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soda kiln/firing

updated mon 31 mar 97


Tom Gray on tue 18 mar 97

I have a 7 yr. old castable, catenary arch (30 cu.ft. approx.) with 1 inch
of high alumina fiber glued to interior with super adamant kiln cement. I
plan to start soda firing in this kiln within a couple of weeks, as we
seldom use it and it has depreciated out. My goal is to lengthen the
longevity of the kiln by leaving the fiber in place until it shows the
least sign of deterioration. I hope to get at least 3 or 4 "extra" firings
out of it this way. At that point I will tear out the fiber and put a new
blanket on outside of kiln. Has anyone had any experience with fiber
linings and soda? Is it in my best interest to tear the fiber out before I
begin, or go ahead as planned?
Also, does anyone on this list have experience with any techniques other
than spraying soda ash/water mix into kiln. I have checked out Gail Nichols
Web site ( Has any one else tried Gail's
Thanks for any and all help!
Tom Gray Pottery
Seagrove, NC
Carolina Clay, The ultimate websource for North Carolina pottery!

Richard Burkett on wed 19 mar 97

Tom Gray asks about soda firing:
>Also, does anyone on this list have experience with any techniques other
than spraying soda ash/water mix into kiln.

Sure. I personally don't enjoy mixing or spraying caustic solutions of
soda ash. I'd also rather the students weren't doing that either.

Here at SDSU we have been getting very nice soda glazes using sodium
bicarbonate (baking soda) in powdered form sprayed dry into the kiln
using a cheap Sears portable sand blaster. This is pretty easy to do,
and doesn't involve caustic liquids. The baking soda is sprayed in
at the usual point for salt glazing - around cone 8-9-10 for a cone
10 firing through four ports in the kiln located right above the burners.
The soda is sprayed down the length of the kiln in the combustion area
for maximum dispersion and time airborne. If the soda is sprayed directly
on pots, shelves or kiln walls a great deal of erosion of these surfaces
takes place, so that is generally to be avoided. Baking soda dumped into
the firebox of the kiln like salt merely forms a glassy puddle with little
glazing taking place compared to the spray method. We use about 8 pounds of
baking soda for a 25 cu. ft. kiln (stacking area) which gives a nice
pebble on most of the pots, with those in the middle getting a thinner
glaze (as in most soda firings).