Hair dyes synthetic

F. Corbett, Hair Dyes, in K. Venkataraman, The Chemistry of Synthetic Dyes, Bd. 4, Kap. VII, Academic Press, New York London 1971. 

Hair dyes are of two types permanent and semipermanent. Permanent dyeing is achieved with a synthetic dye, applied with hydrogen peroxide that first bleaches the natural pigment melanin. Semipermanent dyes are generally made with vegetable extracts, such as henna, that coat rather than penetrate the hair shaft. There are a number of questions about the safety of synthetic hair dyes, since some of the products they contain cause cancer. 

So what should we make of all this The upshot of all this analysis would appear to be that modern hair dyes present no risk of causing cancer either among those who apply them or those on whose hair they are applied. If you are still not convinced that synthetic chemical dyes are safe, and yet you want to change the colour of your hair or hide any grey then you must perforce turn to the dyes of old - see box - but even some of these should come with test patches and a warning. 

Uses Organic synthesis mfg. of intermediates, paints, dyes, synthetic perfumes in microscopy colorant in hair dyes Manuf./Distrib. Aceto Aldrich Celanese Fluka Jarchem Ind. Monomer-Polymer Dajac Labs San Yuan Sigma Spectrum Quality Prods. 

Uses Azo dye intermediate photographic developing agent intermediate in mfg. of antioxidants, accelerators for rubber, synthetic fibers colorant for hair dyes, fur laboratory reagent... 

Kravtchenko, S. Lagrange, A. Guerin, F. Hair dye composition containing an azo-pyridinio-pyridone direct dye and a synthetic different dye, and a method for coloring of keratinic flbers. Fr. Demande FR 2864781, 2005 Chem. Abstr. 2005, 143, 120051. 

Hair coloring preparations have been in use since the ancient Egyptians, and recorded recipes exist in many cultures. These followed the traditional apphcation of plant extracts or metallic dyes, both of which still are used. In the latter part of the nineteenth century, synthetic organic compounds were discovered which eventually led to modem hair coloring. 

Disperse and other synthetic dyes can only be taken up by the hair at elevated temperatures, and for this reason the skins must be chrome-tanned. The shrinking temperature of suede has to be at least 20° C higher then the dyeing temperature. No mordant is required, unlike with oxidation dyes, and killing need be far less intensive, too. In actual fact the operation is more hair cleaning than a killing process. The suede portion is not dyed and can be cleaned very easily with standard washing auxiliaries. 

Synthetic mordants are rarely applied. Reactive dyes for hair or suede and soluble sulfur dyes for suede are chosen only for special purposes. Finally organic... 

The base readily penetrates the hair and promotes bleaching. The addition of stabilizers such as sodium pyrophosphate or sodium oxalate [16,17] retards the decomposition of hydrogen peroxide in the alkaline preparation and thus enhances the bleaching action. The same holds for complexing agents (seques-trants) such as ethylenediaminetetraacetic acid, which hinder decomposition due to traces of heavy metals. Thickening additives include carboxymethyl celluloses, xanthine derivatives, and synthetic polymers. Certain dyes can also be added. 

Use Azo dye intermediate, photographic developing agent, photochemical measurements, intermediate in manufacture of antioxidants and accelerators for rubber, synthetic fibers, laboratory reagent, dyeing hair and fur. 

OTHER COMMENTS used in dye and dyestuff intermediates for hair, fur, leather, cotton, and synthetics used in accelerating vulcanization, as an antioxidant, and stabilizer used in the preparation of antioxidants for petroleum fuels also used in the preparation of grease thickeners, electrical insulators, and rust removers useful as a catalyst and as an analytical reagent use in preparation of epoxy resins, synthetic fibers, heat-resistant polymers, and coatings for leather, paper, and textiles. 

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