A further study of dye batch variation in textile and carpet fibres.

Four sets of acrylic fibre samples were obtained from a company that dyes fabrics for the fashion industry. Between seven and ten different batches of fibres constituted each set. Comparison microscopy, visible and UV range microspectrophotometry and thin layer chromatography (TLC) were used to compare the dyes on each batch of fibres within the sets. Only one of the four sets exhibited variation within the batches. The differences were seen when both microscopical and analytical techniques were used. In addition, two further sets of samples had been obtained from a company that produces carpets for the car industry. The first set consisted of 26 batches of acid dyed orange nylon fibres. The second consisted of 21 batches of acid dyed mustard coloured nylon and direct dyed brown viscose fibres blended together. When the first set was viewed under UV light one batch had more pale orange fibres present and they fluoresced more brightly than the other fibres. This could be due to the blending with a different dye batch of fibre or due to poor dye uptake--the latter being more likely. When tested using visible and UV range microspectrophotometry and TLC, further dye batch variation was not detected. The second set was examined after separating the nylon and viscose fibres from each other. The nylon fibres were indistinguishable when a range of microscopical and analytical techniques were employed; however, the viscose fibres showed dye batch variation when TLC was used.