Chrome Oxide- Green (Sold in .25 Units)

Chrome oxide is a very refractory ceramic colorant (even a 50% mix with a high borax frit will not even begin to melt it in a crucible). Chrome oxide is the only stable oxide of the metal chromium. It is a bright to dark green crystalline powder insoluble in alkalis and acids. As with other powerful coloring agents, chrome must be milled fine enough to eliminate specking in glass or glaze.

Chromium is a 'fast' colorant, meaning can produce strong green colors under all furnace conditions, slow or fast, reducing or oxidizing. It is also a flat colorant (due to its refractory nature), it usually produces an army helmet opaque green. It is powerful, typically only 2% will produce a dark color. It cannot be used to make a metallic glaze.

Chrome oxide is usually employed in raw glazes whereas potassium dichromate is used in fritted glazes.

Since Cr₂O₃ becomes 2CrO₃, oxygen is captured from the surroundings, thus the percentage (or conversion factor) is greater than 100.

Chrome is refractory on its own (as are chrome containing materials like Chromite). It is used to make refractories. One supplier, termorefractories.com, says: "Chrome magnesite refractory bricks are produced from sintered magnesia and chrome ore that has refractory level. Content of chrome-magnesite refractory bricks is generally, 15-35% Cr₂O₃ and 42-50% MgO whereas magnesite-chromite refractories contain at least 60% MgO and 8-18% Cr₂O₃. Bonding space between refractory grains is done with silicate."