Slumping into deep square mold

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Wrangell
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Joined: Fri Apr 14, 2017 9:07 pm

Slumping into deep square mold

Post by Wrangell »

While most of our molds are B.E., we ended up buying some molds on eBay from someone who is getting out of fusing. This mold was kiln washed but never used.
It is not a BE nor does it appear to be a slumpys as far as I can tell from research. The mold measures 12" at the top and the sides are 45 degrees with the bottom base of the mold being 5-1/2" square. It is fairly thick (7mm) and seems well made. Since there were no holes, I did need to drill 4 vent holes in the bottom corners where glass will touch down last.

Am wanting to slump a 9mm thick piece into this mold so so since the piece is only 9" x 9" it is not dropping the full distance. With that said, the 9" square has to drop 2" to reach the base. I have read on other posts here that slumping into deep square molds you can end up getting a dogbone affect. Would rather not practice on this piece as it is combination of B.E French vanilla, Dense White with Cyan sandwiched in between these two. Here is the schedule I am thinking of using..

200F 1000F :20
150F 1225F 1:30 (monitoring at slump temp)
AFAP 900F 2:00
150F 700F :0

Have very little experience with slumping but have done a lot of research. Most of this research comes from this site and BE site. We do subscribe to their videos as well and these are very helpful in the learning phase.

The kiln I am using is an Evenheat Studio24 (side and top elements) interior dimensions of 22" x 22" x 13" deep.

Any feedback would be much appreciated. Can include pictures if need be.

Thanks
Jon
Brad Walker
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Re: Slumping into deep square mold

Post by Brad Walker »

First, this is a really difficult mold to use well. It's most likely made as bisqueware and not for slumping. Being 9mm thick gives you a better chance of succeeding that being 6mm thick, but you'll not only have to worry about dogboning you'll also have to deal with the potential for uneven slumping in the mold.

Second, I would fire lower and hold longer than you suggest.

Third, make a practice piece and try slumping that first.
Wrangell
Posts: 12
Joined: Fri Apr 14, 2017 9:07 pm

Re: Slumping into deep square mold

Post by Wrangell »

Thanks for the tips Brad. Going to forgo the square slump on this piece but will try it on another. Will take your suggestions into consideration when doing so.

Cut the square into a circle and now that raised some other questions that I'll put in another post. Appreciate the help.
Wendy
Posts: 3
Joined: Wed Jan 08, 2014 9:12 am

Re: Slumping into deep square mold

Post by Wendy »

I believe I have this mold. Mine has same measurements, and it is 4" deep. If you post a picture, I can verify.
After several practice firings, I have successfully used this mold with 6mm thick bullseye glass. I have started with 6mm thick pieces anywhere from 10"x10" to 12"x12", and have never had them slump unevenly. Just have to make sure the glass is level in the mold before firing- use a level. Some dogboning does occur due to the shape of the mold(square steep sides). Sorry I don't have a picture of any of those pieces.
I could not get the glass to drop completely with long holds at anything below 1280F. In my kiln.
I use this mold in a Paragon 16" fiber fuse kiln- only has side elements. No top elements.
My schedule for 6mm thick BE is 200dph to 1225F, hold 90 minutes. 100 dph to 1280F, hold 15 minutes. anneal for your piece.
For practice firings, I tried long holds in increments between 1175F and 1275F, observing many times during process, and this is what finally worked for me to get the bottom of the 6mm thick glass completely down, with least amount of dogboning. Your glass is thicker/heavier, different kiln, so may slump at lower temps.
Also,remember this caveat about dense white 000313 from BE: "Firing above 1500°F/815°C for more than 15 minutes or firing slowly between 1250°F/677°C and 1500°F/815°C may result in an unstable glass."
Wrangell
Posts: 12
Joined: Fri Apr 14, 2017 9:07 pm

Re: Slumping into deep square mold

Post by Wrangell »

Square mold resize.jpg
Square mold resize.jpg (8.86 KiB) Viewed 6800 times
Thanks Wendy. This mold is 3-1/2" deep and 12" square. Will probably try a 6mm thick test piece when I go to use the mold. I ended up doing something else with the 9mm thick piece. Cut the square 10" x 9" piece into a 8-1/2" circle on the wet saw and then slumped it into the BE Classic round mold #8723. It turned out pretty well.
I did remember about the firing issues with the Dense White at certain temps. It turned out good. Will post a photo on another Topic as it raised a few questions.

Back to the square mold. It is a really nice size and I will try to figure out slumping into it the advice from you and Brad.
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