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.
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.
We sprayed three coats of PVA on each side. Then went over the aluminum with some sonite wax to he safe.
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.
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.
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.
3 layers of mat on the main body and 5 on the mold wall later, and we have a mold.