M370C Casting Plainsman Clay

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Whitest firing of all mid temp bodies. More plastic than porcelains but semi-vitreous to promote stability in the kiln.

Mixing M370C for Slip Casting 

M370C has no added bentonite (unlike the regular clay which has 3%), thus its drying shrinkage is lower than M370. M370C utilizes the same #6 Tile kaolin as M370 (it is by far the most plastic kaolin available in North America). While that is great for throwing on the wheel, it is not ideal for casting (e.g. it means longer casting times). But it also offers the benefit of having plenty of leather hard strength and shrinkage so even thin walled pieces can pull themselves away from molds.

It is important to understand the principles of deflocculation, be able to measure specific gravity efficiently and have a good propeller mixer to make good casting slip. The recipe below is a guide, be ready to adjust the amount of Darvan #7 as needed (or tolerate a higher specific gravity).

Suggested recipe (yields approximately 4 litres)

Ingredient           Grams

M370C powder    5000
Water                   2100
Darvan #7                38

Mix the Darvan #7 with the water first, then add the clay to that while the mixer is running. Hold back some of the Darvan #7 for fine-tuning. Measure specific gravity by weighing, not a hydrometer. In our lab this recipe produces a slurry of 1.77 specific gravity after 1 hour of propeller mixing. Tune the amount of Darvan #7 such that the slurry gels after 30 minutes or so.

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