Is it possible to fix an internally broken piece of glass?
- April 29, 2014 at 8:03 am #10140GlasuniekParticipant
I have fused a double layered sheet of glass for a dish (6mm). The piece came out as one piece, but there is an internal crack. When I tap it gently with metal, I can hear it’s not a whole piece (although it looks like one). It may be caused by opening the oven to a ventilation opening a bit too soon;).
I refired, using the same schedule (Evenheat standard program for 6mm glass, COE96, medium). It comes out exactly the same way. I was hoping the crack would be fixed by the additional firing;(.
Does anyone knows a way to fix this? I’m actually quite happy with the way the design worked out and would like to keep it for slumping. I fused many times using this program and it always comes out ok.
Thanks for any advice you could give me.
LindaMay 1, 2014 at 5:45 am #13341Stephen RichardParticipant
are most commonly caused by the incorporation of incompatible glass. It can be caused by inappropriate firing schedules. You don’t tell us what the actual schedule was (each manufacturer has different ones). In any case, if you have a problem with a schedule, you normally need a different one for the next firing.
Stephen RichardMay 1, 2014 at 6:33 am #13342GlasuniekParticipant
Thanks for your reply. The glass I used is Spektrum, COE96. I’ll give the firing schedule in F:
1. Ramp in 400F/h to 450F, hold 15 min
2. Ramp in 400F/h to 1000F, hold 15min
3. Ramp in 500F/h to 1150F, hold 20 min
4. Ramp in 500F/h to 1450F, hold 15 min
5. Ramp AFAP to 980F, hold 60 min
6. Ramp 300F/h to 950F, hold 60 min
7. Ramp in 150F/h to 750F, then it’s done.
The dish is a 30 cm square dish, two layers of glass. Sorry for the cm;).
I bought the glass in a package of 13 sheets. All are labeled Fuse compatible. They come from a store specializing in glass where I buy all my glass. I used more sheets of the same glass and there where no problems.
You can just see a scratch on one side of the dish. After the second (same) firing the scratch was still there. I was brave and slumped it tonight and it looks fine so far. The oven is still too hot to properly open.
So I’m pretty sure it can’t be the glass. How could I alter my firing schedules? It looks pretty safe to me, lots of time for hold.
LindaMay 1, 2014 at 6:46 am #13343Stephen RichardParticipant
Are sure the mark that you now call a scratch like mark is a crack? Could it be a mark from the shelf that was not eliminated by the second firing? Often a flip to put the bottom up will remove marks from the bottom. Of course, you must fire the top again to fire polish.
Do not apolgise for using the metric measurement system. All the world outside USA and some parts of Canada use it. Imperial measurements are the past.
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