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In that photo is an excellent example of his skill at mold-making. Rope secures a plaster of paris mold which is actually only the outside mold of two molds. The inner mold is made of latex rubber, which is too floppy to hold its shape so it must be carefully splinted with a second mold of plaster for the duration of the hardening of the cast, in this case a foam cast which has spilled out of the pour spout on the left end as it should. The plaster mold itself is a fairly complex one because it consists of more than two halves, the basic number of parts of a multi-part mold.
His ability to make molds, some of them 9 feet long, out of fiber glass, came from innate skills which were refined first in creamics and then in preparation. The first mold-making that I remember took place out on the little 2 acre farm south of Vernal when I was around 8 - 9. I watched the process and wanted to make one of my own. In a rare fit of generosity (which I suspect was named “Marie”) he agreed to help me make one.
I had to pick out something to make a mold of and he was very particular. I personally wanted to make a mold of a dog or a cat, something ‘real’ that I could play with. After some intelligent discussions, I ‘decided’ that what I ‘really’ wanted to do was make a mold of a small glass bowl. It was about 4 inches across and was about an inch tall, and was decorated with small depressions around the outside surface.
The mold was the most basic of all, i.e. a “one piece mold’. Dad helped me make a sort of box in the middle of which I placed the dish - after I had carefully painted it with Tincture of Green Soap - what a great name, Tincture. Never heard it otherwise but it sounded important. The sides of this box were made out of thick layers of plasticene, the clay that he used for everything that needed special shapes. The purpose of the clay was to be a buffer around the subject bowl to hold the plaster of paris as long as it was liquid.
After the Tincture of Green Soap was dried, the bowl was placed open side down in the middle of this little plasticene corral affair. Then dad mixed -I sort of helped but not much because it is a ticklish job to do right - the plaster of paris. We poured it over the bowl until it was probably half an inch deeper than the depth of the bowl.
After the plaster was hardened, we separated the bowl from the plaster with some difficulty. I think that the only reason we were able to separate them was because dad had a compressor so could use compresed air to blow into the crack between the bowl and the plaster, thereby forcing it out. A two-part mold wouldn’t have had this problem, but dad was always in a hurry to get back to “’his” work which was more important.
The plaster mold which had a depression shaped precisely like the little bowl had to dry completely which took a long time. When it was dry, we filled the space with slip, i.e. liquified clay that pours like syrup. Then magic happened. As we watched, the outer edge of the slip changed from shiny to something else. That was proper because the plaster was absorbing the water from the outer surface of slip which was in contact with the plaster. Over a short period of time, a ‘layer’ of the clay developed into a tough leathery skin. When it was a quarter of an inch thick, we inverted the mold over a large-mouth vessel to collect the slip because it can be used again.
After the slip had stopped running, we turned the mold right side up and let it sit half an hour or so, trying every so often with the tip of a knife blade to see if we could pry the newly formed bowl out of the mold without tearing it. The time came when the clay had dried enough that we could actually pry it out of the mold. At that point we trimmed off the rough edges and set the thing aside to dry for a day or two. After it was dry, we firee it to become “bisque”, then we glazed and refired it.
Here’s an example of a small three-piece beeehive mold and here is the Antrodemus skull mold.
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