B Stoneware


B clay is probably our most balanced material (in that you can simply add water and make vitreous cone 6-8 stoneware from the pure material). It's quarry seam is about 6 feet thick (parts of the seam are super fine and completely vitrify at cone 6). It is exceptionally smooth and slick having moderate plasticity. This material is fine enough that a simple slaking process on the dry lumps will create a slurry of which +99% passes a 200 mesh screen!

B clay is incrediblely smooth and fine grained. This mug is made from unprocessed material (a selected lump from the center of the seam), there is not a single grain of sand it in! It is plastic enough to throw thin walled pieces.

Stock pile of B at the Plainsman plant.

A 10kg lump of B clay at the quarry (from the center section of the seam). It is quite damp and amazingly dense and heavy. It is layered, somewhat like the rings on a tree, the lines run horizontal in the clay bed. In the lab its splits apart in layers (revealing carbon stringers).

B clay 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 has built-in feldspar, it is naturally vitreous at stoneware temperatures (around 0.5% at cone 10R). 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 in the upper section of the seam).

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 the natural fine grain and minimal particulate impurities.

Physical Properties

Drying Shrinkage: 5.5-6.5%
 Drying Factor: C120-

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: 5.5%
  Cone 10: 6.0%
 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

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