Thursday, October 08, 2009

Asian Coil Throwing Clay Recipe

I am looking for an "Asian Coil Throwing Clay Recipe". Daniel Johnston calls this big pot clay. What is needed seems to be a sticky clay full of temper.

We have used standard stoneware recipes with added grog. While they work, they do not have enough grog usually and if they do they are not sticky enough. I am considering increasing the ball clay, adding bentonite or maybe even an organic gum.

My experience is in Dankwean Thailand. There the clay comes from under the rice fields. It is tropical, it stays wet or at least damp probably all year as it is down a meter. Like most other clays used in Thailand for big pots if fires to a high temperature and is pretty dark.

Here is what we have been using roughly.

100 Fireclay (usually mixed between Hawthorne Bond and Greenstripe)
50 Ball Clay (KT1-4, OM4 or CandC)
15 Custer Feldspar
35-50 mixed Oklahoma #1 sand and grog.

It is more plastic than we need but not sticky enough.

Here is what I am considering testing
50 Sand and grog
50 Ball
50 Hawthorne
10 Feldspar

2. 50 Newman Red
25 Fire Clay
25 Ball Clay
25 Kaolin
50 Sand

The Newman clay seems to be able to replace feldspar.

3. Sand 75
Ball Clay 50
Kaolin 25
Haw Bond 25
bentonite 3

4. Newman Red 25
Hawthorne bond 50
Kaolin 50
Sand 75
Bentonite 5

Some considerations are that my graduate students have already been using LPC1 above. Consequently just as traditional potters, the technique is altered to fit the materials. Now it is time for the materials to alter to fit the technique. These tests above may be too big steps.

In Thailand, as would be expected, the shorter the clay body the less the forms are dependent on stretching. Even where stretching of the initial form is substantive it is more often accomplished with a paddle and anvil.

In Dankwean potters are stretching pots more and more. In potteries where this seems most evident the clay being used is more highly processed and probably blended. Ajahn Pit's pottery is aging their clay significantly. 20 years ago it was used relatively fresh.

Ratchaburi water jars are highly stretched in the belly through paddling. Their clay is pretty plastic, as is the clay of Pakred. Traditionally thrown Pakred pots are also stretched far and the clay is relatively co-operative in this regard. I have not had a long visit to either pottery in quite a long time, I expect the clay has changed some.

I have not been in Baan Phon Bok Thailand in 20 years. This is where Daniel Johnston worked. I do have some big pot clay from there that Daniel gave me. It has a nice wide spread of temper sizes. Daniels clay also has a wide variety of grit sizes (mostly quartz) . As I think about this I am considering making my own grog as they do in Baan Maaw in Mahasarakham by making bowling balls of clay and rice hulls, firing them to around 1200 degrees and crushing them. They can (probably) be made with sawdust instead of rice hulls, but then you must wash all the soluble alkali out of them.

If Y'all have any ideas I would love to hear them.