A permanent waving composition for human hair without any skin sensitizing effect comprises as reducing agent 1,3-propanediol monothioglycollate and 1,3-propanediol dithioglycollate alone or in admixture with other reducing agents, wherein the content of 1,3-propanediol dithioglycollate is not more than 10%, preferably less than 5% by wt., calculated to the monoester.
The object of the invention is a new isomer mixture of 3-hydroxybutyl monothioglycollate and 3-hydroxy-1-methyl propyl monothioglycollate in a weight proportion of about 1.5:1 to 4:1, preferably about 2:1 to about 3:1, comprising less than 5%, preferably less than 2% by wt., of 1,3-butanediol thioglycollate, and its use as the sole or main reducing agent in compositions for permanent waving of human hair. The compositions have reduced smell, good waving properties and an extremely low sensitizing potential on human skin.
