Cobalt
Chrome
"Chrome is a rather versatile and fickle colorant," (Chappell). Chrome oxide (Cr2O3) is commonly used for achieving greens. However, in the presence of zinc, chrome can produce brown. Glazes with tin oxide present will often blush to pink if fumed with chrome or if chrome is present in the glaze with the tin, often intense pinks occur. If fired above cone 6, chrome will fume and become a gas in the kiln. Common saturation percentages for chrome at low saturation range from (.25 to .5%) and at higher percentages from (1 to 2%). Chrome is a refractory.Red Iron
Copper
Copper's carbonate form (CuCO3) is commonly used to produce greens, turquoise, and copper reds. If need be, copper oxide (CuO) can be substituted but has a larger particle size and glazes should be adjusted to generally half the amount called for. In barium based glazes greenish blues often result from copper. AlkalineReferences
*''Clay and Glazes: Revised edition''. Chappell, James. Watson-Guptill Publications, New York. 1991. *''Glazes for the Craft Potter''. Fraser, Harry. Watson Guptill Publications, New York. 1974. *''Clay and Glaze for the Potter''. Rhodes, Daniel. Krause Publications. 2000. Expanded and Revised by Robin Hopper. Ceramic materials