Light destroys many colours at a rate which can be predicted by the ISO light fastness scale and by other relevant light fastness datings. The data on which the ratings are based are examined for visible ultraviolet light. The forms of damage, the wavelenth dependence and the rates of damage are presented for both these sources of light. The patterns of damage exhibited by paint, paper textiles, feathers, hair, insects glass and minerals are summarised. The author concludes that every light source in museums should be filtered.