A type of inorganic color pigment used in printing inks derived primarily from lead chromate (chemical formula PbCrO4). Chrome Yellows comprise several shades, ranging from primrose to orange. Chrome Yellows have a higher specific gravity than do other pigments, resulting in lower pigment volume than can be obtained with other materials. Extenders are often added to Chrome Yellows, especially to the bulkier green shades. Chrome-based pigments possess moderate lightfastness (although some darken on exposure to light, or on contact with sulfur gases), and are highly opaque. They hold up well when mixed with solvent- and oil-based vehicles, and are resistant to acids, soaps, and waxes, but are susceptible to decomposition in the presence of a strongly alkaline substance. When exposed to heat, Chrome Yellows turn reddish in color, but return to their original shade when the heat is removed. Chrome Yellows had been used as the first-down color in process color printing, and are suitable for use in all types of inks, but the increased undesirability of lead-based inks has diminished their popularity and use.
Chrome Yellows can be mixed with Iron Blues to produce Chrome Green. Other chromes, derived from various shades of Chrome Yellows, include Chrome Orange and Molybdate Orange. (See also Inorganic Color Pigments.)
('CI Pigment Yellow 34 Nos. 77600 and 77603'.)