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One area of concern is that the grog will tend to produce rough glaze surfaces on areas where the glaze is thin (i.e. the lips of functional ware). Thus occurs as sharp grog particles expose themselves above the glaze surface as the latter thins during firing. Avoid sponging rims on dry or leather hard ware since this tends to remove fines and expose grog particles even more.
M325 fires to a yellowish buff color from cone 3 to 4, then as temperature reaches cone 5, the effect changes toward grey buff. From cone 6 to 7 it is a stone-grey. At cone 8 it is unstable; sometimes it will produce a vitrified material, other times it will begin to bloat. If you are not using M325 primarily for its fired color, you might try M340 instead. M340 is smoother and thus better for the production of functional ware.
M325 requires no special treatment for firing. It is the material of choice only if you require the dark yellow-buff fired color. Otherwise we recommend you use M340 for functional ware.
M325 should work with the same glazes as most of our other middle temperature bodies. However, since it fires to a darker color you might find that certain colored glazes or underglaze decorations might be subdued. This happens because the iron in the M325 muddies the purity of other coloring oxides. If this happens use a white slip on the clay surface or try another light firing clay body.
Drying Shrinkage: 6.0-7.0% Water Content: 20.5-21.5% Drying Factor: C120-C130 Dry Density: n/a
+48: 0.1-0.5% 48-65: 2.0-3.0 65-100: 2.5-4.5 100-150: 2.0-4.0 150-200: 4.0-6.0 200-325: 7.0-10.0
Cone 4: 3.0-4.0% Cone 5: 4.0-5.0 Cone 6: 4.5-5.5 Cone 7: 4.5-5.5
Cone 4: 5.0-7.0% Cone 5: 3.5-4.5 Cone 6: 2.5-3.5 Cone 7: 1.5-2.5
BaO 0.3 CaO 0.2 K2O 2.3 MgO 0.9 Na2O 0.2 TiO2 0.6 Al2O3 18.2 P2O5 0.0 SiO2 68.6 Fe2O3 1.5 MnO 0.0 LOI 7.2%
|Plainsman Clays Ltd.
702 Wood Street, Medicine Hat, Alberta T1A 1E9
Phone: 403-527-8535 FAX: 403-527-7508