peachblow pottery on mon 2 apr 01
Several questions came in on my post to Iandol concerning Metallic Vapor =
Glazing. The workshop Iandol referred to may be very different from what =
I did, but his post took me back some years to a process that would =
certainly be considered metallic vapor glazing. Iandol and Brian =
Molanply both asked how I was introducing the copper. Copper carbonate =
was mixed with the rock salt and deposited in the kiln in the normal =
salting process. Sometimes tin chloride was added at that point also. =
The salt, copper and tin would vaporize and be carried to the pots as a =
vapor glazing process. Each consecutive firing would also have residual =
copper and salt left in the firebox, so probably from bisque temperature =
on some of the material was vaporizing on the way up to cone 8 or 9 when =
I would introduce more of the mixture. I never got to the sulphates, but =
I believe they would vaporize at an even lower temperature. Again, I was =
aware of Don Reitz throwing oxides and carbonates into his salt kiln for =
flashing of color, I wanted a more controlled process where the entire =
pot received the colored vapor. I had no problem using copper carbonate =
to get my copper red vapor glaze. Again, you will contaminate the kiln =
for consecutive firings so think twice before doing this. The tin =
chloride was again introduced in the cooling cycle for iridescence, what =
we called fuming. Since the sodium, copper, and tin are all metals, I =
consider this a metallic vapor glazing. I believe any metal that is =
vaporized is lethal, don't breathe the vapors of any salt kiln. And =
lastly, thank you Patricia for the hello, if you are in Mid-Ohio give me =
a call and come by. Tom Turner
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