Depending on the use, ceramic pigments may be used straight and just mixed with water, but they are more commonly added as colorants in clay bodies and glazes. Some ceramic pigments are specifically formulated for clay bodies while some are not suitable at all. When used in clay, ceramic pigments are usually used in engobes and slips as a coating for clay rather than pigmenting the entire body. The exception to this would be using stains to tint porcelain for neriage work.
Use in concentrations of 10–15% in clay, using more or less depending on the intensity needed. Add the ceramic pigment to the slip and sieve through a 120x mesh screen to ensure adequate dispersion.
Ceramic pigments can be used in underglazes for brushing onto greenware or bisque. If used only with water as a medium, some glazes may crawl, so for best results, mix the stains with a frit (for example, Ferro frit 3124). Begin with a mix of 85 frit/15 ceramic pigment and test. Transparent gloss glazes applied over the top will heighten the intensity of the colors.
When using ceramic pigments in glazes, usually in concentrations of 1–10%, a little more care must be taken because some ceramic pigment systems react with materials in a glaze. Some ceramic pigments are affected by the presence, or lack of, boron, zinc, calcium, and magnesia. Manufacturers provide information on specific reactions. While most ceramic pigments can be used in both oxidation and reduction atmospheres, some are limited to certain maximum temperatures. Again, this information is available from manufacturer websites.
To achieve a wider palette, most ceramic pigments can be mixed to achieve even more colors. The exception is that black ceramic pigments cannot be used to obtain shades of gray because blacks are made from a combination of several metallic oxides. If low percentages are used, the final color is affected by the predominant oxide in the black ceramic pigment.
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