Preparing Rubbermold for Casting

We are using a silicone rubber with a plaster mother mold shell. The mold is completely clean and dry.

Prior to casting a resin or any cast, applying a light coating of Universal mold release or a light brushing of a paste wax will preserve the rubber for many castings.

Epoxy/Resin Lay-Up

The resin is measured and mixed and applied with a brush. It is important to get into all the detailed areas (ears, undercuts etc).

After the first coat gets tacky another thicker coat can be applied. Generally 3-4 coats are sufficient to build a uniformed thickness of 1/4". Fiberglass matting was added after the second application. This will add strength to the casting.

Opening the Mold Sections

Some molds have a number of sections. In this case prior to casting, try and close as many sections as possible before casting. I had two mold sections a front and a back. I built up a cast in each mold as explained above. Then applied a thickened amount of resin to the edge of the hollow cast in each mold.

Before the resin sets put the mold sections together and close the mold. After the cast has fully cured the mold can be opened and the resin cast removed from the mold. Always make sure the rubber is properly placed back in the mold and all the keys are secured in the mother mold.

As you can see there is some work ahead cleaning of the resin flashing from around the seamline and joining the various parts to the sculpture.

Next Step:

Assembly of Parts and Chasing the Zappa Resin Cast