Fugitive pigments, in painting, are non-permanent
pigments (pigments that lighten in what is understood, said or defined
to be a relatively short time when exposed to light).
While most paintings are supposed to be done with
permanent pigments, painters have made work wholly or partially
with fugitive pigments for a number of reasons: ignorance as to
the permanence of the pigments, prioritising the appearance of the
colours one can get with fugitive pigments over permanence, or the
desire to have a painting change in appearance over time.