search  current discussion  categories  kilns & firing - salt & soda 

the netherworld of cone 02 - 3 was re: fw: low temperature salt at

updated tue 16 mar 99


Rafael Molina on mon 15 mar 99


It's interesting that you mention this temperature range because I fire two
types of work at this temperature.

I fire to ^ 02 for maiolica and slipware. We use white earthenwares and
terra cotta clays which are decorated with slips/underglazes and transparent
glazes and Arbuckles white maiolica with overglaze stains respectively. I
prefer to fire to this temperature because I feel the body is less porous
and IMO more durable and the glazes are a bit more glossy.

I fire to ^ 2 when I use colored clays. We make our colored clays from a
white earthenware. We mostly marbleize clays and roll into slabs to build
with, but some students are more ambitious and try neriage. We either fire
unglazed or coat with a clear glaze depending on the surface texture
desired. At ^ 2 the body is quite nonporous and durable.

Speaking from experience, ^ 2 is probably approaching the upper limit before
these bodies begins to deform or melt. On a few occasions low fire white
earthenware and terra cotta have mistakenly ended up being fired to ^ 6 and
^ 10 with predictable results. At least the terra cotta stays in one blob
but the white clay melts and runs all over the place. It's a pain to clean


-----Original Message-----
From: Vince Pitelka
Date: Saturday, March 13, 1999 3:40 PM
Subject: Re: Fw: Low temperature salt at cone 1?

----------------------------Original message----------------------------
>In addition to this technique I've recently heard about a low temperature
salt/soda at the cone 1 temperature range. I'm very interested in learning
more about this process. Apparently, it's the same technique as high
temperature salt/soda for stoneware and porcelain, but it's at the lower
temperature for eathenware/terra cotta.
>One source of information about low salt was the recent article in CM abot
Stephen Robison and Kathleen Guss. There are a couple of images described
as being salt fired to cone 1. Perhaps, Vince can shed some light on the
materials and processes.

Raphael -
Steve and Kathy do mostly high-fire soda, but they have done quite a bit of
^1 soda on terracotta. I do not think it is as exciting as their wonderful
high-fire soda work, but I think that may be because of the terracotta body
they are using. That body gives a green-brown cast which I do not
especially like.

I have fired some of my coil-built jars with inlaid-colored-clay imagery in
the ^1 to ^3 range in salt and soda, and am very pleased with the results.
The body I am using remains porous, and absorbs quite a bit of soluble salts
which can effervesce to the surface later on. This has not been a problem
for me, but it might be with functional work. For functional pots I would
think a terracotta body would be more appropriate, so that one would be
approaching vitrification, eliminating the absorption of soluble salts. You
can play with the color using ocmulgee (no longer being mined), carbondale
red, or lizella, or by manipulating the fireclay/red clay balance and/or the
addition of fluxes in order to approach vitrification.

This brings up an interesting question. Most texts identify the normal
range of lowfire, midrange, and highfire, but then there is that
nether-world from ^02 to ^3 which is not included in any of those
categories. This is a very exciting range for terracotta functional ware
and for refractory sculpture bodies.
Good luck -
- Vince

Vince Pitelka -
Home 615/597-5376, work 615/597-6801, fax 615/597-6803
Appalachian Center for Crafts
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166