sealer for ceramic board

jerry keller · Post by **jerry keller** » Sun Jun 29, 2003 8:44 am

After sandblasting for 25 years, I find the components in the ceramic boards, and fibers, irritate my throat, and thus my creative desire to live forever. At least the fantasy keeps me popping up each morning....
The new kiln I've had built so far is brick on the floor and walls, but has an M board on the lid. 42x28x18". I've heard there is an " Irish Linen" material, refro sil? that can be used to cover over the board, and contain the fibers in place. I've also got a friend that put vermiculite over the board on the lid. Yep, kitty litter, compressed into nice sheets. But longevity for this stuff is questionable...
There will be elements hanging from the lid .
Any suggestions are appreciated. My grandchilren, if and when they arrive, will also be thankful!
Jerry

S. Klein · Post by **S. Klein** » Sun Jun 29, 2003 12:07 pm

Refrasil is a product of the Hitco Co. I managed to get a sample a few years ago and it works. It is green hence the name Irish. They make several products that have different temp ranges. At the time the minimum purchase was a very large and expensive roll. I didn't want to spend my grandchildrens inheritance. I have been using it to cover bricks on the side of my kiln because it reflects heat. At GAS I talked with a representative from Clay Art Center http://www.clayartcenter.com about a similar product that they have. It is white and has a finer mesh. I have since experimented with firing directly on this material and my green refrasil and it works!! no kiln wash or thin fire. It leaves the texture of the material on the glass. You certainly could use this material to cover brick or fiberboard. It tears and cuts easily so installation has to be thought out carefully. One note of caution. I was also told that at very high temps and after many firings, the material erodes. What that means at our temps I don't know yet. I am continuing to investigate this product....................steve

charlie holden · Post by **charlie holden** » Mon Jun 30, 2003 9:29 pm

Does anybody know if there is a boro based fiberglass cloth? I know that there is borosilicate chopped fiber. Seems like it would work. May even be what Steve already has.

davebross · Post by **davebross** » Tue Jul 01, 2003 5:07 pm

Here's two recipes for that vermiculite backup insulation. It's only good to around 1000 degrees F. and this recipe is done in large quantities so you may want to scale it down.

Recipe 1 - Pete Vanderlaan

3-5 five gallon pails of vermiculite. Find vermiculite at the garden supply.
25 lbs. fireclay or ball clay. Ball clay is easier to work with.
2-3 shovelfulls of portland cement

Recipe 2 - Dudley Gibberson

4 cubic feet vermiculite
One gallon cement
One gallon clay
3 gallons of water

If you have a concrete mixer that's nice, if you don't put it all on a tarp on the floor and mix it by pulling the corners or sides of the tarp, rolling the mixture back and forth and to the middle, gradually adding water as you go. Keep doing this until it gets dough-like, or sloppier if you want, and you're ready to go. Wear a respirator for the dusty part.

The vermiculite is doing the insulating work, the clay makes it plastic, the cement makes it harden. You can tune it to do what you want by changing any of these.

Dudley's advice on recipe 2... If you want a thin hard shell (1/4" that isn't very heat resistant) for the outside then double or triple the cement and cut down on the fireclay. For a more heat resistant mix for in close to heat source remove some cement and double or triple up on the clay.

Thanks to Pete Vanderlaan and Dudley Gibberson's "A Glassblowers Companion" book for the info on this.