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This is possible because Polar Ice, the casting version, behaves like rubber after draining. The rims can be peeled away from the mold and the piece can be completely collapsed to forcibly peel it out of the mold. They could then be opened and dried. To add more insult to the wonky shape large pieces can be broken away at leather-hard stage and then reattached using the slip as glue - the piece will still dry normally! The 1% Veegum is solely responsible for all of this, without it the New Zealand kaolin based slip would be too fragile to even cast this.
This test mold is thin-walled yet I can cast three thick-walled mugs in three hours. This clay is L2596G, a buff burning cone 10 stoneware - the mug on the lower right has been fired to cone 10 oxidation. Achieving 4-5mm thick walls is not a problem if the casting slip employs a large particle kaolin intended for this purpose (e.g. Opticast). The flared lip works as expected, keeping the rim nice and round. No cracks have appeared at handle joins, even for pieces left in the mold overnight. The mold halves mate with each other very well and the seam is easy to remove. The seam on the base is an issue - I have to be careful to line up the halves well before clamping the mold strap - this is a warning for accuracy during the mold production stage. And the possible motive for a three-piece mold.
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