Anatomy of Hair Relaxer and Straightener Formulas

Nov 1, 2012 | Contact Author | By: Luigi Rigano, PhD, Studio Rigano Industrial Consulting Laboratories
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Title: Anatomy of Hair Relaxer and Straightener Formulas
hair relaxerx hair straightenerx curly hairx
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Many products currently on the hair care market relate to a woman’s attempt to partially or completely modify her curly, frizzy and tangled hair. Hair straightening and hair relaxing formulations have been invented to achieve the desire for straight hair.

There is a degree of overlap between these two categories of products. The term hair relaxer, according to Du Yung Hsiung, is used to describe products that provide a permanent straightening effect on heavily curled hair, while hair straighteners include all the other formulas with more temporary or lower levels of straightening efficacy.1 This distinction is reflected in their different chemical compositions and use conditions.

Chemistry of Curls

The structure of hair is comprised of α-keratin chains covalently bonded together by the disulfide bonds of cystines. When some ionized thiol groups (-S-) are present in this structure, the covalent link may be involved in a reversible reaction of sulfhydryl-sulfide interchange, resulting in curls.2

If the new sulfide bond is at a lower level of physical stress or without any stress, the reaction is favored toward its direction,resulting in the relaxation of the initial stress and in a new, extended keratin chain structure. This reaction, if sufficiently extended, causes hair straightening. Therefore, this interchange favors the breakdown of bonds under stress and the creation of new bonds in equilibrium with the extended system. The number of ionized sulfhydryl groups in the native α-keratin structure is limited at less than one thiol of the cysteine residue for every 10 disulfide bonds of cysteine.

Excerpt Only This is a shortened version or summary of the article you requested. To view the complete article, please log in or create an account. Registration is Free!

This content is adapted from an article in GCI Magazine. The original version can be found here.

 

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Biography: Luigi Rigano, PhD, Studio Rigano Industrial Consulting Laboratories

Luigi Rigano, PhD, is a consultant for the cosmetics industry, co-director of the Institute of Skin and Product Evaluation (ISPE), and head of Studio Rigano Industrial Consulting Laboratories, a laboratory he founded in 1986. He spent more than 15 years in R&D, production and technical positions at Unilever, Intercos, Givaudan and Schering-Plough Corp., and is an active member of the International Federation of Societies of Cosmetic Chemists (IFSCC) and of the register of chemists in the Lombardia region of Italy. Rigano serves as a consultant at the Milan Court and has authored more than 80 scientific articles on cosmetics, aesthetics and dermatology.

a-e

a Silsoft AX-E (INCI: Bis-Cetearyl Amodimethicone (and) Ceteareth-7 (and) Ceteareth-25) is a product manufactured by Momentive, Columbus, Ohio, USA.

b Crodasone Cystine (INCI: Cystine Bis-PG- Propyl Silanetriol (and) Water (aqua) is a product manufactured by Croda, Edison, N.J., USA.

c Zelo Velvet is a product manufactured by Boca Cosmetics Group., Boca Raton, Fla., USA.

d StraightWear Smoother is a product manufactured by the Macadamia Natural Oil Company, Chatsworth, Calif., USA.

e Plantasil Relaxcare (INCI: Potassium Silicates (and) Caprylyl/Capryl Glucoside (and) Glycerin) is a product manufactured by BASF, Ludwigshafen, Germany.

Formula 1. Lye relaxer

Formula 1. Lye relaxer

Formula 2. No-lye mix relaxer

Formula 2. No-lye mix relaxer

Formula 3. Keratin straightening treatment

Formula 3. Keratin straightening treatment

Formula 4. Professional hair straightener

Formula 4. Professional hair straightener

Formula 5. Humidity-resistant smoothing and straightening cream

Formula 5. Humidity-resistant smoothing and straightening cream

Formula 6. Hair relaxer kit

Formula 6. Hair relaxer kit

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