The first layer of rubber cured last night, so I went ahead today and worked on making the mother molds out of plaster. I covered the faces in plastic wrap, and then went ahead building what will eventually become the rubber mold out of ceramic clay over the rubber.
After covering all of the faces with an even layer of ceramic clay, I added shims, the pour hole, with more ceramic clay.
The first layer of plaster, which is very thin, is added to create one side of the mold with a bristle brush.
The second layer of plaster, which is very thick like cake frosting is applied using a butter knife.
After allowing the plaster to set on one side, I remove the clay shims. I brush Murphy’s oil soap on the shim area and then build the other side of the mother mold in the same way as I did the first side. Tomorrow I’ll open up the molds and pour my second layer of rubber.