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Haze on underside of bowl
Posted: Wed May 28, 2003 6:53 am
by Val
I keep getting a haze on the underside of clear bowls when slumping. This doesn't appear to be devitrification. I have used 2 different molds and have the same problem. It doesn't feel rough but looks like it is cloudy. tried various rates (all slow) nothing seems to help.
Can anybody please help.
Val
Posted: Wed May 28, 2003 8:34 am
by Barbara Muth
do you fire on thinfire? I know someone who has reported that when she full fuses clear glass on thinfire, she often gets a cloudiness when she slumps.
Barbara
Posted: Wed May 28, 2003 9:04 am
by Jane Lindell
What kind of glass are you using? Has the bowl already been fused?
What temperature are you slumping at?
Some more details will help.
Posted: Wed May 28, 2003 1:01 pm
by Val
I'm slumping a fused blank, base is Spectrum 96 clear, straight on kilnshelf.
Rate 370 to 1250
hold 20 minutes
then as fast as possible to 950
hold 30
Posted: Wed May 28, 2003 1:10 pm
by Cynthia
This is a long shot, but...If you look at the haze, is it an overall haze, or can you discern a faint repeated pattern like a bar pattern? I had some Uro machine rolled clear that was somehow contaminated in the manufacturing process and you could see a haze that looked like roller marks on the glass. Subtle, but unmistakably a bar pattern.
If it's that your best bet is to clean the glass ultra clean with soap and water with a green scrubby and a good rinse and dry. And do this between firings as well. I didn't find any good solution
. Sometimes it was there and sometimes not, but you can see it on the sheet if you look closely enough too. Never showed up as a haze until the second firing.
Posted: Fri May 30, 2003 8:44 pm
by Val
Thanks all who replied. Looks like your longshot was right Cynthia. I used a different sheet of glass and all is well.
