Saturday, June 20, 2015
09 Plaster Production Molds Nº 215
I carve registration keys with a teaspoon tool with a flattened spoon that has an aluminum gutter nail duct-taped to it. Just twist it back and forth while pressing down on the nail head until the key is deep enough.
I apply a 50/50 solution water and liquid soap as a parting agent. I have the solution mixed up in a jar. I take out a little bit at a time and put it in a small bowl when I soap the mold. This mold was soaped three times.
The coddles are placed around the first mold piece with the oil clay build-up in place. I attach them to the mold table with oil clay coils pressed around the bottom of the coddles, and up the corner seams to seal it. I use C or G clamps to secure the coddles to each other.
I weigh the water and plaster to have a ratio of 2 to 3. Today I weighed out 4 pounds of water and 6 pounds of plaster. This was based on how much extra plaster I had from pouring the first half of the mold. I always add plaster to the water, sifting it through my fingers quickly and evenly. I let the mix slack until the plaster has absorbed all the water. Then I push the island of plaster down and mix it with my hand and fingers, squishing out all the lumps, until it is creamy smooth. When I can draw an S on the surface of the mix with my finger, and just see it afterwards, the plaster is ready to pour. I quickly wash my hands in the water bucket, dry them off on a rag, then turn the mold table vibrator ON. I pour the plaster into the coddles in an even stream. Then I turn the mold table vibrator OFF.
I empty any excess plaster into the lined trash bin. I wash my hands, tools, and mixing bowls in the bucket of water. Never put plaster (dry, set, or wet) down the drain pipes.
It is a good idea to let the plaster set up for at least an hour. It goes through several stages during setup, including an exothermic reaction which can get quite warm. Yay !!! Another mold piece done.
Links To BJD Tutorials
This work is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License.