Jeff Brett on wed 8 dec 99
At the college where I work, we built a cast kiln as well based on the
design in Ruth Tudball's book. We made the mistake of salt firing our kiln
a number of times before coating with ITC 100. I now know that we should
have been more patient (but our students aren't always) and coated it
before any firings with soda or salt. We did use a standard kiln wash
initially (alumina and kaolin) but it wasn't very effective.
Once our term was over I had a huge job of removing castable that had
become severely eroded by soda before coating with ITC. In some areas I had
to remove an inch of eroded castable and this was after only 8 firings. It
was no fun crouching in the kiln grinding and scraping away the castable.
After removing eroded castable, I sprayed one coat of ITC 100, then
refilled areas with ITC 200 Ceramic Fill and then applied a second coat of
ITC 100.
We have fired with salt and soda extensively since the repair and it has
held up reasonably well. The expansion cracks have begun to erode but not
severely. The cast door has begun to erode alot around salting and burner
ports and will require replacement soon.
If I had not used ITC products I have no doubt that the kiln would be
destroyed by now, after only 30 firings. Use by our students is perhaps the
most brutal conditions a kiln may face. How it lasts in the long term
remains to be seen.
Because we fire the kiln using both soda (cone 8) or salt (cone 10) I have
observed quite a difference in how each affects the kiln. We typically use
5-6 kgs of salt to achieve good salt glaze but only require 1.5 kg of soda
(sodium Bicarb with 150g of Borax mixed in hot water sprayed with a garden
sprayer) to achieve good results. The wear is much less with soda I think
partly from the amount used but also the temp we fire to. Cone 8 with soda
can achieve remarkable variations in colour and the colour spectrum that
can be obtained is huge compared to cone 10 w/ salt. If I could convince
them to use only soda at cone 8 our kiln would probably last for many years.
I wish you good success with your kiln.
....Jeff
At 6:36 PM -0800 12/6/99, scei wrote:
> I am interested in hearing from anyone using the ITC Ceramics
>products to
> coat kiln interiors. How do they work? Are they durable? Anyone
>using them
> in Soda kilns with success?
>
> We have recently constructed a cast soda kiln based on a design in
>Ruth
> Tudball's Soda book. It is a great kiln with excellent firing
> characteristics. Our typical Alumina/Kaolin wash works okay but we
>were
> hoping the ITC coating would give better protection from the
>corrosive soda.
>
>From: S.M.Corporation
> Opp. college,
> Kalol (N.G.)-382 721
> Gujarat, India.
>Email: scei@wilnetonline.net
____________________________________
Jeff Brett
Lab Assistant - Fine Arts, North Island College
2300 Ryan Road, Courtenay, BC, Canada, V9N 8N6
Phone: (250)334-5055
Fax: (250)334-5018
E-mail: brett@nic.bc.ca
Web Site: http://www.nic.bc.ca
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