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bbates
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Thu Jan 24th, 2008 06:42 pm |
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I've heard various conflicting opinions on slumping and fusing with regards to the various styles of kilns. Are kilns with regular lids (coffin style?) better than clamshell style. We were concerned as to the speed in which air hits the hot glass when flashing the kiln. It has been a point of debate whether the clam shell style would allow too much air too fast thus stressing or cracking the glass.
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mmezalick
AGG member
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Posted: Thu Jan 24th, 2008 06:54 pm |
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Please excuse my ignorance but what is the difference between a "regular " lid (coffin type) and a "clamshell" lid.
I thought there was only a top loader and a side loader.
Michael
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bbates
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Thu Jan 24th, 2008 07:01 pm |
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I'm not certain of the proper terms, but I'm refering to regular lids (flat) and lid that are deep (clamshell)... Clamshells are like a regular kiln inverted...
You can see there isn't any sides to protect the peice from direct air hitting it when flashing.
Here's a link.
http://www.denverglass.com/cshell.html
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Mary Clerkin Higgins
Director
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Posted: Thu Jan 24th, 2008 07:32 pm |
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| It looks like the lower sides on the clamshell would be useful if you want better access to arrange your materials in the kiln for fusing. The top then swings down for the firing, so no cold air.
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mmezalick
AGG member
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Thu Jan 24th, 2008 07:32 pm |
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So it looks like your talking about kilns that have the heating elements on the top as opposed to having the elements on the sides.
Sound better?
Michael
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mmezalick
AGG member
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Posted: Thu Jan 24th, 2008 07:54 pm |
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Sorry, I think I am wrong.
It looks like the clam shell has a very flat bottom. Almost as if you turned the "regular" Kilns upside down. Other than the loading of the kiln with ease, without bending down, I don't' see a real difference.
Michael
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bbates
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Thu Jan 24th, 2008 07:59 pm |
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yes, but I didn't really want to say just that, our current kiln (RIP) is an old denver and all the elements are sticking off the lid, but it's not a clamshell because the lid is flat and one would set items down into the box of the kiln. With a clamshell, the kiln box lowers over the peices...
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Vic
Director
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Posted: Thu Jan 24th, 2008 11:17 pm |
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Since you should only "flash" cool the kiln till you reach the top of the anneling range (925-1050 degrees, depending on the glass) I don't see a problem with the use of either type of kiln.
Vic
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troymoody
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Thu Jan 24th, 2008 11:51 pm |
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There is really no reason to be flashing your kiln when fusing or slumping (unless you're just into that kind of thing). however if'n ya wanted to just for fun the clamshell will not give you any problems. i've done a fair amount with my paragon as well as other larger "bell" kiln and your new kiln will have a digital controller anyway... so once you get familiar with your firing schedules you'll be fine.
troy
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bbates
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Posted: Fri Jan 25th, 2008 01:33 pm |
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Thank you for all your responses...
Not to beat a dead horse, but I guess I should have been more clear as to what I am working with. My co-worker has a degree in glass blowing and has much experience with temperature shock when dealing with thicker glass. However, she has not had any experience with clamshell kilns in slumping and fusing.
Have any of you any experience with thick (1/2 inch+) glass in fusing or slumping?
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troymoody
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Fri Jan 25th, 2008 07:06 pm |
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i have completed numerous fused/slumped and cast commissions with 1/4", 1/2", 1" and some even deeper cast jobs. over the years i have worked with several studios who routinely produce cast glass for architectural installations using 1"+ float and last summer i created a dozen 36" fused/slumped discs as light fixtures for a San Diego resturant... ALL in bell kilns with no problems. most studios that work predominantly in large-scale kiln-worked glass are using this style of kiln, to be honest if you want to go big i can't image any other option.
any issues with thermal shock are MUCH more likely to result from your firing schedule then the kiln itself. although i was making a bit of a joke i honestly don't see why you would want to flash cool a fused project anyway. if you intend to fuse or slump glass this thick you are talking about some long firing cycles, the amount of time saved (by flashing) would be minuscule and not worth the risk. i'd say regardless of the type of kiln just perfect your schedules, trust your controller, shut the lid and be patient.
you might also want to check out http://www.warmglass.com. this is an online forum specifically for fusing freaks, there is a lot of information available and most of it is well founded.
you will definitely get conflicting opinions about kilns and everyone swears their kiln is the ONE TRUE KILN (glass dogma). i think you've just got to find one that suites your needs and then spend some time really getting to know the idiosyncrasies of your specific kiln.
good luck,
troy
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bbates
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Posted: Fri Jan 25th, 2008 07:43 pm |
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Thank you soo much for that last reply, very helpful!
I will pass this info on to my doubting co-hort...
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Dennis Brady
Non AGG Members
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Mon Jan 28th, 2008 12:19 am |
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There are many that believe opening any kind of kiln at top temperature is a needlessly risky adventure. Here's an article with a photo demonstrating what happens:
http://www.glasscampus.com/tutorials/pdf/Kiln%20Lid%20Dust.pdf
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Dennis Brady
Non AGG Members
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Posted: Mon Jan 28th, 2008 12:20 am |
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deleted.....
apologies for double post.
Last edited on Mon Jan 28th, 2008 12:21 am by Dennis Brady
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troymoody
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Mon Jan 28th, 2008 02:32 pm |
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hope it helps,
i am only speaking from my experience. i am not much of a "tech-head" and i am sure there are others out there with MUCH more kiln technology knowledge then myself. i had not even thought about the potential damage to your elements as shown in the above image. Reflecting back on your original question i realize you may have other reasons (other then flashing) for being skeptical about the clamshells or bell kilns. if you intend to do allot of physical manipulation of your glass while in it's semi-molten stage (anything where you open up a 1500 kiln and start poking around in it... i.e. raking a panel, embosing or recharging a lost wax mold) i could see the benefits of a coffin.
you'll probably have a lot more questions about types of shelves, brand names, controllers, ect, ect. check out other online fuser forums, visit and talk to other studios near you and call the kiln companies directly. Skutt is fairly easy to talk to and the folks at Bullseye are always helpful (they have a long history with Paragon).
Sincerely,
troy
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bbates
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Posted: Mon Jan 28th, 2008 06:30 pm |
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| We are leaning towards an olympic kiln. Does anyone have any objections?
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mmezalick
AGG member
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Mon Jan 28th, 2008 10:20 pm |
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Do we all get to try it out, at least once?
Michael
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bbates
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Posted: Tue Jan 29th, 2008 01:30 pm |
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Sounds good, if your in the neighboorhood, I don't object to visitors...
Of course, my boss might be a little less hospitible, who-knows...
So are olympic kilns pretty good?
The one we will be getting (pending the next large job) will be 30"x65"x15"
We hope to do some large fusing and slumping in it, too.
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Steve
AGG member
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Wed Jan 30th, 2008 02:14 pm |
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| I am curious as to why not rebuild the older Denver you have? Are there other problems with it? I have no experience with Denver kilns, so I know none of their weak areas, but seems it would be easy to replace elements ane your good to go. Am I wrong?
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bbates
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Posted: Wed Jan 30th, 2008 03:10 pm |
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Actually, nothing is really wrong with the old one, we just want the boss to pony up for a nicer biger kiln... lol, just kidding
No, the lid (metal) is warped pretty bad, so there is no good seal when firing.
We would have to get a new computer for it, since that is want seemed to go bad. Plus, I'm not really certain as to what else got damaged. It got up to somewhere between 2500 and 3000 degrees we are guessing.
The kiln was also very old and second hand at that. So, I really do think that it is time to get a new one.
I like having shiny new toys, especially when I'm not paying for it...
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