Breaking Out the Casting

I let the investment cool overnight. Then I began breaking it open.

After the investment material has been broken away, this is what I have left. Now comes the crucial moment when we see if we have a good casting or not. (Sometimes they are not not.)

The loose plaster has been cleaned off. The casting is a success.

Several explanations are in order here.

  • First: What is all that other stuff attached to China Doll? There is a lot more of that other stuff than there is of her.

  • Well, the molten metal meeds a way to get to the casting. The air that is inside the investment needs a way to get out, and the melted wax needs a way to get out as well. So I welded wax tubes to her that allow for all of this to happen, and I made a funnel shaped cup to pour the metal into. Notice that I attached the center tube to her bare belly, which is perfectly smooth. That way I can remove the remaining traces after I cut the tube off without having to cut any complicated texture into the casting with a chisel.

    The second question is:
  • What are those thin rods sticking out of the casting?

  • Well, remember the casting is hollow; the wax is only three-sixteenths of an inch thick. What I did was to pour some investment mix into the hollow wax before I welded on the flat wax plate that becomes the base. (Wax is welded with a hot knife.) All well and fine, except for the fact that when the wax is melted out, that core will be unsupported; it must be held in place by something. I inserted those thin steel pins to do this. There are a few more near her shoulders. This presents a problem of course: the steel pins must be driven out of the casting leaving holes that have to be patched.

    I have cut off most of the now superfluous stuff, driven out the steel pinns, and patched the holes by brazing in bronze plugs.

    Next is to cut off the bronze plugs, finish removing everything that is not China Doll, and clean up the surface of her body and skirt with a sharp chisel.

    And after some polishing and the application of a brown patina, we have a finished casting.

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