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In the a few days I'll be doing something I've not tried before --slumping a very thick, assymetrically shaped piece of glass over a very large stainless S-mold.

Background: The piece is made of BE clear sheet and has been fired to achieve this thickness and the decorative elements several times already. It has an even 3/4 or 7/8" thickness (I haven't measured it to know for sure, but it's really thick and has very minimal bubbles inside). As for size, it's about 13 inches long and 12 inches wide at the longest point. At the shortest point it's about 5 or 6 inches wide.

I won't ramp it faster than 100F per hour at this point so I want to use secret the low 'n' slow (tm) technology for this piece. Does anyone have a clue as to what the top temp and hold time should be to avoid stretch marks?

Since the piece is assymetrical, one end weighs significantly more than the other. I'm wondering if there's going to be a problem with this weight difference when I slump it. For example, might it pull the piece off center on the mold?

Does anyone have any experience with trying to slump a chunk 'o' glass (tm) like this and have any pointers they'd care to pass along?

TIA -

Geri

Hey Geri,

I would ramp up like you were saying, 100F/hr
When I do similar things I hold at 1050 for and hour then ramp to 1100 at say 200F/hr and soak for another hour.

You're going to want to watch it to make sure it shines up the way you want.

Amy

Geri-Without seeing how you are going to set it up, it's hard to say what may happen. If you balance it on a high point, it will most likely not slip during the slump. Once the glass starts to move, the weight distribution does not change, and balance won't be thrown off. What could cause it to slip is vibration or movement. SS warping on heat up can cause some movement. I have done much bigger pieces and use a ramp up of about 170 deg/hr with good success. My kilns are all top fired. I generally don't go over 1250 for good slumps with minimal form marking. Good luck.

Geri Comstock wrote:In the a few days I'll be doing something I've not tried before --slumping a very thick, assymetrically shaped piece of glass over a very large stainless S-mold.

Background: The piece is made of BE clear sheet and has been fired to achieve this thickness and the decorative elements several times already. It has an even 3/4 or 7/8" thickness (I haven't measured it to know for sure, but it's really thick and has very minimal bubbles inside). As for size, it's about 13 inches long and 12 inches wide at the longest point. At the shortest point it's about 5 or 6 inches wide.

I won't ramp it faster than 100F per hour at this point so I want to use secret the low 'n' slow (tm) technology for this piece. Does anyone have a clue as to what the top temp and hold time should be to avoid stretch marks?

Since the piece is assymetrical, one end weighs significantly more than the other. I'm wondering if there's going to be a problem with this weight difference when I slump it. For example, might it pull the piece off center on the mold?

Does anyone have any experience with trying to slump a chunk 'o' glass (tm) like this and have any pointers they'd care to pass along?

TIA -

Geri

I have posted neumerous times on slump technology

Have a look at

Baffle n Go

As specifically 2 ur Q

I would put in warm kiln ( hand warm ) on cold SS mould

If side elements baffle em

Go at 100f from start do not open door peep at glass

B4 glass starts 2 slump go even slower

Say 50 - 75 F hour

MayB even hold temp if U feel the urge

When done cool a little then aneal start at high temp

Brian

Tony Serviente wrote:Geri-Without seeing how you are going to set it up, it's hard to say what may happen. If you balance it on a high point, it will most likely not slip during the slump. Once the glass starts to move, the weight distribution does not change, and balance won't be thrown off. What could cause it to slip is vibration or movement. SS warping on heat up can cause some movement. I have done much bigger pieces and use a ramp up of about 170 deg/hr with good success. My kilns are all top fired. I generally don't go over 1250 for good slumps with minimal form marking. Good luck.

i don't understand this. balance is done by gravity, which can be thought of as vertical force vectors acting upon a mass. if the mass moves position, then the vector moves, which would cause the center of gravity of the mass of glass to shift.

[quote="Geri Comstock"]In the a few days I'll be doing something I've not tried before --slumping a very thick, assymetrically shaped piece of glass over a very large stainless S-mold.



So how did it go? Just curious (mellow). Gotta do one similar, into a mold that I have yet to make of hydroperm. Plan to do a test run, but it'll be a few days before the mold is ready. So, back to you, got a photo? Advice? En/dis-couragement?
Yo

By an odd coincidence, the piece is in the kiln right now, slowly moving down toward annealing temp. It's about 3/4" - 7/8" thick so I ramped it at 100F to 1000 and held it for an hour...It hadn't started bending yet, so I ramped at 200F to 1150, held for 10 minutes and it finally bent.

I won't know for sure if I got the desired result until it comes out of the kiln, but it appears not to have slid on the mold when I peeked at it.

Good luck with yours!

Geri