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Kilnwash powder curiosity
Posted: Sun Apr 21, 2013 4:00 pm
by Nanette
At times I sprinkle kilnwash on the shelf for texture. After firing to approx. 1480 degrees I typically just sweep the loose wash/powder into the trash. Could that powder be reused or has all its value been fired out?
Just curious of others opinions,
Nanette
Re: Kilnwash powder curiosity
Posted: Sun Apr 21, 2013 4:13 pm
by Bert Weiss
After a firing that hot, it is not recommended to reuse it. As I understand it, this has to do with the quartz inversion that has taken place in the kaolin, which is half the ingredient list. The other half is alumina hydrate. I believe that if you use just alumina hydrate as your textural powder, you can reuse it over and over. I do believe there is a limit when some sort of chemical from the glass leeches in to it. But I don't think this comes quickly, and I can't say I've seen this in action.
You can get alumina hydrate from a pottery supply. The version I bought there was coarser than that used in Bullseye kilnwash. If your goal is to get texture, this should be just fine.
I really like using very finely ground alumina hydrate. The one I recommend is made by JM Huber and is called SB432 alumina trihydrate. The only source I know about is MF Cachat in Ohio. They cover the northeast, south to DC and west to Denver.