Building a propane based infrared heat kiln

Bob Paterson · Post by **Bob Paterson** » Tue Dec 30, 2003 5:56 pm

Anyone ever try making a glass kiln using a propane fueled, infrared ceramic heating system?

I took a class on traditional kiln fired glass painting from Kenneth Leap a couple of weeks ago. His work is awesome - http://www.jkennethleap.com/mainindex.htm

He used a Hoaf Speedburner II that took the glass from room temp, to 1325F degrees, and back down to room temp in less than 45 minutes. The US distributor for the kiln has information on the Hoaf Speedburner III on their website at:

http://www.fusionheadquarters.com/Pages ... Spee-24455

The Netherlands website for Hoaf is:

http://www.hoaf.nl/Engels/html/en-ovens.htm

Now as much as I like the kiln, I don't have $3,000 to pop to get one sent stateside. I'd also like to venture out into fused and slumped glass.

So, has anyone successfully tried fabricating a kiln like this using propane based ceramic heating elements. I already sent a couple of notes to companies making these sort of elements to see if they could be used in the application.

Let me know,

Bob (Houston)

Bob Paterson · Post by **Bob Paterson** » Tue Dec 30, 2003 6:05 pm

By the way, this is where I was finding the manufacturers of propane based heating elements:

http://www.infraredheaters.net/

I saw that the Spaceray RSCA series units heat up to 1800F.

Bob

Rebecca M. · Post by **Rebecca M.** » Tue Dec 30, 2003 6:29 pm

I took a class on traditional kiln fired glass painting from Kenneth Leap a couple of weeks ago. His work is awesome

Bob, sorry I don't know about the kiln, but where did you take the class? And how did you find out about it? I've looked at his site before, but didn't see anything about classes. I'd be very interested in taking one also. TY

Bob Paterson · Post by **Bob Paterson** » Tue Dec 30, 2003 6:46 pm

Becca,

The class was in Wheaton Village, Millville, NJ.

Kenneth is not only an awesome artist, but an incredibly patient and interesting teacher. He knows the history of glass painting thoroughly.

I have never painted in my life and the piece I did actually turned out alot better than I imagined it could! You can reach Kenneth by email to find out about classes: jkl@eticomm.net

There are not many choices out there in traditional kiln fired painting. I live in Houston and there is nothing here. I just took the 2 day class from Kenneth. It seems most of the choices in traditional painting classes are out East.

Enders Island has a full week of advanced stained glass which includes painting:

http://www.endersisland.com/reservation ... ventid=126

I also contacted Dick Millard - one of the traditional masters in glass painting. He hold a week long workshop in NH.

Be sure to pick up "The Art of Glass Painting on Glass" by Albina Elskus who worked with Dick Millard. Dick Millard also has a book which is out of print but can be purchased on eBay or Amazon called "Stained Glass Painting" co-authored by Anita & Seymour Isenberg.

Be sure to tell Kenneth that we chatted. Ask him about how well I can paint commas!

Bob

Bob Paterson · Post by **Bob Paterson** » Tue Dec 30, 2003 6:49 pm

More stuff on Kenneth...

http://www.wetcanvas.com/forums/showthr ... did=145135

Rebecca M. · Post by **Rebecca M.** » Tue Dec 30, 2003 8:17 pm

Thanks Bob! That's so close to home I can commute. Who knew? Cool. I went to a Dan Fenton class up in Buffalo and it was fantastic. I learned quite a bit, he's a great guy and very talented as well. When you're on your own with painting on glass though I've found it's a bit more difficult than I thought. For some reason I can't wrap my mind around the fact that I don't have to make my own light. I have experience with oils and watercolors, so I thought it would be pretty easy. Uh, nope. Not for me yet anyway, so another class will be great.
I've got both of those books you mentioned and quite a few more to study. I love using all the different mediums to paint with. I read about someone using Mountain Dew!
Anyway, thanks for the heads up. I'm going to check it out.

David Paterson · Post by **David Paterson** » Wed Dec 31, 2003 12:35 am

Most glass would crack if heated that quickly. You might get away with heating small pierces of thin material, but I dont see how it could work on larger or thicker panels. Dont forget that if you paint on glass, the painted areas will absorb heat at a different rate than the clear, and each color will also absorb differently, causing uneaven heating.

And what about proper annealing? You can't possibly anneal and cool a painted piece of art glass in a few minutes, without trapping stresses in the glass.

Susan Moore · Post by **Susan Moore** » Wed Dec 31, 2003 10:25 am

Here's a link from the old archives you may find helpful

http://www.warmglass.com/cgi-bin/wgarch ... read=36910

David Paterson · Post by **David Paterson** » Wed Dec 31, 2003 1:54 pm

Interesting thread.

I am sure it works for firing paint onto 1/8" glass, however I doubt the usefullness on thicker pieces or on slumped work.

My experience on annealing slumped work is that you have to take the thickness of the mold into consideration, not just the thickness of the glass. This substantially ups the annealing and cooling time. If you use a drop ring made out of a 3/4" kiln shelf, then the parts of the piece touching the kiln shelf will cool much slower than the parts in the open air.

Also if you have an 18" diameter plate that is 1/4" thick, do you anneal and cool for a 1/4" piece of glass or a 18" piece of glass? If you cool quickly, the edges will definely cool faster than the centre, creating some residual stress.

A friend of mine makes large plates out of crushed glass. The crushed pieces are about 1/4" or smaller in diameter. First the glass is spread out on a kiln shelf about 1/2" thick and fused flat. Then the disc is refired and slumped into a mold. She had terrible problems with pieces cracking, even using an annealing and cooling time of between 12 and 24 hours. The edges of the plate were irregular because they were fused pieces of crushed glass. As a result there were hundreds of points that could start a crack running from the edge towards the centre. Even small stresses in this case caused cracking. She finally stopped making the pieces because of the extremely long cooling cycle needed.

Brock · Post by **Brock** » Wed Dec 31, 2003 2:00 pm

. . . I am sure it works for firing paint onto 1/8" glass . . .

That's precisely what it is for. Brock

Liam · Post by **Liam** » Wed Dec 31, 2003 2:52 pm

I messed with the idea of getting a speedburn kiln but the cost was prohibitive, and making one. Well I wasn't convinced that available ceramic elements could withstand repeted ramping. I aslo wasn't sure I would get even heat. I gave up and bought an electric fast ramping denver. They are thin walled so they cool pretty fast too. I usually crack the lid though. Lots of discussion about the high maintainance of denver kilns in the archives, but if you don't mind that, I get up to 1250 in 20 mins. I could go faster but what's the rush. I usually cool and have it out, after the firing in about an hour. There have been lots of discussions about more time needed for anealling, but I have never seen a stress problem under stressometer, or whatever its called. I'm thinking that the glass hardly moves, so no stress is created in the first place.
also:
I think
Stanley Klopfenstine
Glass Artist, KSG Studios
12 N. Brevard Ave.
Cocoa Beach, FL 32931
Phone: 321-868-0438
was also making and selling a fast electric kiln for painting. You might want to check with him. I believe that his consisted of a box with a sliding tray on the bottom. The tray slides in and out of the kiln, and the glass is set on this tray.

David Paterson · Post by **David Paterson** » Fri Jan 02, 2004 12:07 am

You ignore proper annealing at your own risk.

Normally you should hold the piece at the annealing temperature for at least 15 minutes, and more if the piece has any thickness. Then cool to the strain point slowly, before a more rapid cool to room temperature. The exact schedule would be based on several factors.

To determine the annealing point, a good rule of thumb is that it is about 50 degrees Centigrade or 90 degrees F below the point where the glass just barely bends under its own weight if a long piece is suspended between two supports.

The strain point for most glasses is probably about that much lower again. For example many float glasses anneal around 550 C and start to bend around 600 C. Below 500 C this glass is probably rigid enough to rapid cool without storing any stress.

Often, stresses stored in a piece wont show up for a long time, and then perhaps only if the piece is scratched or chipped. If you are planning to mount your creations in a public space, there might be liability issues.

If you want to see if a piece of glass has appreciable stress, after a test firing try cutting it, either with a glass cutter or a diamond saw, and see if any other cracks run off from the main cut. Or try drilling a few holes in it with a 1/4 inch core drill.

I know that industrially, 1/8 inch float glass is annealed and cooled very quickly. However this is done in custom designed ovens with controlled cooling from both sides.

The idea that "glass hardly moves, so no stress is created" has nothing to do with proper annealing and the stored stress that comes from not doing it right.

Don Burt · Post by **Don Burt** » Fri Jan 02, 2004 8:14 am

I think its proven that stained glass painting without concern for annealing can turn out a product that will last a few centuries. Maybe there would be fewer window cracks in medieval church windows if annealing practice was followed. But I don't believe its ever been much of a concern.

I would like to hear Barbara Cashman's practical experience about this. She's turned-out a lot of flat glass, where time is money. I would also think that stress on cemented-in tile would be more critical than in leaded glass.....less forgiving.

David Paterson · Post by **David Paterson** » Fri Jan 02, 2004 12:53 pm

The reason I am raising the issue of annealing is that it is a quick mental jump from firing enamels on small pieces of 1/8" glass, to using a drop ring for a slump of slightly thicker glass, to firing huge panels still 1/8" or slightly thicker, perhaps in a kiln of your own design.

Yet the annealing problems would be substantially different. The large homebuilt kiln might be substantially cooler at the edges than at the centre, depending on element placement, for example.

Friends of mine who are glassblowers used to make large plates, almost 2 feet across. One of them cracked badly while on display in a store window. If it had been a Chihuly style architectual installation, part of it might have come down on someone's head.

What happened? Well one possible reason is that when a plate is spun out the edge cools to below the annealing point very quickly, and the piece is now too big to be reheated. The centre is still soft and stresses badly against the edge even after sitting in the annealling oven for a few minutes.

If at this point the oven is brought down to room temperature in less than an hour, as previous posts suggest for firing 1/8" glass, then there woulds be huge stress stored in the piece. Yet large plates can be only 1/8" thick at the edges and slightly thicker in the center.

rosanna gusler · Post by **rosanna gusler** » Fri Jan 02, 2004 2:29 pm

apples and oranges. rosanna

Brock · Post by **Brock** » Fri Jan 02, 2004 2:30 pm

rosanna gusler wrote:apples and oranges. rosanna

Hah! I almost posted that myself. Brock

Clifford Ross · Post by **Clifford Ross** » Fri Jan 02, 2004 11:01 pm

everything that was blown in the class I attended was sat at anneal temp for a couple hours before slow overnight cooldown to room temp. I wouldn't think anybody would rush a cooldown with blown items that you put so much labor and sweat into.

Bert Weiss · Post by **Bert Weiss** » Sat Jan 03, 2004 1:07 am

I never heard of anybody building their own gas fired infrared kiln. They are cheap to run but expensive to make.

A company called Casso Solar makes lots of different infrared gas kilns. They can fine tune the job the heater does. For instance they can dry silkscreen ink without heating the glass beneath it by regulating the wavelength of the infrared.

Annealing 1/8" glass is a fairly simple task. Any thicker and it is a much more complex job. 1/4" anneals fine in a brick kiln as it can't cool too fast.

Barbara Cashman's mama kiln is can anneal glass pretty quickly as it moves it through the tunnel, cooling as it moves.

The challenge most of us have is cooling the kiln fast enough between 500 and 180. The tunnel lehr does a great job of that. All you need is 60 to 100 feet to get the job done.

Chihuly likes to work at factories with lehrs to anneal the blown glass. Teams can produce a lot of work in a little time that way.