Sunday, October 10, 2010
Build-ups For Back-ups
I am still working on making cardboard build-ups for the wax parts that I'm going to be making plaster rough shell molds of. I'm using cereal box cardboard for the build-ups. I put the part down on the cardboard and trace around it with a pencil. Then I cut out the shape, inside the line. It usually needs some more trimming, which I do with scissors, after trying to put the cardboard around the part. Once the build-up fits over the part easily, I start applying balls of wax to the backside, while positioning the cardboard along the parting line. It is really easy to find the parting line because it is usually the line made by the edge of the cardboard armature.
I like to make a cardboard build-up for a rough shell mold because it doesn't take as long to make one as it does to make a clay build-up around the part. I can use clay to make things like the spare, and other pieces, like for hip sockets, and shoulder sockets.
I am making these rough shell molds as backups, before I start doing surgery on all the parts to change them to conform to my new working drawing. The idea is that I can always return to this point in the doll making process, for whatever reason. Another reason I am making these molds is so that I will have some carving wax doll parts to play with, for testing joints, for adding and subtracting carving wax, and for testing ways to finish parts. The carving wax can always be reused by putting it back in the wax pot when I am finished with it. I haven't stopped to take any photos, yet, but I'll try to remember photos before I mix the plaster. They are looking very similar to the photos in this post from July.
In Chaney & Skee they show how to make a fancy plaster build-up from a thin sheet of plaster that is cast on a piece of plate glass. I have a nice piece of plate glass in my studio that is 1/2 inch thick, and 24x24 inches square. Alternatively, a piece of plywood counter top covered with Formica works good.
Pliver is very thin lamb's hide used to suede ball joints.
Here is a source for pliver on EBay.
Twigling recommends pliver for sueding the joints of BJDs in her Zen booklet.
Dan Perez Studios has good mold making tutorials. This link shows a clay build-up being made. There are also pictures of a hand mold being made, once again, in a clay build-up. Note that the tutorial shown is for making a silicone rubber mold, not a plaster mold. Plaster is a rigid mold making material. Silicone rubber is a flexible mold making material. A plaster mold cannot have undercuts, nor does it need all those little registration keys, amongst other considerations.
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