I have not found a ^6 Flameware Clay Recipe so I'm trying to adjust ^9 flameware recipes. Ron Propst's flameware clay body recipe (below) has a thermal expansion of 5.25

My initial thoughts are:

1.) replace the 10% Custer Feldspar with 10% Talc, resulting in an expansion of 4.82 according to Insight.

2.) add 5%? Lithium Carbonate or Lithium Fluoride with a thermal expansion of 5.28 - closer to the original. Or does this increase Lithium enough to present a leeching problem?

3.) would I end up with a stronger fired body if I replace some or all of the AP Green Fire Clay with Kyanite? With Kyanite the expansion is 4.88 for option 1, and 5.33 for option 2, but those Kyanite needles should make the ware stronger.

4.) I've also noticed that the original flameware clay body is very spongey like a marshmallow, yet not very plastic. Is this just typical of a body with a high percentage of spodumene? I used 3% VeeGum Bentonite rather than 2% Bentonite and 1% Macaloid, but I'd be surprised if that made a large difference.

5.) Of course the ^6 glaze recipe will have to have a thermal expansion just a little higher than the clay, but I'm more comfortable with glaze chemistry.




Flameware Clay Body - Ron Propst
Low 5.25 Thermal-Expansion clay body for stove-top cooking pots

Materials                Amt     
Spodumene        30.000     29.13%
APG Fireclay       30.000     29.13%
Ball Clay             20.000     19.42%
Pyrophyllite         10.000       9.71%
Custer Feldspar   10.000       9.71%
Bentonite              2.000       1.94%
Macaloid               1.000       0.97%


Unity Formula
CaO     0.02
Li2O     0.30
MgO     0.04
K2O     0.05
Na2O     0.04
(KNaO)     0.09
TiO2     0.04
Al2O3     1.00
SiO2     3.84
Fe2O3     0.02


Si:Al Ratio

Calculated Expansion 5.25

Robbie Lobel Flameware Casserole Dish


Views: 3276

Reply to This

Replies to This Discussion

I just received some bisqued samples of my batch of Ron Propst's ^9 flameware.

It's very lightweight and porous, like the firebrick used in electric kilns, but far more durable. It's very difficult to break one of these bisqued tiles.

I wonder if some Darvan might deflocculate the clay body and make it denser and not so spongey. Bentonites add plasticity to clay bodies, but maybe 3% VeeGum left the clay too flocculated.

Is this tile Ron Propst's ^9 flameware or your modification? Did you replace the AP Green with Kyanite?

I have made many cooking pots with very porous low fire earthenware, and they are very wonderful to cook in but not the most durable. They are cheap to make and cheap to fire however.

Right now I am developing a castable to use in a bread oven kit. What I need is something that has very low dry & fired shrinkage & can take the heat shock, plus hold as much heat as possible. I'm getting close with a talc body fired to ^ 1.

Harold - The post you're replying to was the start of a long process. Ron Roy referred me to George Tsitsas of Marrowstone Pottery.

They have this PDF file (link below) on their website called "A Discussion of Flameware".



In order to survive rapid cooling and expansion, the ceramic body has to have a very low COE (expansion rate) which requires a suitable Cone 6 flux lithium, or similar low-expansion flux. As a result, normal glazes will just shiver off the body, so you have to develop lithium glazes which are similar to the clay body. If you like clay chemistry, you'll have a lot of fun developing your clay body and glazes.

The three or four potters best known for "flameware" have each created their own unique solution to this problem, and more or less jealously guard their "trade secrets".

I've promised George Tsitsas I won't pass on a lot of the knowledge he has gained through long experience.  But I can tell you he is adamant that the key to developing your own low-expansion clay body is the use of a dilatometer to measure the COE of your clay samples, as small changes can create a large change in COE.  I think Ron Roy still tests fired clay bars in his dilatometer for a fee, and there are a number of labs which do so as well.

An Orton Dilatometer  (used to measure the expansion of a bar of fired ceramic as it is heated)

If there is one primary secret, it is creating a flameware body which has plasticity without excess flocculation which causes the body to have an undesirable marshmallow texture, which I displayed in the posts above last year. Since the plasticity typically needs to be provided by Macloid or similar charged clays, one important key is the use Distilled or Reverse Osmosis water to mix the ingredients. The less fewer free calcium and magnesium ions you have in the water, the better the chance that your flameware body will have a clay-like texture which can be thrown or formed in a traditional manner.

The PDF file puts you on the right track.

George Tsitsas testing a glazed bowl.   http://www.youtube.com/watch?v=WFwZ1x6JoVs

Reply to Discussion



  • Add Videos
  • View All

Use These Links to Support Us

Low cost flat lapping disc can be used on you potters wheel if you, drill bat pin holes in it, and provide a trickle of water to cool it. At amazon.com, 120 grit for aggressive material removal. Click the image to purchase 

Members have had great things to say about John Britt's new book, Mid-Range Glazes. Click the image to buy from Amazon.com

Purchase Glazes Cone 6 by Michael Bailey, The Potters Book of Glaze Recipes by Emmanuel Cooper, or Making Marks by Robin Hopper, all available at amazon.comMastering Cone 6 Glazes by John Hesselberth & Ron Roy is now out of print.

Harbor Freight is a great place to find unbeatable prices for better HVLP spray guns with stainless steel parts and serviceable economy models, as well as detail guns, all tested by our members for spraying glazes, as well as compressors to power the guns. As yet no one has tested and commented on the remarkably inexpensive air brushes at harbor freight.

The critter siphon gun is a spray alternative that is well liked by some of our members, and is available at amazon.

Amazon is also a competitive source for photo light tents for shooting professional quality pictures of your work. They also have the EZ Cube brand favored by several of our members. You might also want to purchase the book Photographing Arts, Crafts and Collectibles . . .

If you are up to creating videos of your work or techniques you might want to invest in a flip video camera

Following are a few scales useful for potters. Your final price could be less or more - things change.

American Weigh Black Blade Digital Scale, 1000g X 0.1g $11.08 

For the non-digitally inclined the old standard Ohaus Triple Pro Mechanical Triple Beam Balance, 2610g x 0.1g, with Tare $169.00

And finally a low cost clone of the OHaus. The Adam Equipment TBB2610T Triple Beam Mechanical Balance With Tare Beam $99.62

ebay is a great alternative for many tools and the equipment used in the ceramics studio - kilns, wheels, extruders, slab rollers are often listed there both new and used.

Tips for Members

If you just want to spout off, it is best accomplished as a blog posting. If you want to get more guidance and ideas from other members, ask a question as a new discussion topic. In the upper right corner of the lists for both types of posting, you will find an "+Add " button. Clicking it will open an editor where you create your posting. 4/16/2014

© 2020   Created by George Lewter.   Powered by

Badges  |  Report an Issue  |  Terms of Service