Artificial Light–fastness Tests on Coloured Textiles

A résumé is given of the various factors which influence the rate of fading of coloured textiles by natural and artificial light, reference being made to both published and unpublished results. The importance of humidity is stressed. Two dyes of equal fastness under one set of conditions are not necessarily of equal fastness under other conditions. Consequently, it is possible for a dye to be rated differently on the British Standard (S. D. C.) system according to the conditions of testing. It is impossible to express in a single number all the information about how a dye fades. Agreement on a suitable physical method of measuring the degree of fading would help to remove some of the guesswork from present methods of colour–fastness testing.