How low and long to slump

[lorwolff]

I know of the usual slumping schedule for Bullseye, that takes the temp up to 1385. It works fine for most pieces that are full fused to 6mm.

My question is how to allow for a much thicker piece?
I have a pot melt that is probably a good 8 or 9 mm in the center. It does thin out a bit towards the edges.
I would like to slump it. I was guessing that the following schedule might work:

300 to 1000 d hold for :30
300 to 1370 d hold for :30
AFAP to 960 d hold for 1:30
100 to 700 d hold :05
AFAP to 50 d hold :05

I am totally guessing that a little lower top temperature, but longer hold would work.
If anyone can help me I would appreciate it.
Thanks.

[The Hobbyist]

I doubt the "usual" slumping schedule for Bullseye takes the temp to 1385. I used to slump at 1300-1350 but now I'm happy at 1250. Ticker pieces are not necessarily slower than others.

If you're looking for a schedule you can program and walk away --- forget it. I still have to peek at around the target temp to see what's happening. Very often the piece has already reached the target shape. Other times I have to add many minutes to get there.

For a piece that thick I would go VERY slowly to 1250 and check at around 1225. It may be done or you may need more time. I don't usually change the temp, just add time.

Jim "The Hobbyist"

[Marty]

I hope that AFAP from 700 to room temp just means that you're turning the kiln off and that your kiln will cool slowly enough to avoid thermal shocking the glass.

Some of us slump BE below 1200, we just hold longer.

[Bert Weiss]

when it comes to slumping, thicker heavier pieces fall easier. Gravity is your friend. Just slow down on the initial heatup. Heatshock is not your friend...

[lorwolff]

I sure don't know where I got the schedule that has me slumping so HOT.
I got a lot of very thick heavy bowls.
The pot melts that I was attempting to slump are super thick in the center, and the sides pulled in a lot of the futz from the sides of the molds.

** My question now is, can I re-fire these thick bowls and try to get them back to 6 mm and then slump again at a lower temp?

I have never tried this, but it sounds like it has been done.

[Andrea R]

I know of the usual slumping schedule for Bullseye, that takes the temp up to 1385. It works fine for most pieces that are full fused to 6mm.

My question is how to allow for a much thicker piece?
I have a pot melt that is probably a good 8 or 9 mm in the center. It does thin out a bit towards the edges.
I would like to slump it. I was guessing that the following schedule might work:

300 to 1000 d hold for :30
300 to 1370 d hold for :30
AFAP to 960 d hold for 1:30
100 to 700 d hold :05
AFAP to 50 d hold :05

I am totally guessing that a little lower top temperature, but longer hold would work.
If anyone can help me I would appreciate it.
Thanks.

I would go really slow after the hold with no AFAP. I would control it all the way to room temp. The glass is 9mm in center is not going to cool down the same as a thinner piece would.
Good luck!!