I bought a paragon kiln – SC2 – to fire paint on glass, although this is a fusing kiln I figured this would be fine for firing glass as you only need a temperature of 1250F.
The problem I have got is a white mist appears on the suface of the glass after firing which cannot be easily removed, if at all.
I fire on thin fire paper on a ceramic shelf and have varied the temperature to experiment.
Have you seen this white mist before? Is it that some glass does not like to be fired, I use antique cathedral, lamberts, artista etc.
I am wondering whether I should have garn for a bigger kiln that has heating elements in the lid for even heat distribution across the glass surface where as the one I have is from the back and the inner dimension is 7inchx7inch.
I am happy to keep experimenting with this kiln but am I wasting my time looking for the perfect result?
Milly’s reply:
This particular Paragon kiln is specifically made for bead making and jewellery, with it’s small chamber and elements at the back. Having said that, it should be possible to get some decent results, so don’t give up yet.
The ‘white mist’ you mention is called devitrification, and it happens when the glass crystallises on the surface, leaving an unpleasant scummy residue. It can be caused by firing dirty glass (is your glass scrupulously clean?!), or if the paint binders are not given the chance to burn off in the early stages of the firing schedule. Does your Paragon kiln have a kiln vent? It’s important to vent your kiln during the first phase of your kiln firing schedule – say up to 500C/930F. There are devitrification sprays that you can buy if this persists – you spray or paint them on the glass and let it dry before firing.
Then there’s your firing schedule. With the elements at the back, I would ramp the temperature up quite slowly – say 100C/212F ph – to 500C/930F so that all the glass heats evenly. Then you can speed up to top temperature.
I hope this helps.