Abstract

Dyes from nine selected dye-yielding plants namely Albizia coriaria (bark), Vitellaria paradoxa (bark), Curcuma longa Linn (roots), Indigofera arrecta (leaves), Syzygium cordatum (bark), Morinda lucida (bark), Morinda lucida (roots), Rubia cordifolia (roots),Mangifera indica (bark) and Justicia betonica (leaves), collected from Jinja, Kampala, Luwero, Mbarara, Mbale, Mukono, Pallisa, Arua and Wakiso districts of Uganda were evaluated for colour absorption and fastness on cotton fabrics. Colours were evaluated based on the CIELab colour order system. The highest and lowest values of chroma (C) were 68.34 in respect of C. longa Linn and 10.66 for J. betonica respectively.  Spectral reflectance curves for the dyed fabrics were indicative of yellowish-green to red colour shades between 550 and 700 nm. J. betonica, however, reflected about 65% of violet-blue light between 410 to 495 nm. The colour co-ordinates in colour space diagram were found to lie in the yellow-red quadrant for R. cordifolia, M. lucida, S. cordatum, C. longa L, M. indica, V. paradoxa and A. coriaria; in the yellow-green quadrant for I. arrecta and M. lucida(roots) and in the red-blue quadrant for J. betonica.  A. coriaria, V. paradoxa, M. lucida andS. cordatum had fairly good fastness ratings of 3 to 4. Lightness values varied from 58.57 for A. coriaria to 77.63 for I. arrecta. Results of this study demonstrate that dyes obtained from selected dye-yielding plants in Uganda can be good sources of natural dyes for the textile industry.

Key words: Plants, colour characterization, fastness, colour, lightness, chroma, Uganda.