Patbaba Posted April 24, 2010 Report Share Posted April 24, 2010 I recently bought a Hydro Bat plaster slump mold for making a salad bowl. It is 12 1/2 in Diameter and 6 inches deep. I put the mold on the wheel and draped the slab over. I then ribbed the bowl shape with a little water and a plastic rib and trimmed the bottom up about 1/2 inch. Then I rolled a coil and "threw a 4" foot on the bowl. Finally I smacked the bowl with a wooden spoon while turning on the wheel to create a texture on the outside of the bowl. I have done this with successfully with a 14" x 4" deep mold. I covered the bowl while on the mold fairly loosely with plastic and returned the next morning. The bowl was still quite firmly stuck on the mold. I took a wooden knife and cut along the rim of the bowl to be sure it wasn't stuck due to "throwing" it while on the mold. I covered again and came back that evening to begin gently loosening around the rim. I noticed a long 5" vertical crack and little cracks around the rim. Because the slump mold is pretty steep, the angle at the bottom of the bowl is nearly 90 degrees leaving no place for the shrinking clay to get relief. Since this form was purchased by a reputable supplier I assume someone must have had success in getting the bowl off the bat. Any ideas? Thanks, Pat Link to comment Share on other sites More sharing options...
Patbaba Posted April 27, 2010 Author Report Share Posted April 27, 2010 I recently bought a Hydro Bat plaster slump mold for making a salad bowl. It is 12 1/2 in Diameter and 6 inches deep. I put the mold on the wheel and draped the slab over. I then ribbed the bowl shape with a little water and a plastic rib and trimmed the bottom up about 1/2 inch. Then I rolled a coil and "threw a 4" foot on the bowl. Finally I smacked the bowl with a wooden spoon while turning on the wheel to create a texture on the outside of the bowl. I have done this with successfully with a 14" x 4" deep mold. I covered the bowl while on the mold fairly loosely with plastic and returned the next morning. The bowl was still quite firmly stuck on the mold. I took a wooden knife and cut along the rim of the bowl to be sure it wasn't stuck due to "throwing" it while on the mold. I covered again and came back that evening to begin gently loosening around the rim. I noticed a long 5" vertical crack and little cracks around the rim. Because the slump mold is pretty steep, the angle at the bottom of the bowl is nearly 90 degrees leaving no place for the shrinking clay to get relief. Since this form was purchased by a reputable supplier I assume someone must have had success in getting the bowl off the bat. Any ideas? Thanks, Pat Link to comment Share on other sites More sharing options...
Patbaba Posted April 27, 2010 Author Report Share Posted April 27, 2010 In case anyone wants an update, I solved the problem above. We noticed that the mold actually curved under slightly at the bottom potentially making it impossible for the clay slab to release from the mold. I undercut the slab an inch higher so it wasn't under the slight lip. This time I took it home where I could "babysit" the drying process properly. So far so good. I did not, however, smack the outer surface with the spoon for texture as I had before. This week I'm going to try the higher undercut and texturing with the spoon. I work at a community art center and one problem is monitoring the drying process. Alas, the companionship of the community outweighs the occassional lost pot. Pat Link to comment Share on other sites More sharing options...
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