Plainsman Clays | IROXB
Iron Oxide Black
Black iron oxide colours a glaze anywhere from tan, through red brown, to the darkest browns and blacks, depending on the amount. It is magnetite, so the black of the powder is not the colour that comes out of the kiln.
$0
Suggested retail price. In-store prices and availability may vary by location.
Black iron oxide is magnetite, and it is used as a colourant in glazes, slips and dark clay bodies. In an oxidising firing it starts converting to hematite within a few hundred degrees, long before a glaze melts, so the colour of the powder says nothing about the fired colour. Glazes commonly use anything from one part in a hundred for a tan up to a tenth of the recipe for the darkest browns and blacks. At that tenth the kiln atmosphere sets the surface as much as the colour. In oxidation the iron acts as a refractory and the glaze fires stiff and dry. In reduction it acts as a particularly powerful flux, so the same recipe can fire glossy and can run in different settings.
- Magnetite, and it does not stay magnetite in the kiln
- Converts to hematite long before a glaze melts, whatever colour the powder was
- One part in a hundred for a tan, up to a tenth for the darkest browns
- At a tenth, stiff and dry in oxidation, glossy and running in reduction
