Kiln atmosphere and devitrification

Sean Albert · Post by **Sean Albert** » Wed Dec 10, 2003 7:27 pm

Hi, my name is Sean, I have question regarding the contamination of the atmosphere in an older kiln Iâ€™m using. Iâ€™m fusing Bullseye glass and have had devitrification problems. I put all new elements in the kiln, and am positive the kiln is powerful enough to reach desired temperatures at speeds that donâ€™t cause devitrification. I'm also using alcohole to clean the glass. The kiln has been used for lots of different things, including kiln casting in plaster molds. Is there any way to clean the atmosphere, maybe by holding the kiln (empty) at a high temperature? Or is it a lost cause. Just a shot in the dark. Thanks Sean.

charlie · Post by **charlie** » Wed Dec 10, 2003 8:11 pm

glass devits. it's not the atmosphere (which gets replaced every time you open the lid) or anything to do with the kiln.

use an anti-devit spray and it should go away. search the archives for any number of solutions that can be used.

The Hobbyist · Post by **The Hobbyist** » Wed Dec 10, 2003 8:35 pm

If you are using denatured alcohol it could be the additives they put in it. I have had devit-like streaks and I believe it is from the alcohol. I usually do a final cleaning wipe with it and I think that's where I'm getting the streaks.

I'm switching to rubbing alcohol or maybe even Everclear if it isn't too expensive.

The Hibbyist.........................................Jim

Andrew · Post by **Andrew** » Wed Dec 10, 2003 11:09 pm

Is it Bullseye fusible? Are you mixing fusible and non-fusible Bullseye. I have some green cathedral non-fusible bullseye that devits. Charlie's right though. Glass devits sometimes even when you regularly pay homage to the kiln gods . . .

AW

Andrew · Post by **Andrew** » Wed Dec 10, 2003 11:09 pm

Is it Bullseye fusible? Are you mixing fusible and non-fusible Bullseye. I have some green cathedral non-fusible bullseye that devits. Charlie's right though. Glass devits sometimes even when you regularly pay homage to the kiln gods . . .

AW

Sean Albert · Post by **Sean Albert** » Wed Dec 10, 2003 11:46 pm

Yes it's Bulleye fusible and compatible, I called BE and they said once a kiln has been "contaminated" there is nothing you can do to fix, well they didn't know of any way to fix it, and suggested this website. I haven't had much luck with oversprays, is there one which is more highly recomended. Oh and I've been using isopropyle alcohol as recomended by lot's of people including BE to clean my glass before fusing. Thanks so much for the help so far, you guys are so fast!
Sean.

Bert Weiss · Post by **Bert Weiss** » Thu Dec 11, 2003 12:44 am

sean wrote:Yes it's Bulleye fusible and compatible, I called BE and they said once a kiln has been "contaminated" there is nothing you can do to fix, well they didn't know of any way to fix it, and suggested this website. I haven't had much luck with oversprays, is there one which is more highly recomended. Oh and I've been using isopropyle alcohol as recomended by lot's of people including BE to clean my glass before fusing. Thanks so much for the help so far, you guys are so fast!
Sean.

Sean

I'd try and clean your glass with a final cleaning using water and a good rub with a paper towel. The ideal paper towel is Bounty Microwave. It is supposedly guaranteed to not contain metal particles which can scratch.

I don't much about kiln contamination.

I recently did some testing of different glass cleaners. Sprayway foaming cleaner is a good one. You can get it from your local window glass shop or CR Laurence. I used a clear glass cleaner from the grocery store that worked well. I ran out and don't have the name in my head. The trick is to get a no ammonia formula.

Everclear works but at $19 a liter it is not a great economy. Especially as bottles have a way of getting smaller and smaller. It think it easily evaporates. Or something.

Carol · Post by **Carol** » Thu Dec 11, 2003 1:40 am

I purchased a used ceramics kiln for fusing and everything I put in it had devit, plus it smelled terrible when fired. Tried firing it empty really hot a couple of times to get rid of contamination without success. Sold it to a potter for $100 more than I paid as it was no good for glass. You might just need to find another kiln.

Carol

Patty Gray · Post by **Patty Gray** » Thu Dec 11, 2003 2:22 am

Hi Sean,

Is it only certain colors or maybe only opals that show devit? If you are fusing with a glass that is prone to devit, either airbrushing or painting Super Spray onto the glass (let it dry before you fire) and you should be able to solve your devit problems. I find for cleaning glass I use just regular glass cleaner (no ammonia) and even on BE no problems. Some of the glass can be more prone to devit so if you make it a habit to clear cap or even use clear frit on top you can prevent the devit. Some only use Safeway glass cleaner. Different things work for different people.

I think what was causing Carol's problem in the old ceramic kiln was the use of some paints, lusters and such that will leave deposits on the elements. But you put new elements in so that shouldn't be the problem.

You might want to contact Rich at Kiln-tech @www.geocities.com/kilntec for some suggestions.

Good luck.

Patty
http://www.pattygray.com

Brian and Jenny Blanthorn · Thu Dec 11, 2003 5:50 am

charlie wrote:glass devits. it's not the atmosphere (which gets replaced every time you open the lid) or anything to do with the kiln.

use an anti-devit spray and it should go away. search the archives for any number of solutions that can be used.

In adittion

I vent the kiln till about 700 C

This gets rid of any smoky stuff which getrs on the glass n causes devit

If u got a few lifetimes spare there is a lot of devit stuff in the archives

An understanding of it will assist U in ur quest

Although there R those who actually like it

Brian

Amy Schleif-Mohr · Post by **Amy Schleif-Mohr** » Thu Dec 11, 2003 9:03 am

You don't say if you are firing on fiber paper. If so you should vent the kiln until 1000F or so, like Brian said. The fumes from the burn out can fall back onto the glass if they are not vented. It looks like devit.

Amy

Brock · Post by **Brock** » Thu Dec 11, 2003 11:20 am

. . . I find for cleaning glass I use just regular glass cleaner (no ammonia) and even on BE no problems. Some of the glass can be more prone to devit . . .

Even BE?

From the anecdotal information on this board Spectrum devitrifies far worse than Bullseye! Brock

Carol · Post by **Carol** » Thu Dec 11, 2003 12:58 pm

Patty Gray wrote:

I think what was causing Carol's problem in the old ceramic kiln was the use of some paints, lusters and such that will leave deposits on the elements. But you put new elements in so that shouldn't be the problem.

Exactly what I figured...was figuring some of those impurities also be in/on the bricks as well as the elements.

C.

Patty Gray · Post by **Patty Gray** » Thu Dec 11, 2003 1:00 pm

Hi Brock,

Yes when I fuse with BE or when my students fuse with BE they use regular glass cleaner. I use to use Sprayway but pretty much stopped after Avery said it caused devit on BE. I never experienced the devit from Sprayway but thought it would be a good change. Really the only time I experience true devit is with float glass and I always use Superspray with that (airbrush it on, let it dry).

Have fun with your Hawaiian classes, sounds great.

Patty
http://www.pattygray.com

Bob · Post by **Bob** » Thu Dec 11, 2003 1:19 pm

Sean,

I think taking the kiln to a high temperature and trying to burn off any contaminants is a good idea. If it is a ceramic kiln it will probably go to well above 2000F which is well above the working temperature for glass. Vent the kiln so the contaminants have a chance to escape.

I am surprised that the overglaze doesn't help... it should provide a protective coating. Also try firing quickly through the temp range that promotes devitrification... starting at 1375F.

Replace your kiln goddess... she ain't pulling her weight.

Cheers,

Bob

Dani · Post by **Dani** » Thu Dec 11, 2003 2:42 pm

I agree that before giving up on the kiln to fire it as hot as you can and vent the fumes. I would be surprised if you still have a problem afterwards. Lots of things can contaminate a kiln including wax from casting molds if it was used as a burn-out oven.... but, few things are so resistent that they won't burn off at a high enough temperature. Don't give up quite yet. And just for the record, I wasted way too much glass a few years ago believing the "won't devit" advertising. Do yourself a favor and just use an overspray on every glass. You won't even have to vent the kiln tbrough the nasty temp range. I use superspray or borax solution and just make sure you fuse at a high enough temp to avoid blotches. There's not a need to spray a second time and don't make the mistake of applying during a slump. Good luck!

daffodildeb · Post by **daffodildeb** » Thu Dec 11, 2003 3:47 pm

I didn't know about the ammonia based cleaners! Just to clarify, Windex, etc, is out, but 70% or 90% isopropal alcohol is ok??

Amy Schleif-Mohr · Post by **Amy Schleif-Mohr** » Thu Dec 11, 2003 4:12 pm

Yep, I just get the rubbing alchohol from the store.

Amy

Bev Brandt · Post by **Bev Brandt** » Thu Dec 11, 2003 4:34 pm

Bob wrote:Replace your kiln goddess... she ain't pulling her weight.

You know...my *neighbor* asked me about my kiln goddess. Which is odd considering my neighbor is a public health policy professor. Perhaps his wife - an ex-fiber artist - had a Loom Goddess.

Do these god and goddesses come to you or do you have to create them? I have some old Barbies around, perhaps one would like a promotion.

- Bev

Bert Weiss · Post by **Bert Weiss** » Thu Dec 11, 2003 5:25 pm

Bev Brandt wrote:
Bob wrote:Replace your kiln goddess... she ain't pulling her weight.
You know...my *neighbor* asked me about my kiln goddess. Which is odd considering my neighbor is a public health policy professor. Perhaps his wife - an ex-fiber artist - had a Loom Goddess.

Do these god and goddesses come to you or do you have to create them? I have some old Barbies around, perhaps one would like a promotion.

- Bev

Old Barbies are excellent. Recycling is very much encouraged this millennium. Smudge her with sage and she's in.

WarmGlass.com

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