Dyeing of N-modified viscose rayon fibres with acid and metal-complex dyes

Viscose rayon N‐modified by the incorporation of polydiallyldimethyl ammonium chloride gave good dye exhaustion and colour yield on dyeing with acid or metal complex dyes. The amount of additive present in the fibre was assessed from its nitrogen content, and percentage exhaustion was found to increase with increasing quantity of additive. Changes in hue, in addition to an increase in the light fastness of deeper shades, are attributed to aggregation of dye within the fibre. The light fastness of metal complex dyes on N‐modified fibre was very good but acid dyes gave poor results. Wash fastness was improved after treating with a dye fixing agent.