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Anyone with experience on float glass annealing

I am very new in glass work. I have fused 2 pieces of 1/4 inch oval float glass, 22"x17", together and used hotline float glass powder to create a design on the glass. My fire schedule was
400/hr to 1000 hold:10
400/hr to 1200 hold:05
9999/hr to 1565 hold:25
9999/hr to 1150 hold:20
200/hr to 800 hold:20
100/hr to 600 hold:01
end
Everything turned out good, no devit, got a few bubbles, no big deal.
Now I have made a stainless steel mold oval, 12"x7", 6" high with sides that I will slump or drape over. My fire schedule is:
400/hr to 1000 hold:10
400/hr to 1200 hold:10
400/hr to 1325 hold:25
9999/hr to 1125 hold:60
200/hr to 825 hold:60
100/hr to 100 hold:01
end
On both fusing and slumping, am I being to conservitive or not enough?
I worry about annealing. This piece will be outdoors on a patio with lower winter temps and higher summer temps. I would like it to last. I would appreciate any help or comments. (I had said I was worried about tempering before, but I really meant annealing. Thanks for the input.)
Thanks, Shannon

Shannon,

Bert is the real expert when it comes to firing float.

I've never fired two layers of 1/4" float so I can't give much advice. However, I anneal my float at 1030 (lots of people anneal float at 1000) but I think for the thickness you're firing I'd be annealing longer than you are.

Also, I usually start my slump at a lower temperature than 400 dph.

I'm sure Bert will give you all the advice you need. Bert also knows all about tempering glass. As I understand from his posts this has to be done in another step by professionals.

Judy

Only flat glass can be tempered. Anything that has been slumped will not survive the tempering process because of uneven heating and cooling.

If you piece will hold water and you keep it outside don't let it freeze with water in it. If it's a table top or something that will drain all rainwater, it will probably be ok.

Ron

Shannon macklin wrote: <snip>
9999/hr to 1565 hold:25
9999/hr to 1150 hold:20
200/hr to 800 hold:20
100/hr to 600 hold:01
<snip>

I don't have Graham's book in front of my but I'm with Judy -- you're cooling much to fast after your anneal soak for 1/2".

Also, you shouldn't need the second soak during the anneal cool down. The point of the soak is to get evenity through the glass before the decent. If you don't still have that when you get to 800F then you probably created stress on the way there.

- Paul

I've seen some pretty radically bent glass tempered. Check this out http://www.europebynet.com/drilldown.as ... 382366&v=0. I was too skeptical to actually sit in it, but it's made for use.

i do not think that is tempered. rosanna

rosanna gusler wrote:i do not think that is tempered. rosanna

Let's buy one and smash it to see how it breaks

ooooh you heathen! i have been in love with that chair for years. i think i first saw it or one like it in 'kiln formed glass' by cummings. any how where ever i saw it, it is just too cool. do you think it was formed in one slump or two or more? hard to bend the mind around. start with a piece of flat glass, saw the appropriate slits/voids then slump at a low enough temp so as to not get texture............other than that, not much. rosanna... who now must go look for where she saw that chair

I was doubtful, but showroom associate at Corning said it was. Granted, that is not definitive, but imagine the liability issues of selling a glass chair, that could break into big dangerous pieces! The lawyers themselves would be hawking these things!

I think I would take my chances in a regular annealed chair. One little scratch in a tempered chair and you would be on the ground.

If the glass is thick enough there is no need to temper.

Ron

The chair is marvelous.
In my eyes it looks like a laminated form.

Btw. Who is the US guy who *casts* furniture in glass.
A huge "flowerpot kiln" with the mold velow.
I think it was mentioned here a year or so back.

-lauri

from 'techniques of kilnformed glass by cummings' ".......from a single piece of 12mm thick glass. the sheet of glass has a slot cut through it and is edge ground and polished before being slumped over a simple mould. great care must betaken to prevent the softening glass from being marked by its contact with the mould." i wonder how many rejects they got or if they got lucky on the first go. rosanna

i also wonder about the 150 kgs . did they break one or did they just chicken out at the 150 kg leval . can you see it? "ok ok ok..good enough...no more...don't break it for gosh sake! ...lol rosanna

lauri wrote:The chair is marvelous.
In my eyes it looks like a laminated form.

Btw. Who is the US guy who *casts* furniture in glass.
A huge "flowerpot kiln" with the mold velow.
I think it was mentioned here a year or so back.

-lauri

That would be John Lewis. He uses lots of glue as well.

http://www.johnlewisglass.com/

ch

Shannon

I don't have the time to focus on your schedule at the moment. My controller works differently than mostm so I think in different terms.

To anneal 1.2" float glass I drop to 1000 hold for 2 hours, take 2 hours to drop to 900, take 1.5 hours to drop to 700, 1.5 hours down to 300.

As far as reheating goes, it pretty much depends on your kiln setup.

For the fuse firing, I would take 1.5 hours to heat to 1000, take .5 hr up to 1220, hold at 1220 for 1 hour, take 45 minutes up to 1420 and soak there for 40 minutes, then drop to anneal.

To heheat, I would probably slow down the initial ramp to half as fast.

I'm not getting much board time in while teaching. Class is going well. Lots of hard work. midnight slump switch tonite. New kiln new controller.....

How many kilns one must have with those annealing times+

-lauri