Totally WEIRD slump

Greg Rawls · Post by **Greg Rawls** » Wed Jul 16, 2003 7:53 pm

Made a round disk - 3/8" thick and used white, cranberry red, clear and a streaky red/white. Fused flat very nicely, cold worked the edges. During the slump it sort of misshaped (wish I could post a photo!). Instead of being round, it's kind of wavy on the edges. I've had slumps that went down off-center, but never wavy on the edges! And the waves are symetrical. Here's the schedule:
150 > 350 30 min
200 > 1000 0 min
400 > 1250 10 min
9999 > 960 120 min
100 > 740 0 min
300 > room temp

Any ideas?????

Greg Rawls · Post by **Greg Rawls** » Wed Jul 16, 2003 8:32 pm

I put pictures on my web site:

http://www.gregorieglass.com/Warmglass.htm

Lorelei · Post by **Lorelei** » Wed Jul 16, 2003 8:38 pm

I'll be thrilled when you find out, I had the same thing happen to a large fr. & st. bowl I slumped.

Kitty · Post by **Kitty** » Wed Jul 16, 2003 11:02 pm

looks like the opposing sides were made from the same pattern bar. is that right? i cannot say why, but maybe if the two flattened areas are of the same stock in the lay-up, it might be clue that there is something about them that caused the glass to pull in.

charlie · Post by **charlie** » Thu Jul 17, 2003 10:24 am

does the back of the bowl contact the mold everywhere? perhaps it wasn't at slumping temps enough time or high enough.

could it have hung up on something as it was slumping? i usually put a very slight bevel on the outside down edge of a blank so that it will slide better as it's going down the mold side.

what material is the mold? if steel, have you used it before? it could have warped at temp, and unwarped when it cooled. the glass would then have taken the shape of the warp.

Bert Weiss · Post by **Bert Weiss** » Thu Jul 17, 2003 12:29 pm

Greg

If I understand your schedule, perhaps you are heating too fast up to slump temp from 1000 and not soaking there long enough for the glass to relax in to shape.

Using float glass, I sometimes get a lot more "wrinkling" I like this effect and sometimes encourage it.

Ron Coleman · Post by **Ron Coleman** » Thu Jul 17, 2003 12:46 pm

I agree with Bert about the rate of firing above 1000. Just a little fast and the slump temperatue is a little high. Combine the fast heat and high slump temp and edges of the bowl that are near the elements will get soft first and start to sink before the rest of the piece.

I wouldn't think you'd need to go over 1175 with a 20 min soak for a piece this big, guessing 14-16 inches in diameter.

Ron

Debinsandiego · Post by **Debinsandiego** » Thu Jul 17, 2003 7:22 pm

I agree with the thought that you went too high too fast. That was my first thought.

Nice piece though. I checked out your site and I really like the MELLO WALL and URBAN FOREST.

Greg Rawls · Post by **Greg Rawls** » Thu Jul 17, 2003 7:42 pm

THanks folks - I'll slow down the temp from 1000 to slump. I'll also try beveling the inside edge. The mold was Bullseye that's been used many time. I did not kiln wash it as it had only been fired a few times since the last wash.