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Causes of Devitrification

This is part two of a multi-part tip on the causes of devitrification.  Click here to go to part one.

5.  Higher temperatures are more likely to devitrify.  In general, glass can devitrify at or above 1300F/700C, but it is much more likely to occur at temperatures above 1500F/815C. 

6.  Longer time spent at higher temperatures is also more likely to lead to devitrification.  Minimize the soak time at your top temperature to help reduce the risk of devitrification.

7.  Devitrification is also less likely to occur if you use faster firing rates above 1300F/700C, and cool faster from your top rate to below 1300F.  This minimizes the time spent in the temperature range above 1300F where devitrification occurs. 

8.  The edges of a piece of glass (especially a large item like a bowl) are more likely to devitrify if they're too close to the side elements of the kiln.  This is because the edges will remain hotter for longer than other sections of the glass.  This additional time means that devit is more likely to occur because the edges spend more time above 1300F/700C.

Coming soon -- more causes of devitrification.

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Copyright 2006 Brad Walker.  All rights reserved.

Thanks to Graham Stone for some of the items in this tip.

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