Fused Glass Produces Honeycomb Effect

by Bob
(South Wales)

I did some fused glass with some orange Spectrum glass in my kiln a little while ago, at the same time some blue Artista glass.
The kiln shelves were laid with whiting and glass mixed on shelves, top temp was around 810C for a full fuse of some opaque white on top of the blue and orange bits.
It all fused together well, but the orange looks like honey comb from the back and does not look stable or safe.
Could anyone explain or give a reason for this to happen?

Milly's answer:
Thanks for your question Bob. Am I right in thinking that you're using Spectrum and Artista on the same piece of fused glass? If so, that could be causing the instability, as the CoE is different - 96 for Spectrum (if you're using System96, otherwise it's 90), and 94 for Artista - and the manufacturers don't recommend fusing them together. Have you looked at the fired glass through polarizing filters, to see if there is any stress there?
If it's stress-free, it could be possible that the orange is a striker - it changes colour at a given temperature. Spectrum do have an orange striker - maybe it's not reaching the top temperature consistently?
Also, is the glass opaque? I've noticed sometimes that the opaque glass does mottle a bit when taken to fusing temperatures.
Has anyone else out there got any other possible solutions, or direct experience of this?


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