Makers Meet To Make A Mold, Second Part

The next morning I demolded the first half of the silicon rubber for MattC’s hammer head.  I cleaned all the surfaces of any residual clay from the embedding.  I spread a parting agent (petroleum jelly) over all of the silicon mold surfaces and reassembled the first half mold including the original wooden master pattern and the attendant elements.  [Sorry for the blurry pic — note to self, do not drop your camera on the concrete floor, it don’t work so good after that)

Reconstructing an identical plastic brick dam, I repeated the mixing and Matt poured the liquid silicon molding material and we let it sit again overnight to harden.

Once the entire rubber mold was separated and cleaned it was ready to go for making wax models for lost wax casting.  I did cast one wax pattern and saw that I needed to expand the sprues a little with a scalpel.  Had I used a larger piece of wire or tubing there would not have been a problem.

Just for the heck of it I walked him through the process for casting pewter directly into the mold, which requires depositing powdered graphite on all the cast surfaces to reduce the surface tension of the molten metal.  I mimicked the process with wax and he got a kick out of the metallic-looking wax pattern.

At this point I turned the mold over to Matt to proceed with the enterprise from his end.  My work was done.

Except for the second hammer head.  Stay tuned.