Originally posted August 5, 2014 on
http://gadgetsblogofdoom.blogspot.com/
Chris and I have only done a few molds in fiberglass. This is the first proper one, done on a WED clay sculpture.
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After sculpting, Chris added a mold wall using .02″ x 4″ aluminum sheeting. I sheared it into strips and he inserted it into the clay. We wanted to try molding both halves at once to save time, instead of using a clay mold wall, fiberglassing one side, waiting for it to cure, then molding the other half.
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We sprayed three coats of PVA on each side. Then went over the aluminum with some sonite wax to he safe.
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While the PVA was drying, I ripped off a bunch of sections of 38-1/2″ 7-1/2oz fiberglass mat. This particular mat can only be used with polyester fiberglass resins. We prefer the mat over cloth for conformability to the sculpture.
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I pre dispensed some of the materials we would be using. I like even numbers, so I used 16oz cups of resin, as this took 5cc of MEKP.
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For the first two coats on each side, we used a 50/50 mix of bondo and resin, 16 oz of each, the activator for the bondo, and 5cc of MEKP.
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3 layers of mat on the main body and 5 on the mold wall later, and we have a mold.