material. apply the propper releases and use a brushable silicone (I will try mold max stroke next go around) . feather in a few pieces of material/fiber to allow the moter mold to "grab" ahold of the rubber.
10. once this silicone has dried, a bondo/resin mother mold can be applied over the surface of the rubber. make sure to work materials into the fibers imbeedied in the surface of the rubber for a good bond between the two.
11. remove the other half of the origial bondo/resin shell or if repositioned, high fiber, and repeat the process from step 8 through 9.
12. demold the rubber casting and re-assemble back in the original bondo/resin mold for storage. now you can make a ton of casts from the new mold without any loss of detail from the actual fish.
here are a few pics
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