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I have a new all-fiber kiln including the shelf. I have heard so much 'noise' about whether or not you can fire directly on the kiln washed fiber shelf OR you should use thin fire, I'm don't know how to proceed. Would really appreciate some advice. Thanks!

I use thin fire. Kiln wash is more difficult to apply or remove.

smallbitz wrote:I have a new all-fiber kiln including the shelf. I have heard so much 'noise' about whether or not you can fire directly on the kiln washed fiber shelf OR you should use thin fire, I'm don't know how to proceed. Would really appreciate some advice. Thanks!

I agree that kilnwash is problematic. Perhaps Primo would be OK? I dust my shelf with finely ground alumina hydrate. That works for me.

This thread is very timely for me. I am slowly re-provisioning my studio and recently purchased a new, all fiber kiln and fiber kiln shelf. I’ve completed the burnout and regidizing process. I have had concerns about the surface smoothness and overall shelf durability. My supplier has suggested, and sent me, “Fiber Board Shelf Coat” a high temperature coating cement. I had intended to apply and cook/cure the shelf tomorrow.

I am hoping the Learned Ones here can lend me some wisdom. Will this material result in a practical shelf surface? I’m not a big fan of shelf paper for most of my work and prefer to use kiln wash. I typically remove and replace kiln wash after every firing other than slump temps. Am I better off just buying a good mud shelf?


I’m brand new to all fiber kilns. I purchased this small 18” kiln as an introduction to see if I wanted to go with all fiber in my soon-to-be purchased larger kiln. I was intrigued by the thermal properties of a fiber shelf, but worry that it may not be practical.

Any input is greatly appreciated.

Sharol

Nothing like a regular kiln shelf for taking accidental abuse.
I built my own kilns and went with traditional kiln shelves.
In theory there is less thermal mass in the kiln because of the fibre shelf but by the time you solidify it with cement, I cannot visualize much benefit during heating and cooling or the saving of that much energy.

I never had any luck with a hardened fiber shelf. The first firing was fine, the next one stuck like crazy and tore a pit out of the shelf making it worse than useless because the glass was ruined as well. If you have a fiber shelf, I would always use thin fire. But I agree with Kevin, a regular shelf is way more durable by far.

Bullseye sells ABSOLUTELY the flattest kiln shelf out there.
Shipping cost might be a problem, but I think in the long run it would be worth it.
Shelves from a ceramic supply store may or may not be absolutely flat.
A flat shelf is really necessary for a lot of different kinds of firings.
Just my $0.02 worth.
The other Jim

I, too, use Bert's method. Alumina Hydrate works for me. I haven't used any hardener on the shelf, either.

July 2023
My brick kiln did the deja vu by continuing to fire despite the switch being turned off. After melting into the elements and many of the levels of firebrick I rebuilt it last summer. Happiness reigned for 12 months. Last night I noticed it was heating too fast and shut it off. This morning we noticed the room was hot. I opened it and viewed the white hot fires of hell. It had continued to heat at full tilt 12 hours later.

I'm looking at a Jen Ken AF3P 16 fiber model as we have moved to a house where we have to fire in the basement rather than in the shop between the house and the garage. The rapid heating and cooling is attractive.

The discussion of fiber advantages and drawbacks seems to have lagged as the last post is pretty old. Questions still linger.

1. How durable are fiber kilns? Have there been improvements in the last 5 years?
2. If the kiln has a fiber floor can I just use a regular kiln shelf for durability?
3. Is there a source for more information on the care and use of a fiber kiln?
4. How would firing schedules change? I imagine the physics are fascinating.
Thanks in advance for your input.

I have a Denver fiber kiln and 3 brick kilns. Firing in the fiber kiln is similar, the lid is fiberboard, the sides are the usual fluffy fiber wool. Call Jen Ken, they will advise you. Sorry you had runaway kiln.

I was just wondering what type of kiln controller you have and whether it has a high temperature limit on it?

Gusglass wrote: ↑Sat Jul 22, 2023 1:38 pm 1. How durable are fiber kilns? Have there been improvements in the last 5 years?
2. If the kiln has a fiber floor can I just use a regular kiln shelf for durability?
3. Is there a source for more information on the care and use of a fiber kiln?
4. How would firing schedules change? I imagine the physics are fascinating.
Thanks in advance for your input.

I've owned two fiber kilns in my lifetime. A Jen-Ken Profusion 26 and a German-made Nabertherm GF240. Both are better made than the ones that Denver Glass used to make.

1. Most fiber kilns available today are better than the ones from years ago, which as Marion said, had the "usual fiber wool." More contemporary (i.e. better designed) fiber kilns have fiber board on the sides as well as on the top. State of the art is a brick floor, which helps with annealing, and lid elements in quartz tubes.
2. If you have a fiber floor (Jen-Ken makes both types) you can place a regular shelf on top and all will work just fine.
3. The manufacturers should be able to help with care and use, but it's not that different from a brick kiln.
4. Firing schedules don't really change that much. Although you CAN fire them quicker on the way up, the glass doesn't usually allow for that. With a regular ceramic kiln shelf they don't cool much faster than a brick kiln (with a fiber shelf or floor they cool a little faster).

Regarding durability, I used my Nabertherm for 12 years, then sold it to another person who's still using it 4 years later. I've had the Jen-Ken for four years now, it's still in at least as good a shape as a brick kiln of a similar age. The Denver kilns, which I haven't owned but have heard lots of stories about, tend to rust and aren't as durable.

One nice thing about fiber kilns is that the lid is lighter than brick kilns. Another is that they tend to use less electricity than brick kilns.