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Devitrification, any fix after the fact?
Submitted by sherrieb on Sat, 01/23/2010 - 15:55.
Hi all,
still having fun with the new kiln (Caldera) and I was fusing some small jewelry pieces this time. Pieces on top shelf were fine, but most on bottom shelf have the "scum" on them. I've checked into the causes of this, and perhaps I didn't get them clean enough (would shelf lying on the kiln floor contribute?). Is there any way to correct it on those pieces, though, or are they garbage at this point? If garbage, does that mean just throw them out, or can I reuse in a pot melt or break them up to add to something else later?
thanks,
SherrieB
Sandblast and fire
Sandblast and fire polish.
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Paul
FusedGlass.Org
Helios Kiln Glass Studio
PaulTarlow.com
Sandblast and Fire
Thanks Paul!
SherrieB
Devit
This is an interesting subject because I have been firing some rather large pieces, and they break if cooled too quickly. I am having a hard time deciding how to cool them more slowly withoug risking devitirfication as well. And in your experience, fusers, would the devitification spray prevent both these occurrences? Thanks, Caren
devit
Hi Sherry,
Devit on cabs is usually caused by your not grinding the edge fine enough. Many people use a 120 grit bit to grind their cabs. If you fuse those, you will get scum. You need to grind much finer (320 minimum) and then add a light coating of some devit agent (spray A, clearcoat, etc).
As to cooling, devit forms above 1200°F. thermal shock happens below 1000°F. So if you crash your kiln below1200 you will not have to worry about adding to the potential of devit. Having said that, most of the major glass manufacturers' glass is devit resistant and will not likely have devit unless you are doing multiple firings or firing very high.
Barry
Barry Kaiser
Web Site www.kaiserglass.com
Glass Classes: www.Kaiserglass.com/classes.html
Tutorials www.kaiserglass.com/tutorials.html
Thanks Barry, This site is
Thanks Barry,
This site is so helpful! You all are so willing to share your experiences and knowledge!
Caren
devit
Thanks Barry!
SherrieB
Bullseye just sent out a
Bullseye just sent out a tech tip that suggests sifting a very thin layer (really just enough to cover the surface) of 1401 crystal clear powder and refiring to about 1435f for 10 minutes. Just tried it and worked great.
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Paul
FusedGlass.Org
Helios Kiln Glass Studio
PaulTarlow.com
Re: Bullseye tip
Thanks Paul, I will try that. My husband swears we have a sandblaster, but knows not where...
SherrieB
Wow - cannot imagine losing
Wow - cannot imagine losing a sandblaster - they are usually huge
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Paul
FusedGlass.Org
Helios Kiln Glass Studio
PaulTarlow.com
What did you use to sift
What did you use to sift that thin layer of powder? I tried this fix and my results weren't great because I couldn't get that thin, even layer I was looking for. Thanks!
devit
you can also use an eching cream and than re fire I have used etch all but any etching cream should work.
I have done this several times and it works really well , just make sure that you clean the piece very well after you etch the glass , It's like sandblasting without the blaster. )
Thomas Decker