Extraction, characterization and application of natural dyes from selected plants in Uganda for dyeing of cotton fabrics

Cotton fabrics were dyed with natural dyes derived from the crude bark extracts of Albizia coriaria, Morinda lucida, Syzygium cordatum and Vitellaria paradoxa dye-yielding plants collected in 2004 from Mukono and Mbale districts of Uganda. Natural dyes are becoming very important in industry for their less toxic tendencies as compared to synthetic dyes. They are friendly to the environment and hence their increasing demand worldwide. Many new enterprises, of different sizes, have began to cultivate, extract and apply natural dyes. Dyeing was carried out using the simultaneous mordanting method with 10% (o.w.f) of four selected mordants. CIELab coordinates, Chroma (C) and Hue (H) values were found to be dependent on type of mordant and nature of the phenolic composition of the crude extracts. The colour fastness values, both to light and washing, were very good and of textile importance. The colour absorption values (K/S) were calculated using the Kubelka–Munk equation from reflectance values and the same varied from plant to plant due to differences in molecular structures and substantivity to the cotton fabrics. The mordanting process resulted into varied values of colour depth, chroma (C) and hues (H) with significant changes in lightness values (L), and mordant dependent. Colour fastness properties to light and washing were good, between 3 and 4, suitable for textile application. Key words: Extraction, characterization, natural dyes, selected plants, Uganda.