A3 Stoneware
Description
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. It is plastic and vires vitreous enough to be used as-is for the production of cone 9-10 stoneware pottery.
Process Properties
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.
Firing
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.
Glazing
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.
Physical Properties
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
Fired Shrinkage:
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
Fired Absorption:
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
