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September 23, 2009

Five Tips for Successful Stacking in a Salt (or Soda or Wood) Kiln

by Michael Kline Read Comments (2)

Salt and wood fired bowl by potter Michael Kline. Long a process of industry, salt firing has also been embraced by ceramic artists and potters because of the beautiful and unpredictable results that can come from a salt-fired kiln. In this process, salt (sodium chloride) is introduced into the kiln firebox or burner ports at high temperature. The salt vaporizes and is carried on the flame to the ware.Then the sodium vapor combines with the silica in the clay surface and forms an extremely hard sodium-silicate glaze. As with any vapor firing process, pots need to be stacked in the kiln with wadding so that the salt glaze doesn’t adhere them to each other or the kiln shelf. Potters come up with all kinds of ways to make the wadding process as smooth and streamlined as possible (see Way Easy Wadding in the Ceramic Arts Daily Archives for another great wadding idea). Today, salt and wood firing potter Michael Kline takes us through his wadding process sharing his tips for successful stacking in the kiln. He also explains how he adds sea shells into the mix for a nice flashing effect. - Jennifer Harnetty, editor.


Here is a series of pictures showing how my plates are wadded and fired. This technique was developed by my buddy Will Baker way back when.

First, my wadding station has a soft surface that won’t chip the slip off of the pots. The wads are made with stiffer wadding (see recipe below) so that they won’t collapse under the weight of 4 or 5 plates. Elmer’s glue is dropped on all of the wads.
Broken-up sea shells from Pawley’s Island are placed on bottoms of the wads to make a nice flashing mark where the wad would have left just a dry white dot. The shells resist the salt and keep the plates from sticking, too.

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Sea shells from Pawley's Island are placed on the wads to make a nice flashing mark where the wad would have left just a dry white dot. The shells resist the salt and keep the plates from sticking, too.

 Then the plates are carefully stacked. Just as when stacking kiln shelves, where the posts have to be stacked one above the other, the wadding also has to be in line as shown at left.
At left is the actual stack placed in the kiln. On top of the stack are some cups that also have shells glued to the wadding.
Speaking of posts, a.k.a. kiln furniture, I wad all of the posts so they will stack without wobbling. Also the soft wadding conforms nicely with crooked, warped shelves! Since I use a lot of these, the wadding process gets expedited by rolling a coil of wadding and running the wadding along each corner and pinching off a little bit rather quickly. There’s no need nor time for carefully rolling wads. These wads are glued on as well so that they won’t fall off as I stack them into the kiln.
Michael Kline’s Wadding Recipe
Fireclay
 50%
Local Sand 25%
Alumina Hydrate 25%
Total 100%

To learn more about Michael Kline, check out his blog Sawdust and Dirt.


Learn more about salt and soda firing from Gail Nichols, one of the world’s leading experts.

“Soda, Clay and Fire is a must-read for anybody who is interested in salt or soda firing.” - Sumi von Dassow

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2 Comments

  1. Mark | September 23rd, 2009 at 2:44 pm

    for my wadding called Southern Wadding I use 1/3 grits .You can use yellow or white. It makes the wadding break apart easily
    happy firing
    Mark Issenberg

  2. Janice | September 24th, 2009 at 4:40 pm

    Mark, (from a student) what are the other 2/3?

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