3D Silty Clay


Medium to high temperature, silty, low plasticity, light tan firing, very clean native stoneware.

3D is mined from our Ravenscrag, Sask. quarry. It is a silty material containing natural feldspar that vitrifies it fully by cone 10. Mechanically, it is one of the cleanest (low in particulates of iron and light burning) and most consistent raw materials we have. In the raw lump form, 3D clay weathers and slakes very readily. 3D is suitable as a filler and body base and has excellent potential in dry press and tile bodies. In plastic bodies it responds very well to bentonite additions.

Process Properties

3D can act as a body base. For example, 95% 3D and 5% bentonite produces a body with very good plastic workability that fires very pinhole and glaze imperfection free. By itself, it dust-presses well (for tile manufacture). It works well with additions of low temperature iron-bearing clays (like Redart) and responds well to feldspar or minor frit additions to achieve maturity at lower temperatures.

3D is also a alternative to sand or grog as an addition to bodies where plasticity needs to be cut and drying properties improved. Like sand, significant additions of 3D without corresponding impermeable plastic clays to balance it can make a body susceptible to water splitting during forming processes (and generate more slip during throwing). Additions of bentonite (if it can be tolerated) will improve both situations.

3D opens up the internal pore structure in the dry body matrix and this will help channel water out during drying.


3D fired test bars from cone 10 down to 5 oxidation and cone 10 reduction (top).

3D vitrifies around cone 10 (to 0.5% porosity). In oxidation it burns buff increasing to grey buff as temperature increases to cone 10. It fires with less reduction speckle and to a ligher buff color than any other native naturally-fluxed material we have.


Because 3D is low in gas-producing particles, glazes fire with fewer surface defects (e.g. pinholes, blisters). In fact, even the unground, slaked material produces clean glaze surfaces. This is a key advantage of this material for tile manufacture, minimal processing is needed.

Physical Properties

 Drying Shrinkage: 4.5-5.5%
 Drying Factor: B110

Sieve Analysis (Tyler mesh):

     +48     (300 microns): 0.0-0.6%
   48-65 (300-210 microns): 0.5-1.0
  65-100 (210-149 microns): 0.5-1.5
 100-150 (149-106 microns): 1.0-2.5
 150-200  (106-75 microns): 3.5-5.5
 200-325   (75-45 microns): 5.0-8.0

Fired Shrinkage:

   Cone 6: 5.5-6.5%
   Cone 8: 5.5-6.5
  Cone 10: 6.5-7.5
 Cone 10R: 6.5-7.5

Fired Absorption:

   Cone 6: 3.5-4.5%
   Cone 8: 2.0-3.0
  Cone 10: 0.3-0.9
 Cone 10R: 0.2-0.7

Chemical Analysis

 BaO       0.4
 CaO       0.2
 K2O       2.6
 MgO       0.5
 Na2O      0.1
 TiO2      0.6
 Al2O3    16.3
 P2O5      0.0
 SiO2     71.5
 Fe2O3     1.1
 MnO       0.0
 LOI       6.6%

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