This document outlines tests to identify dyes and determine colorfastness. To identify dyes, test specimens are treated with solvents which cause sulphur, oxidation black and vat dyes to decolorize or change shade. Vat dyes can be restored with developer. Sodium sulphoxylate formaldehyde-glycol solution with sodium hydroxide decolorizes or alters the shade. Colorfastness to rubbing is determined by rubbing a specimen against a white cloth and comparing color transfer. Colorfastness to washing is tested by laundering specimens in a LaunderOmeter and evaluating color change and staining on a multifiber fabric.

2. The Test Specimen is successively teated with a)50% dimethylformamide

3. b)conc dimethlformamide and c) a mixture of glacial acetic acid and rectified spirit (1:1,v/v) at boil for 3 to 4 minutes with intermediate washing and squeezingAll sulphur, oxidation black and vat dyes decolourizes or change shade radically. The color of the test specimen is restored on exposure to air or with vat dye developer.<br />Take a fresh test specimen; boil it with sodium sulphoxylate formaldehyde-glycol solution containing few drops of sodium hydroxide solution (44%). Test specimen is decolorized or altered in shade.The solution is yellow, bluish red, etc. original color restored by vat-dye developer<br />Take test specimen. Treat it with ethylenediamine & glucose. Colour is more or less removed at boiling point.<br />Result: Conformed vat dye<br />Colour fastness to rubbing<br />Objective: The test is designed to determine the degree of colour that may transfer from the surface of coloured textile to other surface.<br />A coloured specimen fastned to the base of a crocmeter is rubbed with a white crock test cloth under controlled conditions. Colour transferred is compared with chromatic transfer scale or gray scale.<br />Result: Rating 5<br />Colour fastness to washing<br />Objective: To test colour fastness to washing<br />The test specimens are laundered under appropriate conditions of tempture, bleaching & abrasive action. The colour change of the test specimen & the staining of the multifiber fabric are visually evaluated.<br />The instrument used is called LaunderOmeter. <br />The size of the test sample is 2” x 4”. A muliti fibre fabric is attached to the sample.<br />Result: Rating 5<br />