Fugitive pigment
Fugitive pigments are impermanent pigments that lighten, darken, or otherwise change in appearance or physicality over time when exposed to certain environmental conditions, such as light or pollution. Fugitive pigments are present in types of paint, markers, inks etc., which are used for temporary applications. Fugitive inks which washed away when soaked in water were sometimes used deliberately to prevent postage stamps being removed from envelopes by soaking, and reused (e.g., the Queen Victoria Lilac and Green Issue).
While permanent pigments are usually used for paintings, painters have made work wholly or partially with fugitive pigments for a number of reasons: ignorance regarding the volatility of the pigments; being more concerned with the appearance of colors available only with fugitive pigments than with permanence; or the desire to have a painting change in appearance over time.
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