Thursday, August 26, 2010

Unusual shapes

There was no question that I would need to cast Elsie's tail separately. What I hoped was that once I cut it free from the sculpture, I could find some kind of angle that would simplify the shape for mold-making. As it turns out, there wasn't a magic angle. It was a shape that didn't work well from any angle, and I was stumped about where to draw the mold lines.

I finally decided that I'd clay up one side, pour the first side piece and figure out what to do from there. I had high hopes that the planes would suddenly make sense once one was covered, but I also knew that I had rapidly degenerating rubber components. Polyurethane prepolymer (rubber Part A) degrades after it has been exposed to air, so I needed to use what I had left quickly. Experimenting seemed like a good idea.

The process did work, though there really wasn't a simple answer. The strands of the tail move in too many directions for anything but a fairly complex mold. Right now I think it will be a five piece mold, though the area that fits inside the bend may work better broken from the rest of that piece. That's five, possibly six, pieces and we haven't made it to the body yet!

Meanwhile Oliver's two production molds are about half-dry. I am dying to test them.

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