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Spicules and refiring a piece thicker than 6mm

Posted: Sun Mar 13, 2016 1:55 pm
by Bob Urrea
When you fire a piece thicker than 6mm with dams and get the irregular little spicules or irregularities along the edge which require cold working, how do you prevent it from recurring when you have to put the piece back In the dam again with he same 1/8 " type of dam to fire polish the edges? Thanks for any input.

Re: Spicules and refiring a piece thicker than 6mm

Posted: Sun Mar 13, 2016 2:55 pm
by linn keller
bob,
if i understand your question correctly, you're talking about prevention after you've done the cold working....in my experience, fire polish temp won't be high enough or long enough to cause the glass to move. i'm sure there's a kiln somewhere that belies that statement, but if i were worried i'm make a test run and see exactly what happens at what temps/time.
good luck,
linn

Re: Spicules and refiring a piece thicker than 6mm

Posted: Sun Mar 13, 2016 4:34 pm
by Bert Weiss
If you line the dam with 2 pieces of thin fiber paper, and the inner piece sits lower than the glass is thick, this will mitigate the tendency to make the spikeys. In other words if the glass is 7mm thick, make the inner lining 6mm high.

Re: Spicules and refiring a piece thicker than 6mm

Posted: Sun Mar 13, 2016 11:37 pm
by Warren Weiss
If you are only going to fire polish temperatures (1260 for 5 to 10 min) you should not have to dam it.

Warren

Re: Spicules and refiring a piece thicker than 6mm

Posted: Thu Mar 17, 2016 12:33 am
by Bob Urrea
Thank you All for your input. Fire polished with your recs and had a nice soothing edge with no spicules.