Anybody with any significant experience with castalot? I'm trying to make reusable molds of a box shape, and the glass is always glued tight to the castalot after firing, making it more like cost-a -lot. I have kiln-washed the dickens out of it, prefired it according to directions, it's a plain box with no undercuts. I think the total lack of draft due to the steep sides is a problem, and I think the melting glass may be washing my kiln wash down those steep sides. Also, the contraction of the glass around the inside part of the box mold may be pinching it so tightly that I can't get the glass to release. The firing schedule is working- I get a glass box- but I have to break the mold to get it out. I contacted Michael Dupille, the inventer, and he suggested a different method of kiln washing and a different firing schedule, but it made no difference.
If anyone has any ideas for how to make this work better, or a different reusable mold material, please let me know! For now I'm trying a box with much shallower sides and a round shape instead of square, so maybe that will work, but I still think the pinching of the inside part of the mold will be an issue.