Studies in Wool Yellowing

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Abstract
Fluorescence measurements have been made on wool samples which have been treated with the fluorescent brightening agent Leucophor PAF. Several parameters have been varied, such as the effect of prebleaching the wool and of treatments with aluminum sul fate and/or thiourea-formaldehyde. Aluminum sulfate pretreatment of wool led to increased fluorescence. Thiourea- formaldehyde aftertreatment resulted in quenching of the fluorescence for bleached samples containing low concentrations of brightener but enhancement of fluorescence for samples treated with high concentrations of fluorescent brightening agent. Decreases in fluorescence occurred on both wet and dry irradiation, the decrease being more pronounced on wet irradiation. The correlation with previous work based on yellowness index and visual assessments are discussed, as are the implications for the production of white fabric stable to sunlight exposure.