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kiln wash recipes: for which shelves?

updated sun 31 mar 02


Brian Molanphy on thu 28 mar 02


sometimes readers post a glaze recipe, and soon after another post comes up,
asking, 'well, what cone?'

so with the kiln wash recipes, i have to ask, 'well, what kind of shelf?'
and 'what kind of atmosphere?'

i guess that some of the recipes recently posted are for mullite shelves,
but i use silicon carbide shelves. i guess that the kiln washes are used in
ordinary reduction firings, but i fire with soda.

so, are these various kiln washes useful any which way, like for my
conditions, or any other conditions? or are they limited to, say, mullite
shelves in ordinary reduction?

in particular, i wonder, would a kiln wash which included silica be
appropriate for any kind of atmospheric firing? i think it could make a
mess, when fluxed by ash or sodium.

thanks, brian

Craig Martell on fri 29 mar 02

Hello brian:

I use the same wash for salt and cone 10 R firings. I use silicon carbs in
the salt and crystars and advancers in the reduction firings. I use the
same wash for both. 75% alumina hydrate, 25% kaolin. I use wads for a lot
of the pots in the salt too and the recipe for wads is: 40% sapphire
kaolin, 10% ball clay, 50% alumina hydrate.

regards, Craig Martell in Oregon


Anne Wellings on sat 30 mar 02

A few years ago I used to fire a ^10 reduction kiln. We had some mullite
shelves and some Acme Marls high alumina shelves. We always used the old
standard 50% kaolin 50% silica kiln wash, which, of course, flaked horribly
and got built up in cruddy, uneven layers from all the drippy student pots.
So I decided to try adding some alumina hydrate to the kiln wash, since I'd
heard that was a good thing. I don't remember how much I added (I think it
was around 1/3 or 1/4), or even much about the results, except that this
kiln wash somehow ate into the better-quality high alumina shelves,
removing the surface in small patches. It did not do this to the mullite
shelves. This one instance did not destroy the shelves or even damage them
much, but I immediately stopped using this and went back to the old
standard. The point of all this is not that I know much about kiln wash,
but that a kiln wash can behave differently on different kinds of shelves.