AndreaB Posted March 9, 2016 Report Share Posted March 9, 2016 Good morning, Hope you can give me some advice. I've been making coiled bowls using bisque moulds by compressing clay in coils against the mould and then at leather hard adding coulor to the outside I no the crevices left by the coils. These bowls bisque perfectly but when glaze fired (stoneware clay by the way) to 1260 1/4 of them crack badly. Always at the bottom, inside and outside. I would really like to continue making these because they are really cool. One thought is to fire with an earthenware transparent glaze and to earthenware temp. Do you think this would work? Or can you give me another way to finish them? Link to comment Share on other sites More sharing options...
alabama Posted March 9, 2016 Report Share Posted March 9, 2016 Hey, You might try adding the colors or stains to vessels that are bisqued. Your bowl appears to be a variation of à style known as "corrugated" pottery, might want to google that and get more ideas. As for the cone 06 glazes on cone 6 clay bodies, you'll have to see if the two are compatible by testing and taking notes. There might be less guess work if you used earthenware clay and glazes together as well as stoneware clay and glazes. The cracking might be due to the clay body or using slips on your leatherhard surface. Are they cracks or coil fractures? Keep on testing! See ya, Alabama Link to comment Share on other sites More sharing options...
Denice Posted March 9, 2016 Report Share Posted March 9, 2016 I make a lot of coiled work, I don't use a mold like that but I make the bottom slightly thicker and make sure I do some nice even compression with a rib, just like you would a thrown pot. I couldn't tell by your photo where the cracks are either. Putting the wrong cone glaze on the clay could actually make the cracking worse, cause more stress. Denice Link to comment Share on other sites More sharing options...
Pres Posted March 9, 2016 Report Share Posted March 9, 2016 I really need to see the inside base where cracks are to be able to make any sort of assessment. Could you take a picture of inside and outside of pot? You may be having a shrinkage problem with the compressed clay on the sides putting too much pressure on the base. Or as others say, a glaze miss fit. best, Pres Link to comment Share on other sites More sharing options...
AndreaB Posted March 9, 2016 Author Report Share Posted March 9, 2016 Hi, thanks for the replies. The bottom of my last bowl and the inside. Hope these can give you insight. Link to comment Share on other sites More sharing options...
alabama Posted March 10, 2016 Report Share Posted March 10, 2016 Hey, Did you build coils on top of a clay paddie? If so, they're coil fractures... So, make a paddy with sides and build on those. Try alleviating seams, they take time to smooth/blend and are the weakest point! Keep on trying different methods. I don't slip and score coils, I over lap them 1/4 to 1/2 of the way then blend them together. Good luck, Alabama Link to comment Share on other sites More sharing options...
bciskepottery Posted March 10, 2016 Report Share Posted March 10, 2016 When coil building, I often use a clay flower pot saucer as the bottom mold. A round slab is fitted/formed against the bottom and sides. Then I build up. That eliminates a join on the very bottom. Link to comment Share on other sites More sharing options...
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