Optical brighteners are colourless to weakly coloured organic compounds that, in solution or applied to a substrate, absorb ultraviolet light and re-emit most of the absorbed energy as blue-violet light between 400 and 500 nm. These compounds are included in commercial detergents formulation in order to increase whiteness and intensifying the colours. The aim of this work was to study several industrial situations related with colour changes after domestic washing. In order to achieve that, the effect of optical brighteners on white and coloured textiles was considered. The action of eight of the most known commercial detergents, on different colours, was tested. Among the selected washing agents, three of them were more specific products: a ‘colour protector’, ‘for black and dark colours’ and ‘with active oxygen’. Fabrics with and without pre-brightening were tested. In all the cases, colour fastness tests to washing (with ECE detergent and standard soaps) and to rubbing were done in order to conclude about the influence of these parameters on final results.
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