Chromium Oxide is an inorganic compound used in ceramics as a green colorant. Its chemical formula is Cr2O3, and it is available in powdered form. In addition to its use as a colorant in ceramics, chromium oxide is also used in paints, inks and glasses. It is a versatile chemical, known for its use in producing green tints in glazes. When combined in proper concentrations with other chemicals, such as zinc or lead, browns and oranges may be achieved.
Chromium oxide can also be applied with brushwork as a wash on top of or underneath a glaze or used as a component in slip. It may also be mixed in directly with your clay body.
Recommended concentrations of chromium are as follows:
0.5- 2% in slips
0.25 - 2% in glazes
If chromium concentrations become too high, black will be the result.