M340S REV is more plastic and stickier than M340S. It also works well with our L3954B engobe. In the past, many people bought the grogged version, M340GS, as insurance against bloating. This new version eliminates that need (the grog had no other benefit).
Old M340S vs new 2022 M340S REV (cone 8 down to 4)
An all-new recipe, this fires the same color as the previous M340S.
Clay bodies containing granular manganese tread a thin line between vitreous enough for strength and water tightness but being non-vitreous enough to avoid bloating (caused by the melting and gas-producing MnO particles). This body moves that line upward at least one cone from the previous M340S. If you have been firing M340S to cone 5 specifically to avoid blisters and bloating, we now recommend switching to cone 6 for M340S REV. Even at cone 6, the margin needed to avoid blisters means that unglazed or craze-glazed pieces will leak somewhat.
Toxicity: the vast majority of the manganese particles are encapsulated within the clay matrix. The tiny percentage exposed at the body surface are under the glaze. It is not the manganese particles themselves that expose at the glaze surface. Rather particle surfaces that contact the underside of the glaze bleed out into it from below, doing so as a function of the glaze thickness, opacity and melt fluidity. Thus, food contact with a glass surface having isolated manganese-pigmented regions is not at all the same thing as with raw manganese metal (or a glaze having powdered manganese as a colorant, some have up to 5%).
There should be no concerns with glazes, use the same ones you have always used.
The glaze affects the amount of specking. The inside one is a highly melt fluid lithium titanium white, it transmits and amplifies the manganese speckle. The outside one is G2926B transparent with purple stain, it subdues the speckle so much that it is almost gone.
Drying Shrinkage: 6.0-7.0% Water Content: 20.0-21.5% Drying Factor: C120
Sieve Analysis (Tyler mesh):
+48: 0.0-0.1% 48-65: 0.5-1.5 65-100: 3.0-4.0
Cone 4: 4.5-5.5% Cone 5: 3.0-4.0 Cone 6: 2.0-3.0 Cone 7: 1.0-2.0
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