Mica

[Stephen Richard]

I may be wrong, but it sounds like you may be using glitter rather than mica.  Mica has a very high melting temperature.  The coloured mica used for kiln forming is formulated for higher temperatures than coloured mica for glitter.

The only “problem” that I have with mica powders is that only a thin layer sticks to the glass, so I usually use borax with the mica to soften the surface of the glass a bit.  If I put a lot of mica between glass, I get lots of large bubbles.

So a solution for your material may be to fire twice – once to full fuse, second time add mica and take to a tack fuse.

Stephen Richard

blogs at: http://www.verrier-glass.blogspot.com/ and  http://www.glasstips.blogspot.com/