Anthony Wolking on wed 29 oct 97
Any advice will help,
I have a 45cuft. hard brick salt kiln that is about to go on its maiden
voyage into the firing cycle. I have followed the thread concerning ITC and
salt and have found it most helpful, yet I have sone questions.
Since ITC is a thermal coating and not a kiln wash do any of you still rely
on a alumina based wash to protect shelves, do you powder your shelves with
alunina, do you still use wadding at the base of each pot? All these
question apply if you have chosen to coat your shelves with ITC.
Also, what shelves are the best for firing in a salt kiln? In my experience
high alumina shelves become brittle and crumble and silica carbide glaze over
regardless of any treatment. Suppliers have suggested I go with a c-12 mis,
whatever that is. Any suggestions?
TIA and welcome me to the world of debt.
Anthony
rwolking@aol.com or to the list
Craig Martell on fri 31 oct 97
Hello Anthony:
I've used ITC in my hardbrick salter to protect the refractories but I
haven't used it on any of the shelves. I still use a 75% alumina batwash.
You might just try some pieces of old broken shelf coated with ITC and place
a non precious piece on it or them(depending on how many tests you do) and
see what happens.
As far as shelves go, I think the best thing currently available are
Advancers or Crystars, which are made by Norton. Well, they were made by
Norton but Norton was purchased by a French company and now it's Norton and
some other name too. I would suggest the Advancers over the Crystars
because of expense. The Advancers are going for about $129.00 US for a
12x24x5/16" shelf. They are light(about 9Lbs)and they also save space and
BTUs. They don't warp and are very strong. I've recently started using
Alumina Carbide shelves in the salt. I purchased them used from a nearby
potter and they have the best salt resistance of any shelf I've ever seen.
That doesn't mean there aren't better shelves for salt, I just don't know
about them. These are not High Alumina shelves, which I've used in the salt
and seen how unsatisfactory they are. The problem with the alumina carbides
is I don't know who made them or if they are still being made. Donna at
Firebrick Supply in St. Paul, Minn. is talking with some folks at
Norton-Whatever, to see if we can locate some.
Norton also makes a "sandwich bat", which is a cn-192 silicon carbide core,
coated with an-291 alumina, which is 91% alumina. Cn-192 silicon carbide is
recommended for salt firing. With the alumina coating, I would wager that
these shelves are very good for salt but I'm unaware of any testing that has
been done. They are 12x26x.8" in size, and larger sizes are available. The
cost is high. For 2 to 5 shelves you pay $189.00 US. I'll bet they are heavy
to lift too. The advantage to these shelves may be not having to scrape off
salt slag and residue after each firing. That is how my alumina carbides
are, no scraping. There is nothing in the shelf that will bond with the salt.
Perhaps this is all just too much to even think about but I thought I'd pass
it along anyway. When talking to Donna about shelves, I was visualizing
huge sums of money flying out the window. Yeah, I know, you get what you
pay for.
regards, Craig Martell-Oregon
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