M340S has the same plastic and drying properties as M340. M340GS sacrifices a little drying strength to get the added texture. Since there is only 4% grog, and only a portion of that is actually coarse enough to feel, there is little gain in drying properties (many customers buy it on the misimpression that it dries better, however M340 by itself is an excellent drier, mainly because of its high dry strength). The presence the grog is an issue on functional ware because it introduces grit on rims and edges. It is also problematic in the forming process since it produces water splitting problems, most noticeable when pulling handles or throwing bellies and lips (the grog provides entrance points for the water). We recommend that you use the M340S.
The added manganese produces a fine black fired speck that usually bleeds up through glazes. These bodies MUST NOT be fired higher than cone 6 or they will blister and/or bloat. Do not trust that your electronic kiln controller is accurate, verify using cones, then manually program it to finish the firing at the temperature at which cone 6 reaches 4 oclock. If some parts of your kiln fire hotter, do not put these clays there. Overfiring will result is loss of ware.
To get the best defect-free surface please consider using a hold-rise-drop-hold firing schedule. For example, at cone 6 start with the PLC6DS schedule for porcelains. For stonewares, the best results will come with the C6DHSC schedule.
These properties are for M340GS. M340S has the same properties as M340.
Drying Shrinkage: 5.5-6.5% Water Content: 19.5-20.5% Drying Factor: C120
Sieve Analysis (Tyler mesh):
+48: 0.0-0.1% 48-65: 0.5-1.5 65-100: 1.5-2.5 100-150: 2.5-3.5
Cone 4: 3.5-4.5% Cone 5: 4.0-5.0 Cone 6: 4.5-5.5 Cone 7: 5.0-6.0
Cone 4: 6.0-7.0% Cone 5: 4.0-5.0 Cone 6: 2.5-3.5 Cone 7: 1.0-2.0
The body is Plainsman M340S. Cone 6. Left to right: G1214Z calcium matte base glaze with 6% titanium dioxide added. GR6-A Ravenscrag base with 10% zircopax (zircon). G2926B glossy transparent base with 10% zircon. G2934Y silky magnesia matte base with 10% zircon.
Safety Data SheetClick here for web view.
|Plainsman Clays Ltd.|
702 Wood Street, Medicine Hat, Alberta T1A 1E9
Phone: 403-527-8535 FAX:403-527-7508