Wednesday, 22 December 2010

Devitrification Prone Glasses

"Are there specific glasses that are more prone to devitrification, and knowing that, what steps can you take to try to avoid it?"

Glasses that are formulated and tested compatible for kiln forming are less likely to devitrify than other art glasses.

Opalescent glasses even if tested compatible for kiln forming are more likely to devitrify than their compatible transparent counterparts.

Yes, you can fuse some of the transparent glass made by a single manufacturer - Spectrum transparent and especially the water glasses are most often compatible within certain limits. But you will find that the edges show devitrification almost always. When using glass untested for compatibility, capping with clear glass often helps in reducing or preventing devitrification, as the clears seem less prone to devitrification than coloured glasses

You can clean very well and hope for the best, or you can clean and then use a devitrification agent - normally a flux or low firing glass in suspension - and spray or brush it on. If it is one of the low firing glasses in suspension, make sure you put it on before taking it to the kiln, as it will stick to other things when fired.

Another method is to avoid staying in the devitrification range of temperatures very long - both during temperature rise and cooling.

A description of what devitrification is

The temperature range in which devitrification occurs

A homemade devitrification solution