Ceramic fiber board

[davidh4976]

I'm thinking (which is dangerous)...

I've used ceramic fiber blankets in some raku kilns. I'm wondering about the pros and cons to using ceramic fiber board instead of blanket material. I can see how there might be a benefit to using it on the kiln top and bottom. On the bottom, it would give a firmer surface for placing kiln posts. 

• Is ceramic fiber board susceptible to water damage like the blankets?
• I'm aware of the health concerns with the blankets. Same with board? I would assume you take the same respirator precautions with cutting board as with blankets. But, when used in a kiln, I would think that there is less hazard during firings from the boards than from the blankets.
• Is the required thickness of board the same as for blankets? I've used 2" thick blankets. Is 2" board equivalent, or more, or less?

[neilestrick]

Yes, still susceptible to water damage.

Yes, still dangerous but probably doesn't shed as much fiber as the blanket.

You'd have to check the specs to see if they carry the same insulation value.

High temp fiber board (the white stuff) is not at all durable. If you bump into it it's going to chunk or crack or dent. A coating may help. The low temp board (brown stuff) is more durable, but it's not rated high enough to be used as a hot face product in kilns. It could be used as a backup insulation, though, and could save some money there.

[Rae Reich]

Floor:  I wouldn’t rest weight in it in any case, it will compress and be unstable beneath posts and also acquire uncleanable debris.

Lid:  Board installed so it doesn’t abrade would be better than the fiber, although it may warp.

Walls:  If you’re used to avoiding fiber walls already, the board can reduce some anxiety since it’s less likely to send fibers into the air when bumped. 

[Kelly in AK]

This kiln was a delight. It’s two layers of 1” board, a top loader. The roof was changed since this photo. I started with the board, but the wear and tear of lifting it eventually caused failure. I switched to two kiln shelves topped with a layer of insulating firebrick. The floor was insulating brick as well. It was used for cone 03, which it reached with ease. I did a couple cone 6 firings too. 

Two things worth mentioning. One is that the surface of the board is delicate, but it was sturdy enough for the wall structure. The second is it shrinks quite a bit. I’m sure it’s listed in a data sheet somewhere, but it seems like it was around 10%. The inner layer of boards had to be re-fitted after firing a few times, to fill big gaps. And they also cupped a bit, from shrinking more on the hot side. 

Edited October 9 by Kelly in AK