What is the dye used for clothing typically made from?


Almost all dyes typically used for clothing, especially commercially-made clothing, are synthetic, not made from natural sources. They are made from chemicals that ultimately derive from either coal or petroleum.

Indigo, a very popular dye used for blue denim, can be derived from plants such as the indigo plant or woad—there are some fifty species of plants around the world that produce this popular dye—but in actual practice, these days, it is produced synthetically. There are several different processes by which synthetic indigo may be made; in the currently most used industrial method, by which the vast majority of indigo is now made, it is manufactured from indoxyl, which is produced by the fusion of sodium phenylglycinate in a mixture of caustic soda and sodamide. The sodium phenylglycinate used in this reaction can be made from aniline; aniline, in turn, is prepared commercially by the catalytic hydrogenation of nitrobenzene or by the action of ammonia on chlorobenzene. The nitrobenzene is synthesized from benzene, which is obtained from coal or petroleum. So, ultimately, indigo is made from coal or petroleum. Plants are not used because synthesizing dye from fossil fuels is less expensive.

Synthetic dyes in general are often called "aniline dyes", because they were, at first made from aniline, but most dyes are no longer made from aniline. They are, however, synthesized from other chemicals derived from coal or petroleum, so the ultimate source is the same. Most commercially dyed cotton clothing is dyed with sulfur dyes, direct dyes, or reactive dyes, while most wool and nylon clothing is dyed with acid dyes. Polyester and acetate are dyed with disperse dyes, and acrylic and modacrylic are usually dyed with basic dyes.

For many years, direct dye was manufactured from benzidine or o-dianisidine, two chemicals known to be significantly carcinogenic. Unfortunately, the dyes metabolize back to these chemicals in the body, so their use is dangerous. Benzidine-containing dyes have since been largely phased out in the US, but were widely available in the form of packets of all-purpose dye, sold in grocery stores and pharmacies, though the 1970s. Dyes based on o-dianisidine can still be found in some consumer products, such as a "Tie Dye Color Cords" kit made by Consolidated Thread Mills, intended for use by children. Dyes which are not based on benzidine or o-dianisidine are much safer and more suitable for use by hobbyists or children.

Sources and further reading:
• How Indigo Is Made
• Health Hazard Alert-- Benzidine-, o-Tolidine-, and o-Dianisidine- Based Dyes
• Dyes and Dyeing Glossary: A Glossary of Terms for Materials and Processes in Textile Dyeing for Artists
• Aniline (Encyclopaedia Britannica)
• Dyes (Encyclopaedia Britannica)
• The Chemistry and Application of Dyes, edited by David R. Waring and Geoffrey Hallas


(Please help support this web site. Thank you.)