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Fusing problems....
Posted: Sat Apr 10, 2004 8:49 pm
by Alan Cross
I am trying to slump some 4 mil float glass into a bowl shape I am taking it up slow to 1,500 and holding for 10 minutes....its all good except on one side the glass is all rough it looks like its not touching the side of the mould anyone able to help me with this problem? I do have vent holes in the mould.
Thanks
Alan
Posted: Sat Apr 10, 2004 10:34 pm
by Marty
Start by slowing down- 1500 is at least 250 too high. Could be the blank wasn't centered? Or you've got major cold spots?
Try a slower slump and look in at 1100 and 1200 to see what's happening.
What's the mold material? Kilnwashed?
Posted: Sat Apr 10, 2004 11:10 pm
by Alan Cross
Hi Marty and thanks yes it was kilnwashed and its a clay bowl I fired..I think my biggest problem was I was trying to fuse the edges and slump in one step maybe not a good idea...does anyone have fusing and slumping for float glass 3 and 4 mil?
Alan
Posted: Sat Apr 10, 2004 11:20 pm
by Bert Weiss
The roughness comes from having the air side down. 1550 is way too hot for a slump. 1250 - 1350 is plenty of heat. The glass needs to be level. go slowly and maybe soak around 1200.
If you are trying to fuse at the same time, don't. Fuse first and slump seperately. I fuse at 1420 with an hour long soak at 1220 on the way up and a 40 minute soak at 1420.
Annealing is important when the glass is 6mm or thicker.
Posted: Sun Apr 11, 2004 1:50 am
by Alan Cross
Thanks Bert I will forget the speed and go back to two steps and lower the temp!
Alan