I need help with a difficult slump

[Mary Price]

I am attempting to make a vase, which is made with System 96 glass. It is put together as follows: a clear circle for the center, then each of the petals is placed on the outside edge of the circle over lapping by about 1.5 inches. The petals also over lap a bit. I then place a second clear circle on the top of the petals. There are also strips placed along the length of the petal for added strength. The thicknesses vary from one layer to three layers. I have attached before and after photos. I believe it is a thermal shock, and here is my schedule. Please give me any advise on how to get this to work! I have had two come out great, and I have lost two.

75 degrees to 300 hold 15
150 degrees to 600 hold 15
300 degrees to 1050 hold 15
400 degrees to 1225 hold 25
9999 to 1000 hold 1.00
100 to 950 hold 2.00
100 to 800 hold 20

I have attached before and after pictures. I opened the kiln at 1075 to check on slumping.

Thank you!

[Marty]

OY


75 degrees to 300 hold 15 why?
150 degrees to 600 hold 15 why?
300 degrees to 1050 hold 15
400 degrees to 1225 hold 25
9999 to 1000 hold 1.00
100 to 950 hold 2.00
100 to 800 hold 20

Mary- you need to know why you're doing things. For starters slow things down. Try 100 dph to 1150, hold until slumped, then double your anneal. I don't know Spectrum's recommended schedules but I'd double them because of your irregular piece.

[Mary Price]

Thanks Marty, I'll give that a try.

[Warren Weiss]

Mary,
Your piece varies from one thickness to4. Bottom circle, 2 thickness of blue where the petals overlap and the top circle.
This high level of variation requires, as Marty said, a very slow heat up to avoid thermal shock. This variation also requires a very long aneal hold.