Some Experiments on the Effect of Dye, Fibre, and Atmosphere on Light Fastness

The influence of light on dyeings on various fibres of basic dyes of different structures has been investigated in dry and moist oxygen and nitrogen. The results have been compared with those obtained under similar conditions in a normal atmosphere. It has been found that some dyes fade more rapidly in oxygen than in nitrogen. Contrary to expectation, certain dyes were found to fade much more rapidly in the nitrogen atmosphere than in the oxygen atmosphere or under normal atmospheric conditions. As expected, all the dyeings were found to fade more rapidly in a moist atmosphere. An attempt has been made to interpret the results as either an oxidation or a reduction of the dye, depending on its constitution. The water contained in the fibre is regarded as an essential component in the oxidation‐reduction process.