NATURAL EARTHS: Umber, burnt umber, sienna, burnt sienna, sinopia, caput mortuum, goethite, iron oxide, iron(III) oxide, ochre, Venetian red, and several other named colors are all various shades of iron oxide. The differences in color is due to how hydrated the earth may be, or if it was heated, or how light is diffracted through the particle size of the oxide. Earth colors are not consistent, even when in the same mine, so each order of the same color may be a slightly different shade. These strong, non-toxic, permanent pigments are compatible with most mediums.
DYE EXTRACTS: Dye extracts are natural dyes that have been processed with alum then dried into concentrated pow-ders. A little goes a long way. They can be used for immersion dyeing as well as for pigments, or for hand-painting fabric, along with natural oxides. Dyes are more fugitive than earth oxides but with care, they can last a long time. Full instruc-tions included with each order.
MIXED or ENHANCED: These two words as well as “mineral colors” and sometimes “oxides” can mean that two or more colors were combined to enhance the original color or to create a third color. This practice has historic precedence; Cennini noted that some natural colors need artificial help. “Earth oxide” is a modern merchandising term for mineral-colored earths/clays that may or may not be mixed or enhanced for more vibrant colors.