Monday, December 3, 2012
08 Joint Design Nº 26
I rolled out some Roma Plastilina into a slab about 12mm thick. I pressed the slab into the cavity of the first half of the the plaster mold. Then I used a kitchen knife to cut off the excess clay. Click on any image to enlarge it.
After cutting off the excess clay with the kitchen knife, I rolled out a coil of clay, cut it in half, and added it as a spare.
This is the another view of the spare. I also cut four registration keys.
Next I applied a parting agent made from a 50/50 soap/water solution to all surfaces.
After I applied three coats of parting agent, I placed the coddles around the plaster and clamped them together.
I mixed the water and plaster in a 2:3 ratio, let it slack, then poured it into the mold cavity. I turned on the mold table vibrator when pouring this half.
I let the plaster set up for an hour and a half, then I removed the coddles.
In this view, you can see the top of the clay spare.
This mold parted very easily, with a gentle pulling apart, using my hands.
I used my paring knife to trim the mold.
This is the mold, banded together. I am going to let it set up overnight before soaking it in water. I will soak it in water in order to cast carving wax into it. I will cast four carving wax ball halves and weld them together to make the full balls.
I am not going to bevel the edges yet. I may use one half of this mold to make a full sphere mold. It all depends on how much the carving wax shrinks with this mold.
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