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soda firings. extending shelf life

updated fri 1 jun 01


iandol on wed 30 may 01

Dear Brian Molanphy,

I would not like to make that sort of prediction. Since your shelves =
seem to have had a good life so far, the coin could flip either way.

But I would be concerned about the technique you are using. Although I =
do not fire with Sodium carbonate I have done many salt firings in =
several kilns. It was my practice to restrict draft when introducing =
salt by closing the damper. This was thought necessary to keep the salt =
in the chamber long enough for salt to decrepitate (splinter =
explosively), melt and distribute itself on, around and under the ware. =
Even if I used the Sprayed hot Solution technique I would close the =
damper to contain the soda..

Were I to start Soda firings again (I'm tempted!!) I would seriously =
consider using an Alumina/Kaolin wash and wad the bottoms of the pots =
and I would remove the wash after every firing. If I did not want to go =
to the chore of wadding I would float #100 mesh alumina over the wash =
after it had dried. I would continue doing this until I was sure of the =
reaction between my clay, the soda and any other materials applied to =
the exterior of the pots. If I did not create a very fluid dribbly =
surface with a lot of "snotters" I would consider abandoning the kiln =
wash. Its main purpose is, after all, to act as a "diaper" which =
prevents adhesion to the shelf. Wadding is a way of working I like =
because it allows the undersides of pots to get glazed. I doubt if there =
would be sufficient access for the soda dust and mist to float through a =
maze of alumina sand grains.

Hoping that these opinions provide food for thought.

Best regards,

Ivor Lewis. Redhill, South Australia