Cracking in pieces after glazing - Electric Mid&Hi Fired Ceramics2024-03-29T13:10:41Zhttps://cone6pots.ning.com/forum/topics/cracking-in-pieces-after-glazing?commentId=2103784%3AComment%3A115823&x=1&feed=yes&xn_auth=noMixing clays with two differe…tag:cone6pots.ning.com,2014-11-12:2103784:Comment:1158232014-11-12T06:35:39.979ZNorm Stuarthttps://cone6pots.ning.com/profile/NormStuart
<p>Mixing clays with two different COE or shrink ratios can certainly build up enough stress in the kiln to develop cracks. Sometimes even before firing this stress can develop cracks.</p>
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<p>I think you found your problem.</p>
<p>Mixing clays with two different COE or shrink ratios can certainly build up enough stress in the kiln to develop cracks. Sometimes even before firing this stress can develop cracks.</p>
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<p>I think you found your problem.</p> Norm,
Thanks for responding. …tag:cone6pots.ning.com,2014-11-12:2103784:Comment:1159522014-11-12T06:04:00.391ZBonnie Hornsbyhttps://cone6pots.ning.com/profile/BonnieHornsby
<p>Norm,</p>
<p>Thanks for responding. I showed the piece to someone locally and they said it was because the clay was marbled. It cracked where the two types of clay were joined. I recycle clay all the time and that was the first time that happened. Thanks again!</p>
<p>Norm,</p>
<p>Thanks for responding. I showed the piece to someone locally and they said it was because the clay was marbled. It cracked where the two types of clay were joined. I recycle clay all the time and that was the first time that happened. Thanks again!</p> Bisqued ware fired to ^6 whic…tag:cone6pots.ning.com,2014-11-09:2103784:Comment:1157092014-11-09T09:41:35.039ZNorm Stuarthttps://cone6pots.ning.com/profile/NormStuart
<p>Bisqued ware fired to ^6 which cracks, with or without a glaze, is usually relieving stresses, from throwing or hand forming, as the clay becomes more plastic at temperature. Photos of the crack and where it is on the bowl would be helpful for others to suggest a cure.</p>
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<p>Highland Clay does not post COE numbers for their clay, so it's just a guess to think there's a COE mismatch between glaze and clay. But I think this is unlikely to be the problem just based on the way your…</p>
<p>Bisqued ware fired to ^6 which cracks, with or without a glaze, is usually relieving stresses, from throwing or hand forming, as the clay becomes more plastic at temperature. Photos of the crack and where it is on the bowl would be helpful for others to suggest a cure.</p>
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<p>Highland Clay does not post COE numbers for their clay, so it's just a guess to think there's a COE mismatch between glaze and clay. But I think this is unlikely to be the problem just based on the way your describe the damage to the body rather than the glaze.</p>