Yes, we bake some of the molds in out trusty kitchen stove oven. Three to six hours at 200 degrees depending on the thickness of the mold piece. This one was baked for six hours. (Note: the door is open for the picture. I keep it closed during the heating process.)
It fills the house with the smell of oranges, the product of the 3M Citrus Based Cleaner baking out of the mold along with quite a bit of water. In the six hours, the mold will lose about one-fifth of its weight in lost water.
Now, we're done with the plaster, and its on to the Neoprene
Here's a torso mold filled with the Chicago 501 Industrial Latex (Neoprene). The two plaster half-molds are first dusted with talcum powder (to aid in release of the Neoprene) then lashed together with the bungee cords. Then some of the same plasticene we carve the heads with is used to seal the seams between the two halves. I place the mold in a containment vessel large enough to contain all of the neoprene in case of a leak.This torso mold took just slightly less than a gallon of liquid neoprene to fill., and I'll get back about 3/4 of a gallon of it to use again.
The water in the neoprene gets absorbed into the plaster, leaving a thin shell (like the coating on an M&M candy). The process takes about four hours to build up a layer about 1/8" thick. During this time you have to keep topping off the neoprene to the top of the mold. Once the four hours pass, the remaining liquid is syphoned or poured out and kept for reuse. The mold is left to set overnight (Eight hours, or so) and is then ready for opening.
Neoprene currently costs $50.00 per gallon delivered to our door. One gallon will pour three to four torsos OR four to five heads for 30" scale puppets.
After the four hours, the remaining liquid neoprene is dumped or syphoned out of the mold, and can be reused in the next mold. You just have to have enough on hand to be able to fill each mold in succession, so the big ones usually get done first.
I leave the mold to dry overnight, before attempting to open it.
This lets the neoprene get hard enough to hold together when the two mold halves are pried apart, but not so long that small undercuts won't release the neoprene.
Success!!! Here's the pair of shoes ready to remove from the second half of the mold. I usually blow a bit of talc in the top before opening the mold in case the neoprene touches itself in the removal process. It won't stick together that way. The finished pieces are really soft at this point, and could be rolled up into a ball with little or no trouble.
One of our drying racks. Here are two shoes and a torso drying in front of our air conditioner.
The torso is attached to a spinner which slowly
rotates it for even drying.
I'll let them dry for three hours before attempting to
work on them further.