Colour Fastness to Sunlight
Light fastness test was carried out of both the bleached dyed and modified dyed fibres. Specimens of the fibre were attached separately on a board by a glass rod and placed on the roof of a building for exposure in the open air under the sun without any protection from weathering, but was protected form rain, dews,dust etc. The specimens were exposed under the sun for seven hours each day and continued for 250 h. After every 50 h, the fastness was assessed by comparing the change in colour of specimen with that of the standard or original.
Measurement of DL*, Da*and Db*
In addition to visual assessments, the samples were evaluated objectly by measuring the CIE Lab values (DL*, Da*and Db*) of dyed samples before and after washing using a Macbath CE-3100 spectrometer and then calculating the colour change. Illuminant D65 and 10° observer geometry were used throughout for the colour measurement.
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