The Roffey family by Joshua Reynolds

Conservation of pigment......

Some paintings have to be kept in semi-darkness to stop the pigment in the paint from fading any further. Whether colours fade or not depends on where they come from.  Some pigments are more sensitive to sunlight than others.

The faces of the people in this picture appear very pale. The pink glaze which the artist used to tint the skin has faded due to exposure to ultra-violet light.