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I have just fired using Spectrum glass a 12" plate red white and blue useing opalized glass. Fired on a clear base 400-1100 5min soak ,1100-1280 60dph 25 soak, 400 -1465 10 min soak.flash to 1100 150 - 965 55 min anneal off takes 8 hours to reach room temp. First fusing excellent. Tacked on stars same fiing schedule but only to 1400 excellent. Put it in a stainless plate mold went 400 to 1175 saok 10 min. Looked excellent. Put it in the plate stand early am and went to bed this morning it is in 2 pieces. What is strange the way it broke. It went at a 30 degree angle from the right edge. It got to the field of blue just nicked it then went almost straigh up. I have done this plate twice with it breaking the first time while in the stainless mold. The mpold you sag into its under a inch deep. Cant any body say why. I cnt' let the gods completely win. I am tempeted to use some BE glass and see if I get better results. The crack is wierd. you can see at the following place looked in cracked album.
http://www.picturetrail.com/gallery/vie ... omsfoolery


thanks Tom

Tom, you didn't say what you did for annealing the plate after slumping. I would suggest that you take a more conservative route with three layers and stress concentrations caused by the tack-fused stars.

Try a 960 degree soak for 45 minutes then 100 deg/hr to 750 then off. That will control the descent through the annealing range and hopefully remove the stress caused by the protruding tack-fused elements.

You might also consider slowing your ramp up because of the tack fused elements. Maybe 300 deg/hr.

Tony

BTW: what did you offer the kiln gods? obviously not enough...

Tom & Tony,
When I go to Tom's photo album it says "0" photos in cracked album and won't let me open it. I viewed all the other photo albums (?) what did I do wrong?

I couldn't open it either Glenda. But now it's there.

From the look of it the crack initiates along the blue/red - blue/white joint. I stand by my original recommendation that you need to be more conservative with your annealing.

Tony