Monday, December 15, 2014

Sources of dyes:

01. Animal origin:
Cochineal - obtained from an insect. It is extractable in water to give scarlet, crimson and orange color. It is expensive source.
02. Plant origin:
(i) Log wood – Obtained from the heart of the campeachy tree to give black and navy blue shades.
(ii) Madder/Alizarin – From the root of madder; on fermentation red color is obtained.
(iii) Indigo – The leaves of indigo bearing plants yields a yellow juice that rapidly turns blue when exposed to air.
03. Mineral origin:
(i) Prussian blue, (ii) Chrome yellow, (iii) Ultramarine etc.
04. Synthetic origin:
All natural dyes are replaced by synthetic dyes. They are cheaper and more permanent. The first synthetic dye is ‘mauve’ discovered by Perkin from aniline to quinine. Such aromatic hydrocarbons are obtained from coal tar, petroleum, crude oil etc.

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