Natural dyeing of plasma treated wool with avocado seed extract and use of tartaric acid as bio-mordant

In this study, surface modification of wool fabrics by oxygen plasma was carried out to enhance colour, dyeability and fastness properties. Avocado (Persea americana) seed was selected as the natural dye source, plasma activated wool samples were dyed with the extracted colourant and tartaric acid (10% and 20% owf) was used for simultaneous mordanting. All samples exhibited very good washing and dry rubbing fastness grades. It was observed that plasma treated samples have darker and more saturated colours with a persistent hue and increased wet rubbing fastness grades. Applying plasma treatment and using tartaric acid as bio-mordant provided a noticeable increase in chroma and colour strength, and a slight improvement in fastness to light. Effect of pH of the dye bath on dyeability and the bio-mordant role of tartaric acid were also investigated for four mordant concentrations (2%, 5%, 10% and 20% owf), and it was detected that using 5% owf or higher concentrations of tartaric acid provided different colour characteristics and dyeability when compared to the dye solutions prepared with inorganic acid. Based on findings of the study, it was concluded that modifying the fabric surface by oxygen plasma can be used to enhance the dyeing performance without causing a major change in the characteristic hue of the colourant extracted from avocado seeds. The use of tartaric acid - solitary or accompanied with plasma treatment - to increase the affinity between the colouring matter and the fibre was also recommended.