Chrome yellow also called lead chrome yellow, is a yellow inorganic pigment made from adding lead nitrate or lead acetate to a solution of alkali chromate or dichromate. It is a crystalline mineral consisting of lead chromate that can vary in hue from light yellow to deep yellow, depending upon the particle size, which, in turn, depends on the conditions of precipitation. Lighter shades, such as light chrome yellow usually contain lead sulfate, or other insoluble lead salts. The middle shades are neutral lead chromate, and the orange chromes are basic lead chromate. Chrome yellow pigment consists of very fine particles that are dense and opaque.
Chrome yellows are oxidized and darkened after exposure to air for some time, which takes bad effects when using. Epsilon has developed encapsulated grade chrome yellows to avoid this problem occurred. These encapsulated varieties of chrome pigments are stable to light, high temperature, weathering and resistant to sulfur dioxide.
Common types of chrome yellow may not be used with alkali binders such as lime and water glass, because they are transformed to the red basic lead chromate. These varieties also tend to exhibit poor resistance to acids. Lead chromates can be considered compatible with all common pigments, although older references sometimes warned against mixing with chalk because of the latter's basicity. However, encapsulated varieties of lead chromate pigments are highly resistant to acids and alkalis.
Chrome yellows contain light chrome yellow, lemon chrome yellow, medium chrome yellow, orange chrome yellow, deep chrome yellow and zinc chrome yellow. Chrome yellow pigments contains lead, which is prohibited in some countries, especially Europe, Japan. The same shade of chrome yellow can be obtained by mixing cadmium yellow with enough cadmium orange.
