Bullseye Glass and Devitrification

Just a quick post about the devitrification I have been experiencing on my fused glass work

I have been having quite a bit of trouble with devitrification on a number of items, not just cabochons. My first thought was to blame the firing schedule, then specific colours of glass.

In an effort to work this out I I talked to a much more experienced artist and found out something that was a little disappointing.

Fused Glass Cabochon Devitrified
Fused Glass Cabochon Devitrified

When we started our studio we purchased a large lot of Bullseye 90 fusible glass from a local glass business. As it was at a great price we were very happy with the purchase and probably didn’t do a great deal of research into its suitability for our needs. Took it all on trust, so to speak.

Well, I have now found out, and it has been verified by a couple of other artists, that Bullseye glass is prone to devitrification. I have been advised that it should always be capped, sprayed with anti-devitrification solution and crash cooled. Wow, does that explain a few things.

We are still very happy with the purchase of glass, just a little disappointed in myself that I didn’t do my research, and in the person selling it to us for not informing us of the issue. We did explain what we were using it for and also our lack of knowledge, so I thought he would have done the right thing. He did say he was focusing on COE 96 glass and now I understand why.

So a word of warning if you are starting out. Do your research, especially before committing to large purchases of materials that will be with you for a long time.

4 thoughts on “Bullseye Glass and Devitrification”

    1. The learning continues, though slowly sometimes. I still find devit an issue, regardless of how carefully I clean etc. The opals are the main issue but I hope to master it eventually.

  1. I am new to fusing and thought I was loosing my mind when doing my test tiles. What could I be doing wrong? I created 6 test tiles all at different process temps and Spring Green got devit on each tile. I was advised by a professional glass fuser what schedule to use and I cleaned glass with lint free towel and spartan glass cleaner (bought at Bullseye) .

    I am glad to hear the devit is not me or my kiln but also sad because I have a lot of Bullseye Glass. Thank you so much for this post. I understand you can sift clear powder on it and fire at 1425 which is a fix but also time consuming. I noticed the Striker Glass was the glass that had devit.

    What is crash cooling and can’t that cause your glass to break?

  2. Hi Laura.
    Crash cooling is opening the kiln to quickly bring the temp down, but not to the annealing temp. I used to do it but only occasionally now. Mainly when trying to stop the processing quickly or if time is a problem. It’s not really recommended, but I’ve never had a problem, other than some bits falling off the elements onto the piece as I opened and closed the lid. Just be sure to stay well above the annealing temp, usually 482 C.

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