The Ball molds do not have a flat base, because they are based on a perfect sphere. My work-around is to make a base "accessory". Put a smooth piece of aluminum foil in the bottom of the cold mold as a plaster release. Then pour in a little plaster until the round puddle of plaster is the diameter you want. (You can make a lot of these, as they don't survive many slump firings.) After the plaster sets REMOVE THE ALUMINUM FOIL and let the plaster completely dry. Then coat the flat surface with shelf primer and dry.
When you are ready to slump, put the plaster base accessory back in your mold.
The solution that other people use is to design exterior bases or feet, which stabilize and elevate the bowl.
Mary Kay Nitchie
Bullseye Glass Co.
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