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Mica Firing Temperatures

Click here for basic information on mica.

Mica powder can be used as an inclusion or it can be applied directly on top of a sheet of glass.  But whichever way it's used, one thing to realize is that mica behaves very differently when fired to different temperatures.  Here's a brief guide to how mica behaves in the kiln, beginning with uncapped mica that has been airbrushed, sifted, or painted onto the glass:

At temperatures below around 1350F (730C), mica does not stick to the glass very well.  To get good adhesion, the lowest temperature that will work consistently is around 1380F (750C). 

Firing in the range from 1400 to 1450F (760 to 788C), micas are fairly stable.  They cannot easily be scratched from the top surface of the glass, and can be used as tiles, platters, etc.

However, if you go much higher the mica starts to lose its stability.  By 1500F (815 C) it begins to burn off and higher temperatures can cause virtually all of the mica to disappear. 

Capping micas will help them reach higher temperatures than 1500F, but even capped micas can become lighter if soaked for a long time at 1500F or fired to higher temperatures.

Stay tuned for future tips, which will discuss more ways to use mica in fused glass.

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Copyright 2005 Brad Walker.  All rights reserved.

Thanks to Avery Anderson and other board posters for many of the mica tips.

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Copyright 2005-2006 by M. Bradley Walker.  All rights reserved.

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