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OK, A stupid question about removing glass from a hot fire.
Posted: Sat Jan 24, 2004 1:42 pm
by hoknok
Is there a way to remove / tranfer glass when its above 1400F from the main firing kiln into a secondary annealing kiln. I know Hot Glass blowers do it all the time.
I would like to have my work removed from my mainfire kiln into a second holding place to allow for the slow cooldown phase. This would free up my main kiln for more production work. Is this being done already?
I figure my cool down "kiln" would not have to have any elements in it since it just a holding tank for the slow annelaing process to take place. I would just have a device to read the temp. Is my thinking flawed?
Much of my glass would be in molds and I would have ssteal hooks in place for the transfer. For my smaller sheet glass works, I would tranfer with tongs or ssteal trays.Is there a way to remove / transfer glass when its above 1400F from the main firing kiln into a secondary annealing kiln. I know Hot Glass blowers do it all the time.
I would like to have my work removed from my main-fire kiln into a second holding place to allow for the slow cool-down phase. This would free up my main kiln for more production work. Is this being done already?
I figure my cool down "kiln" would not have to have any elements in it since it just a holding tank for the slow annealing process to take place. I would just have a device to read the temp. Is my thinking flawed?
Much of my glass would be in molds and I would have steal hooks in place for the transfer. For my smaller sheet glass works, I would transfer with tongs or steal trays.
Re: OK, A stupid question about removing glass from a hot fi
Posted: Sat Jan 24, 2004 1:57 pm
by Brock
Is there a way to remove / tranfer glass when its above 1400F from the main firing kiln into a secondary annealing kiln. I know Hot Glass blowers do it all the time.
I would like to have my work removed from my mainfire kiln into a second holding place to allow for the slow cooldown phase. This would free up my main kiln for more production work. Is this being done already?
Normally, fusers just consider a firing a 24 hour event.
Fire today, open tomorrow
I figure my cool down "kiln" would not have to have any elements in it since it just a holding tank for the slow annelaing process to take place. I would just have a device to read the temp. Is my thinking flawed?
Yes. You would have to have a heat source in your secondary kiln, ESPECIALLY WITH CASTINGS.
Much of my glass would be in molds and I would have ssteal hooks in place for the transfer. For my smaller sheet glass works, I would tranfer with tongs or ssteal trays.Is there a way to remove / transfer glass when its above 1400F from the main firing kiln into a secondary annealing kiln. I know Hot Glass blowers do it all the time.
Re: OK, A stupid question about removing glass from a hot fi
Posted: Sat Jan 24, 2004 2:27 pm
by Brad Walker
hoknok wrote:Is there a way to remove / tranfer glass when its above 1400F from the main firing kiln into a secondary annealing kiln. I know Hot Glass blowers do it all the time.
Well actually, they don't. They remove it from a very hot furnace and work with it in the air. During that time, it cools rapidly from over 2000F to around 1100F or so. That's when they put it in the annealer.
I figure my cool down "kiln" would not have to have any elements in it since it just a holding tank for the slow annelaing process to take place. I would just have a device to read the temp. Is my thinking flawed?
Yes. Your annealing kiln will need elements in order to hold the temperature constant during the annealing phase. If you're doing castings or large pieces that take longer to anneal, then your annealing kiln will probably also need to have a computer controller. (Many blowers get away without one for thin-walled glass forms, but fused and cast works are more complicated to anneal than simple blown shapes. Annealing a large cast piece can take days, even weeks.)
Posted: Sat Jan 24, 2004 4:12 pm
by hoknok
Well thanks guys..
So I can remove the glass and move it over to an annealing kiln provided I do so before the temp drops to say 1100F. My glass will leave the kiln at temps around 1450 and higher and I would move it into the other kiln within 5 minutes or less.
As for the annealing kiln to have elements... It makes sense now. How else would I heat the annealing kiln to the approximate heat level the other piece is... at least above 1200f.. much less to annealing temps... duh!
Are people doing this? Is this a sound practice?
As for a 24 hour turn-around Brock mentioned. I assume this is for glass kilns only? maybe bell kilns?. My ceramic kiln retains heat very well. If I were to let my kiln cool naturally after a 1450 fire. the kiln would take 2.5 days to reach room temp. So on my last three fires, I have cracked the lid open about 1/4 inch to speed cooling once it hits 700F. This has worked for me without problems with the exception of trying to cool the kiln down from 300 to room temp quicker by opening the lid about an inch. All the tope layer pieces cracked. The middle and bottom shelved came out OK.
I have learned one thing... "glass is far more fickle than ceramics"!!!
Posted: Sat Jan 24, 2004 4:20 pm
by Brock
hoknok wrote:Well thanks guys..
So I can remove the glass and move it over to an annealing kiln provided I do so before the temp drops to say 1100F. My glass will leave the kiln at temps around 1450 and higher and I would move it into the other kiln within 5 minutes or less.
Well, you could, but where's the gain? Before you can use your original kiln again, it's going to have to cool enough not to shock glass or molds that you put in it.
As for the annealing kiln to have elements... It makes sense now. How else would I heat the annealing kiln to the approximate heat level the other piece is... at least above 1200f.. much less to annealing temps... duh!
Are people doing this? Is this a sound practice?
It CAN be done. I don't know anyone doing it.
As for a 24 hour turn-around Brock mentioned. I assume this is for glass kilns only? maybe bell kilns?. My ceramic kiln retains heat very well. If I were to let my kiln cool naturally after a 1450 fire. the kiln would take 2.5 days to reach room temp. So on my last three fires, I have cracked the lid open about 1/4 inch to speed cooling once it hits 700F. This has worked for me without problems with the exception of trying to cool the kiln down from 300 to room temp quicker by opening the lid about an inch. All the tope layer pieces cracked. The middle and bottom shelved came out OK.
Most 20 x 20 kilns can be recycled in several hours if the GLASS pieces are small enough. Once you get into bigger, brick kilns, cycle spans elongate tremendously. And, if you're firing multiple shelves in bigger kilns, you have, as you have undoubtedly found out by now. evenity issues to consider
I have learned one thing... "glass is far more fickle than ceramics"!!!
Posted: Sat Jan 24, 2004 4:25 pm
by Amy on Salt Spring
hoknok wrote:As for a 24 hour turn-around Brock mentioned. I assume this is for glass kilns only? maybe bell kilns?. My ceramic kiln retains heat very well. If I were to let my kiln cool naturally after a 1450 fire. the kiln would take 2.5 days to reach room temp. So on my last three fires, I have cracked the lid open about 1/4 inch to speed cooling once it hits 700F. This has worked for me without problems with the exception of trying to cool the kiln down from 300 to room temp quicker by opening the lid about an inch. All the tope layer pieces cracked. The middle and bottom shelved came out OK.
I have learned one thing... "glass is far more fickle than ceramics"!!!
You aren't letting the kiln cool naturally from 1450 though--you are letting it cool naturally from 700 which is where your annealing program should stop. You can crash cool from your high temp down to your annealing temp to shorten the time but this will also shorten the life of your kiln if you do it constantly. Time at annealing temp (around 960) and then a controlled drop to around 700-750 is prudent, so its only how long it takes your kiln to go from 700 to room temp. Cooling more quickly from 700 to room temp may work out sometimes but its risky. I think you are better off just getting a second kiln if you want to be doubling your production.
Amy
Posted: Sat Jan 24, 2004 4:27 pm
by Brock
You aren't letting the kiln cool naturally from 1450 though--you are letting it cool naturally from 700 which is where your annealing program should stop. You can crash cool from your high temp down to your annealing temp to shorten the time but this will also shorten the life of your kiln if you do it constantly. Time at annealing temp (around 960) and then a controlled drop to around 700-750 is prudent, so its only how long it takes your kiln to go from 700 to room temp. Cooling more quickly from 700 to room temp may work out sometimes but its risky. I think you are better off just getting a second kiln if you want to be doubling your production.
Amy
Amen, Sister. Brock
Posted: Sat Jan 24, 2004 4:39 pm
by Amy on Salt Spring
Brock wrote:
Amen, Sister. Brock
Why thank you sir...hey I like your Oscar Wilde quote...here is mine
"The soul is born old but grows young. That is the comedy of life. And the body is born young and grows old. That is life's tragedy."
Oscar Wilde
Posted: Sat Jan 24, 2004 4:56 pm
by Brock
. . . hey I like your Oscar Wilde quote...here is mine
"The soul is born old but grows young. That is the comedy of life. And the body is born young and grows old. That is life's tragedy."
Oscar Wilde
Oscar really did have a million of 'em. A truly brilliant mind capable of inspired, sardonic, and yet sympathetic wit at lightning speed. Brock
Here's another great quote, but not Oscar . . . .
When the French literary critic Sainte-Beuve, (1804 - 1869) was challenged to a duel by a journalist a century ago, and thus, according to custom, was permitted the choice of weapons, he told his opponent, . . .
" I choose spelling - you're dead ".
Posted: Sat Jan 24, 2004 5:52 pm
by hoknok
I think you are better off just getting a second kiln if you want to be doubling your production.
Amy
Well, if you want to get logical about this... (LOL)
sounds like a get to build my kiln this summer!
Thanks for the reality check..
Posted: Sat Jan 24, 2004 11:39 pm
by jerry flanary
In Czech bead factories they often have a full shelf of beads that they put in the bottm of a tall gas oven to pre heat. Once warmed they are moved higher in the oven. Finally in the top ranges the beads are fire polished and moved back down to the cooler section and finally dumped into a bucket where the warmth of previous beads all together help to reduce thermal shock. So this oven might have ten shelves full of beads invarious states of going up or down. The operator watches the ones in the top section the most. He loads the shelves when he has time and moves them in and out, up and down the oven (like pizzas)
I believe it might be profitable to take a similar approach and make fused slumped work in my glory hole and then put it in the annealler- One big oven at 900-1000 and one little hole at 2200.
Posted: Sun Jan 25, 2004 12:15 am
by hoknok
it would seem that your fused slump work would have to be small in size to fit in the glory hole? Also, how would you be able to ramp up the heat? Unless the glory hole was cool before the firing began, the glass would break in the thermal shock? And if you have to start cool in the glory hole, then why not do the whole thing an one kiln anyway like Amy suggested?
I still can't help but think there is a way to maximize firing in one kiln and then transfer to an annealing station. Especially if the annealing process was going to take weeks for cast work. Im am sure some large production house has already solved the matter?
Posted: Sun Jan 25, 2004 3:09 am
by Kevin Midgley
I have ten small kilns for the flexibility it provides. I can fire them 2 times a day and if I want to work around the clock and crash cool and then open the kilns at 700, I can do 4 firings a day. However each speeding up of the process increases the risk of producing cracked works. How fast do you really need something? Life is for living not becoming a slave to your kiln. I have used a stacking kiln made by Mercedes in Ontario that works well for firing painted glass. However, once again, you are a slave to your kiln for every five to ten minutes you open the door and move shelves. Once looked into conveyor kilns. This time you are a twinned slave to your kiln, one end loading the other end unloading.
Get a second or third or fourth kiln, relax and let the glass do its thing. The glass will be ready when it is ready. Nothing like the thought of rushed glass breaking several months after it has been sold to ruin a day.
Another problem with the make lots of glass idea is that before you can load a kiln you have to prepare the glass and that takes time too.
Kevin in Tofino..... who does NOT fire all his kilns all the time every day as that would be too much work.
Posted: Sun Jan 25, 2004 9:35 am
by Ron Coleman
hoknok wrote:it would seem that your fused slump work would have to be small in size to fit in the glory hole? Also, how would you be able to ramp up the heat? Unless the glory hole was cool before the firing began, the glass would break in the thermal shock? And if you have to start cool in the glory hole, then why not do the whole thing an one kiln anyway like Amy suggested?
I still can't help but think there is a way to maximize firing in one kiln and then transfer to an annealing station. Especially if the annealing process was going to take weeks for cast work. Im am sure some large production house has already solved the matter?
I think the main thing you're missing is that there will be no economy in having separate kilns and annealers for different stages of firing. The big difference between a fusing kiln and an annealer is only about 500 f.
The materials of construction have to be the same in either case and the difference in heating element requirements isn't worth worrying about.
If you're in a hurry, build 2 kilns.
Even if you have a kiln and an annealer, what are you going to do when you transfer a piece to the annealer and start the process of cooling and you have another piece in the kiln ready to anneal. Can't wait 2 weeks to start the annealing on the second piece?
Build 2 kilns, get on with life.
Ron
Posted: Sun Jan 25, 2004 12:17 pm
by hoknok
It seems the call of the second kiln is quite clear now. My summer project awaits me!
Thanks guys.
Posted: Sun Jan 25, 2004 10:19 pm
by watershed
Well as one of those Hot Glass guys, who also casts. The only time I would move a piece out of the casting oven, would be if I were REALLY stressed for time, and doing a slump AND casting in the same oven.
So bring it up, slump the thing, pull it, then go up to casting temps. I'd have to be pretty desperate, as even nice Kevlar gloves won't stand up to 1200 for long.
Good thought, but good you checked first, not CHECKED, later
I too have plenty of good ideas, that don't stand the light of day. That's why I bring them here.
Greg