B Stoneware


B clay is probably our most balanced material (in that you can simply add water and make vitreous cone 10 stoneware from pure B clay). However, in the interests of long-term body consistency, we blend it with other materials. It is very smooth and slick and its plasticity is slightly lower than a typical pottery wheel throwing body. This material is fine enough that a simple slaking process on the dry lumps will create a slurry of which +90% passes a 325 mesh screen.

B clay is thus suitable as a major ingredient in stoneware clay bodies. Again, if non-plastics like feldspar and silica are present in your recipe, you will have to counter these with plastic materials like ball clay and bentonite to maintain workability.

Stock piles of B and A3 at the Plainsman plant. A3 is more plastic but not quite as pure and white as B. Many of our clay bodies use a blend of these two materials as a base. These have some moisture so the color is darker than when they are dry.

B-Clay has the whitest color of our natively mined materials. When dry it is quite white, but when damp the color is darker.

Although B clay is very fine, it cannot be effectively deflocculated. Soluble materials within the clay impede the action of normal deflocculants resulting in gelling of the slurry.


B Clay test bars fired at cone 6, 8, 9, 10 and 10 reduction (bottom to top).

Plainsman B vs. A3 fired bars. Top bars are cone 10 reduction, downward are cone 10, 9 and 8 oxidation.

Since B clay is naturally vitreous at stoneware temperatures (around 0.5% at cone 10R) it is not necessary to add feldspar to flux it. This makes it possible to create bodies with higher clay content and better workability. It does fire with some iron specks in reduction at cone 10 (due to natural iron pyrite particles).

Plainsman adds a small amount of barium carbonate to the standard retail product (about .5%) to precipitate natural soluble salts present in the material. This can be left out on custom orders.

Glaze Recipes

Since B clay has siqnificant natural raw quartz content it is not difficult to fit stoneware glazes to it, especially at higher temperatures. It will present few problems with regard to glaze pinholing due to its natural very fine grain and minimal particulate impurities.

Physical Properties

Drying Shrinkage (+/- 0.5): 6.0% @ ?
 Drying Factor: C120-
 Dry Density: 2.0

Sieve Analysis (Tyler mesh):

     +48     (300 microns): 0-0.1%
   48-65 (300-210 microns): 0.0-0.3
  65-100 (210-149 microns): 0.5-1.0
 100-150 (149-106 microns): 0.5-1.5
 150-200  (106-75 microns): 2.5-4.0

Fired Shrinkage (+/- 0.5):

   Cone 6: 5.0%
   Cone 8: 5.8%
  Cone 10: 6.2%
 Cone 10R: 6.5%

Fired Absorption:

   Cone 6: 3.5%
   Cone 8: 1.5%
  Cone 10: 1.0%
 Cone 10R: 0.5%

Chemical Analysis

 BaO       0.4
 CaO       0.2
 K2O       2.2
 MgO       0.5
 Na2O      0.1
 TiO2      0.6
 Al2O3    15.6
 P2O5      0.0
 SiO2     72.7
 Fe2O3     1.2
 MnO       0.0
 LOI       6.5%

Safety Data Sheet

Click here for web view.

Logo Plainsman Clays Ltd.
702 Wood Street, Medicine Hat, Alberta T1A 1E9
Phone: 403-527-8535 FAX:403-527-7508