MadSci Network: Chemistry

Re: how were permanent waves for hair discovered

Date: Thu Apr 16 08:46:20 1998
Area of science: Chemistry
ID: 890171305.Ch

how were permanent waves for hair discovered

what is the history of the development of permanent wave hair products and the different types of perms available today. How do they differ from earlier perms.

The chemistry of permanent waves is pretty straightforward. Hair is largely made of keratin, a protein that contains a lot of the amino acid cystine. The structure of cystine is shown at left. The image is color-coded: Proteins are long chains of amino acids, with links occurring between the nitrogens (amine groups) and the carbons which bear the oxygen atoms (carboxylic acid groups). The lovely thing about cysteine is that it can form disulfide bonds between protein chains. A disulfide bond is a bond between two sulfur atoms, protein-S-S-protein, and disulfide bonds cross-link the protein strands in a hair, causing it to hold its shape. The cross-links look something like this:

A permanent wave treatment has three steps:

  1. Break the disulfide bonds with a reducing agent.
  2. Shape the hair into the desired configuration, usually with curlers; the size of the curler will determine the tightness of the resulting curl.
  3. Reform the disulfide bonds in new positions, using an oxidizing agent.

ammonium thioglycolate:  NH4 O2CCH2SHTypically a chemical base is used as the reducing agent; the Ogilvie® home permanent I checked uses ammonium hydroxide -- a solution of ammonia, NH3, in water -- and ammonium thioglycolate as the active ingredients in the "Waving Lotion." These compounds (the ammonia and the thiol) account for the stench we associate with permanents.

The oxidizing agent, in the "Neutralizer," is good old hydrogen peroxide (H2O2), probably at a concentration similar to that in the disinfectant you have in your medicine cabinet.

Lots of other ingredients are listed, but they are all surfactants (soaps and detergents are surfactants; their function is to allow organic molecules to dissolve in water).

I am sorry that I can't say much about the history of permanent waves. The only thing I know about the history is something I picked up from The Autobiography of Malcolm X: in the 1930s and 1940s, black people were using lye (sodium hydroxide) to straighten their hair. My wife also tells me that lye has traditionally been used (as the reducing agent, of course) in home permanents.

For further information, I suggest you look for back issues of Chemical & Engineering News in a local college library.

  Dan Berger
  Bluffton College

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