Help on making a ceramic seamless kiln shelf

[Pamela B.]

I have an Evenheat oval kiln (2541-13) with a 3-piece shelf and have been wondering if I could make a large seamless shelf using clay. I have tons of low-fire clay but I don't know if that would hold up to repeated firings. As we have a world-class ceramic facility in town (the Archie Bray) I can acquire any kind of clay. I thought I would fire this shelf and then coat with kiln wash, but would glazing be preferable? What could possibly go wrong??

I thought about HD but read that it warps. Thought about refractory board, but I don't know enough about it. Suggestions and comments cheerfully accepted.

Thanks,

Pam

[Tom White]

My general feeling is that low fire clay is not the best shelf material for the rapid (compared with clay firing) temperature changes we use for firing glass. Another issue would be getting it flat enough to avoid trapping air under the glass with large items. Many here have suggested rigidized refractory board. With no experience with that material I have to leave that to those who have worked with it.

Best wishes,
Tom in Texas

[Bert Weiss]

I have an Evenheat oval kiln (2541-13) with a 3-piece shelf and have been wondering if I could make a large seamless shelf using clay. I have tons of low-fire clay but I don't know if that would hold up to repeated firings. As we have a world-class ceramic facility in town (the Archie Bray) I can acquire any kind of clay. I thought I would fire this shelf and then coat with kiln wash, but would glazing be preferable? What could possibly go wrong??

I thought about HD but read that it warps. Thought about refractory board, but I don't know enough about it. Suggestions and comments cheerfully accepted.

Thanks,

Pam

Pam

Fiber board on the floor is my recommendation. Look up refractory in the yellow pages of a large city and you will find a supplier. Other possible sources are listed under boilers, pottery supplies, insulation. 1" thick is a standard available thickness. Burn it out and use it. Some people rigidize and kiln wash theirs.

Kiln shelves are made with Mullite/corderite clay bodies in a few specialized factories. Even then many shelves are less than flat. The slightest variation can cause problems.

[Liam]

I'm in agreeance with Bert, use fiberboard on the floor for your shelf. I rigidized mine, which makes it sticky to glass. Some use kiln wash at this point, but I love J110 1/8" paper that brad sells on this board. I dust it with a little dry kiln wash then smooth out with a hake brush. This fills in the tiny divits and gets about a smooth a surface as you well get with anything else. Kiln wash also extends the life of the paper.


Liam

[Andrew]

My 3 part shelves drove me crazy. The solution I came up with was to order two 20x20 inch shelves from Ed Hoy and then bevel trim the corners so they would both fit in the kiln. At least now I can do two large pieces at once!

A fuser that I know uses refractory board, but says that it eventually breaks down.

Andy

[Pamela B.]

I'm continually flabbergasted and humbled by the generosity of all of you on this list.

Thanx for all your advice. I'm afraid I'll have to motor on over to Portland to experience a "big city." Ain't got none such-a thang in this y'ar state.

Pam

[Bert Weiss]

I'm continually flabbergasted and humbled by the generosity of all of you on this list.

Thanx for all your advice. I'm afraid I'll have to motor on over to Portland to experience a "big city." Ain't got none such-a thang in this y'ar state.

Pam

You mean they don't call it eMpTy for nothing!

[Pamela B.]

[You mean they don't call it eMpTy for nothing!]

Not for nothing. It's Big, it's Dry, it's very M.T.: 2-1/2 times the size of New England, with fewer people than New Hampshire (from whence I emigrated 13 years ago).

Pam[/quote]

[Diane Trepanier]

I went to a demo on Kaiser-Lee board at Vitrum studio. Petra, one of the distributors, has used K-L board for her kiln shelf for 7 years and never has had a problem. A little spendy, but worth it. Check it out.

http://www.kaiser-lee-glass-art.com

[Jeri D]

I have a jen Ken Oval 9 and the seam drove me nuts, aside from having an evil shelf. I cut a piece of board to fit the whole bottom and it's great to have.
I have a down side though and maybe it is the way I am treating it, don't know. Even after I rigidized it, it has been very tender, to say the least, and must be treated gently. when i first sanded it with 200 paper, it marked it quite a bit. i solved that by kilnnwashing it to smooth it out. Now my quandry is I have needed to fill in nicks again. Sanded it (not sure how much to do) and reapplied waash. It is actually flaking off in areas. That's something i need to resolve.
I use thinfire on top of it

maybe there is something like "Head and Shoulders" to stop the flakiness.
Jeri

[Catharine Newell]

I have a jen Ken Oval 9 and the seam drove me nuts, aside from having an evil shelf. I cut a piece of board to fit the whole bottom and it's great to have.
I have a down side though and maybe it is the way I am treating it, don't know. Even after I rigidized it, it has been very tender, to say the least, and must be treated gently. when i first sanded it with 200 paper, it marked it quite a bit. i solved that by kilnnwashing it to smooth it out. Now my quandry is I have needed to fill in nicks again. Sanded it (not sure how much to do) and reapplied waash. It is actually flaking off in areas. That's something i need to resolve.
I use thinfire on top of it

maybe there is something like "Head and Shoulders" to stop the flakiness.
Jeri

Jeri,
To really extend the life of your fibreboard shelf, place a sheet of 1/8" fibre paper over the entire shelf surface. Place thinfire between the fibre paper and your glass each time you fire. After firing, carefully vacuum up the thinfire (Hepa filter here...) and roll the fibre paper smooth and flat with a heavy tube of some sort. I am able to use the fibrepaper layer for months on end and my shelf is absolutely protected from wear and tear.

Good luck!
Catharine