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Prefired some vermiculite board to 1500. Applied alumina/kaolin wash in several coats—the board seems to suck out the moisture—and rubbed smooth with my palm. Fired some Bullseye to 1500 with a 10 minute hold and cooled. Glass did not stick. Repeated this test two more times without applying new wash. Glass still did not stick.

Next test was to carve a bit of relief in the surface of the board. Applied kilnwash, fired glass to 1500, again no sticking and glass picked up relief.

The vermiculite board is rather friable which makes it difficult to carve, but I can see potential for this technique. Your thoughts?

vermiculite is rumoured to be almost as bad as asbestos when it comes to dust control. it comes from the same mines and may have asbestos in it. i think you might want to encapsulate it before use.

Paul, do you think it would carve ok with a high speed tool? What were you using?

charlie wrote:vermiculite is rumoured to be almost as bad as asbestos when it comes to dust control. it comes from the same mines and may have asbestos in it. i think you might want to encapsulate it before use.

This is Skamol which I understand is asbestos free. But, I will look into it.

Paul Housberg wrote:

charlie wrote:vermiculite is rumoured to be almost as bad as asbestos when it comes to dust control. it comes from the same mines and may have asbestos in it. i think you might want to encapsulate it before use.

This is Skamol which I understand is asbestos free. But, I will look into it.

Here's the MDS:

http://www.skamol.com/pdflib/msds_US_A4_V-1100.pdf

Don Burt wrote:Paul, do you think it would carve ok with a high speed tool? What were you using?

For this initial test I simply used an old worn chisel. Some small gouges like one would use for linoleum or wood block printing would probably work. I think it could be carved with a high speed tool, but one wishes that the material offered more resistance. It would be dusty.

I'd like to get my hands on a small CMC machine for carving.

Paul Tarlow wrote:

Paul Housberg wrote:

charlie wrote:vermiculite is rumoured to be almost as bad as asbestos when it comes to dust control. it comes from the same mines and may have asbestos in it. i think you might want to encapsulate it before use.

This is Skamol which I understand is asbestos free. But, I will look into it.

Here's the MDS:

http://www.skamol.com/pdflib/msds_US_A4_V-1100.pdf

Here's the critical language from the msds:

"The vermiculite component of this product may contain small amounts (1% or less) of crystalline silica (cristobalite). Cristobalite is listed in
the State of Massachusetts as an Extraordinarily Hazardous Substance and carcinogen, when present in dust-producing material, but is
exempt if particulates are not present and cannot be substantially generated through use of the product. Crystalline silica whose particle
size is in the respirable range has been listed by the State of California as a compound known to cause cancer."

I would consider this a small and very managable risk. I think the exposure is less than when making plaster silica molds. A respirator is probably a good idea, but I'm not making any recommendations as to the use of the board.

the key phrase is is exempt if particulates are not present and cannot be substantially generated through use of the product.

i think it'd be good to use as shelves. i'd certainly wear a respirator when using metal whirly things to cut it.