High temperature, smooth, medium plastic, vitreous, buff-white firing, clean native stoneware. A3 clay is not a blend of materials, it is mined from our Ravenscrag, Sask. quarry from a single clay seam. It provides the basis for most of our high-fire stoneware bodies. Its plasticity is slight greater than a standard clays. It can be used as-is for the production of cone 8-9 stoneware pottery. The seam of raw clay is grey in color.
A3 clay is very smooth and slick and its plasticity is a little higher than other clays. 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. From a workability point of view A3 clay is suitable as a major ingredient in stoneware clay bodies. It is balanced enough that it can actually be the only ingredient in a cone 10 buffstone storeware.
Although A3 clay is very fine, it does not disperse or deflocculate. Soluble materials within the clay impede the action of normal deflocculants resulting in gelling of the slurry.
A3 fired bars from cone 10 oxidation down to 6 (left) vs. B Clay from cone 10R and 10 down to 7 (right). B Clay is the base for Midstone, it is more vitreous than A3.
Fired test bars of A3 (left) vs. Plainsman Fireclay (right); top bar is cone 10R, below cone 10 down to cone 7.
Since A3 clay is naturally vitreous (but not overly so) at cone 10 it is not necessary to add feldspar to flux it. Midstone can be added to improve vitrification.
A3 stoneware is high in quartz and not difficult to fit glazes to, especially at higher temperatures. Its very fine grain and minimal impurities mean that it will present few problems with regard to glaze pinholing.
Drying Shrinkage: 1995 6.3-7.3%, 1999 6.0-7.0 Dry Strength: n/a Water Content: 22.0-23.0 Drying Factor: C130 Dry Density: n/a
Sieve Analysis (Tyler mesh):
+48 (300 microns): 0-0.1% 48-65 (300-210 microns): 0.0-0.3 65-100 (210-149 microns): 0.2-0.8 100-150 (149-106 microns): 1.0-2.0 150-200 (106-75 microns): 1.0-3.0 200-325 (75-45 microns): 3.0-8.0
1995 1999 Cone 6: 5.0-6.0% 4.0-5.0% Cone 8: 5.5-6.5 4.5-5.5 Cone 10: 6.0-7.0 5.5-6.0 Cone 10R: 6.0-7.0 6.0-7.0
1995 1999 Cone 6: 1.0-2.0% 4.0-5.0% Cone 8: 0.5-1.5 2.5-3.5 Cone 10: 0.2-0.8 1.5-2.5 Cone 10R: 0.5-1.5 1.0-2.0
BaO 0.4 CaO 0.2 K2O 2.0 MgO 0.7 Na2O 0.1 TiO2 0.6 Al2O3 19.4 P2O5 0.0 SiO2 66.5 Fe2O3 1.5 MnO 0.0 LOI 8.4%
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|Plainsman Clays Ltd.|
702 Wood Street, Medicine Hat, Alberta T1A 1E9
Phone: 403-527-8535 FAX:403-527-7508