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Couroupita guianensis (Cannon ball tree) flowers and fruits are known to contain indigotin and indirubin. In this study an attempt is made to optimize the period for effective extraction of indigo from Couroupita guianensis fruit and application of the crude extract on the cotton fabric. Fermentation of the Couroupita guianensis fruit pulp for 5 days gave intense bluer pigment and hence was selected as the optimum period for fermentation. Major colouring components from Couroupita guianensis fruit extract were separated by thin layer chromatography using single solvent system, chloroform; which gives three pigments, violet, blue and pink with the Rf values of 0.88, 0.57, and 0.25 respectively. The Rf values, the wavelength of maximum absorption from UV-Visible spectroscopy, Fourier Transform Infrared (FTIR) spectrum and 1H Nuclear magnetic resonance (1H NMR) spectrum of blue pigment matched with that of synthetic indigo standard and that of the pink pigment matched with reported values of indirubin which is an isomer of indigotin. The % purity of indigo dye was found to be 26.46%. Dyeing of cotton fabric was carried out with the crude dye powder which gave comparable fastness properties vis-a-vis synthetic indigo.

Nowadays, all research efforts in the field of wet processing of textiles are directed towards shortening and simplification of the processing sequence. To minimise water and energy consumption, it has become necessary to combine several textile processing stages to reduce the number of operations or shorten the process time. An attempt was made to combine the pre-treatment and dyeing processes with optimal quantities of textile auxiliaries in single bath. In this process, individual stages of pre-treatment like desizing, scouring and bleaching followed by dyeing using direct dyes were carried out in a single bath without the usual intermediate washings. This process was carried out without replacing the liquor bath until the end of dyeing. An attempt was also made to dye a woven fabric at different stages, viz., grey, desizing and scouring. These efforts were made to conserve water and energy required for that particular pre-treatment process. The depth of dyeing and the colour fastness properties of all these dyed fabrics were then compared with a bleached fabric which was dyed with conventional method. The properties were at par with the conventional method. Moreover, the combined process saved 83.1 % water, 88.6 % energy (thermal) and 79.3 % time than the conventional processes. Thus, the process has been shown to be ecological, economical and energy conserving.

Purpose In nature, thousands of different colours and shades exist. Basic set of dyes, namely, yellow, red, blue and green are necessary for a complete colour gamut. Creating a complete gamut with natural dyes with one common extraction and application procedure is not exploited hitherto. The paper aims to discuss this issue. Design/methodology/approach In this study, an attempt was made to create a complete colour gamut with easily available natural dyes with one common extraction and application procedure. Findings Silk fabrics were dyed using various natural dyes alone and in combination to yield various shades, namely, yellow, red, green, blue. Pre-mordanting of silk fabrics was carried out with mordants, namely, alum, ferrous sulphate, copper sulphate, stannous chloride, potassium dichromate followed by dyeing. The fastness properties and colour strength values of all the shades obtained were determined. Originality/value Creating a complete gamut with natural dyes with one common extraction and application procedure is not exploited hitherto.