M2 Red Clay


Medium maturing high iron medium plasticity smooth stoneware.

The raw clay before it is ground.

M2 is our most important iron-bearing material. It works so well because of its consistency, the fact that it does not increase body plasticity, its broad firing range, fine particle size, lack of soluble salts, purity (low particulate iron impurities) and its linear (rather than volatile) maturing curve. We have a number of customers that use M2 pure (without any additions).

Process Properties

This is not as plastic as a typical pottery body, although it can be formed without problems. In recipes it needs the help of ball clay and/or bentonite. A typical vitreous cone 6 recipe might be 80% M2 and 20% ball clay. Or 87% M2, 10% silica, 3% bentonite.


M2 fired bars (left) vs. M350. M2 fired at cone 6, 4, 2, 02, 04 (top to bottom). M350 from cone 8 down to 4 (top to bottom).

Used pure, M2 is over fired by cone 6. This is ideal since adding ball clays (which are refractory) moves both the maturity and plasticity in the right direction. For the darkest colored bodies, M2 needs to be kept at a high percentage (so the lower ball clay will necesitate a little bentonite for plasticity).

Physical Properties

 Drying Shrinkage: 6.0-7.0%
 Drying Factor: C120

Sieve Analysis (Tyler mesh):

     +48     (300 microns): 0.0-0.6%
   48-65 (300-210 microns): 0.4-0.8
  65-100 (210-149 microns): 2.5-3.5
 100-150 (149-106 microns): 2.0-3.0
 150-200  (106-75 microns): 5.5-7.5
 200-325   (75-45 microns): 7.0-10.0

Fired Shrinkage:

   Cone 2: 4.0-5.0%
   Cone 4: 4.5-5.5
  Cone 6: Overfired

Fired Absorption:

   Cone 2: 3.0-4.0%
   Cone 4: 1.0-2.0
  Cone 6: Overfired

Chemical Analysis

 CaO       0.3
 K2O       2.7
 MgO       1.0
 Na2O      0.1
 TiO2      0.7
 Al2O3    13.5
 P2O5      0.3
 SiO2     69.4
 Fe2O3     6.1
 LOI       6.0%

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
Email: plainsman@telus.net