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Plainsman Clays | COFFEE
Coffee Mid Fire Clay
$67.58 / 20 kg (44 lb) Pugged
$0
Suggested retail price. In-store prices and availability may vary by location.
Mid fired, Dark brown burning, Smooth, Plastic, Functional, Throwing clay body
Specifications
Type
Cone 6 medium temperature stoneware · dark brown burning · functional
Texture
Smooth and plastic, and easy to throw
Usage
Throwing · functional tableware · dark fired colour without slips or stains
Temperature
Cone 5 · 6 · 7 – like all of our medium temperature clay bodies, Coffee is designed to fire at cone 6 (1222 °C / 2232 °F). Cone 6 is a hard ceiling: above it the body bloats badly.
Colour
Dark brown · the colour develops through cone 5 to 6
Shrinkage
Dry 7.3–8.0% · fired 6.5–7.3% at cone 5, 7.0–7.8% at cone 6, 7.5–8.3% at cone 7
Absorption
Cone 5 2.8–3.2% · cone 6 2.2–2.5% · cone 7 1.0–2.3%
Every figure is a measured range from the Plainsman lab, not a single nominal number. Cone equivalents are Orton self-supporting cones at 108 °F/hr.
Description
Coffee is a dark brown burning stoneware for functional work at cone 6. The colour is in the body itself, derived from burnt umber – a calcined natural clay – rather than applied as a slip or stain, so it runs all the way through the piece.
It is smooth and plastic, throws easily, generates plenty of slip on the wheel, and stays workable even when soft.
Firing to cone 6 is a firm limit rather than a preference. Beyond cone 6, the umber begins to break down and the body bloats badly, so this is not a clay to push to cone 7.
Working properties
- It is smooth and plastic, easy to throw, and generates plenty of slip as you work.
- It stays workable when soft, so it is forgiving of a wetter consistency than some bodies.
- Coffee contains manganese. Vent your kiln when firing it, and do not work around fumes.
Fired colour & cone behaviour
- Dark brown, with the colour developing through cone 5 to cone 6.
- Do not fire above cone 6. The umber starts to decompose past that point and the body bloats badly.
- As the firing approaches cone 6, the umber gives off a significant amount of gas. That gas can puff up a glaze and leave an orange-peel surface, so a drop-and-hold or slow cooling at the top of the firing will produce a cleaner result.
Glazes & glaze fit
- The colourants in the body bleed into glazes, so a glaze will not look the same over Coffee as it does over a light-burning clay. A glaze that works on M340 may not work here.
- Clear glazes are the most likely to cause problems, often becoming cloudy with fine bubbles. Slip-based glazes perform well on this body.
- For functional ware, confirm glaze fit with a boiling-water-to-ice-water immersion test. Ware that looks craze-free out of the kiln can still craze later, so test rather than assume.
- Coffee is relatively high in iron, so pieces will heat up in a microwave. Test any piece intended for microwave use.
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