Straightening Hair Safely With Cystine and Without Formaldehyde

Croda's Cystine Hair Smoothing System is a process that straightens many types of hair, from fine to coarse and also delivers protecting, restructuring and conditioning components.
Croda's Cystine Hair Smoothing System is a process that straightens many types of hair, from fine to coarse and also delivers protecting, restructuring and conditioning components.

Hair Straightening Options

Smooth, straight hair has long been a desire for women (and some men), especially those who wish to alter their natural wave or curl. Currently, consumers can obtain straight hair through heat straightening with a flat iron or blow-dryer and chemical straightening with relaxers or straightening treatments.

While all these methods can result in straight hair, each one has drawbacks. Blow-drying and flat ironing will only last until the next shampoo, and chemical relaxing can be harsh to the scalp and leave hair dry and damaged.

With the emergence of keratin straightening systems, it seemed that consumer’s straightening needs had been met, as this system was thought to be gentler than typical hair relaxers and would last for several months. Unfortunately, some of these systems are formulated with formaldehyde as the straightening active. In September 2011, the Cosmetic Ingredient Review (CIR) found both formaldehyde and methylene glycol unsafe in their current conditions of use in hair straightening systems. To answer consumers’ desires for straight hair, and comply with these rulings, Croda has developed the Cystine Hair Smoothing System, which gently relaxes the hair’s natural curl without added formaldehyde.

Safe Straightening Through Cystine

The Cystine Hair Smoothing System is comprised of four components: Cystine Smoothing Shampoo, Cystine Smoothing Treatment, Protein Leave-In Conditioner and Keravis Hair Strengthening Protein Conditioner. It straightens hair through: a sulfite/urea active straightening complex, heat  and protecting and restructuring proteins. The sulfite and urea combination work on the disulfide bonds of the hair to gently relax the hair fiber, resulting in the initial straightening.

The system then uses high concentrations of cystine, a major component of human hair. This is incorporated as Croda’s ingredient Crodasone Cystine (INCI: Cystine Bis-PG- Propyl Silanetriol (and) Water (aqua)), a copolymer of amino acids and silanol. Under heat, the silanol cross-links with the hair fiber to provide a protective shield on the surface of the hair, while the amino acids enhance the longevity of the treatment by aiding in the restructuring of the disulfide bonds. The result is sleeker, smoother hair that requires less time and effort to dry and style.

Other notable proteins in the system include Keravis (INCI: Water (aqua) (and) Hydrolyzed Vegetable Protein PG-Propyl Silanetriol), a strengthening protein that provides stronger, healthier-looking hair as well as Cropeptide W (INCI: Hydrolyzed Wheat Protein (and) Hydrolyzed Wheat Starch (and) Water (aqua)) and Hydrotriticum 2000 (INCI: Hydrolyzed Wheat Protein (and) Water (aqua)), which optimize the moisturization properties of the hair.

The Cystine Hair Smoothing System performance was evaluated in salon studies, where its smoothing performance was demonstrated on a variety of hair types. However, in order to further evaluate its effect on the hair fiber microscopically, an instrumental study was conducted where an Atomic force microscope (AFM) was used to take a 3D image of the topography of the hair fiber. Untreated hair was taken as a baseline, and hair treated with the cystine system was compared to hair treated with more traditional relaxers based on sodium hydroxide and thioglycolate. This comparison is depicted in Figure 1. From the AFM images, it is visibly evident that the hair fiber treated with the Cystine Hair Smoothing System most closely resembles the untreated hair.

The Cystine Hair Smoothing System can provide sleek, smooth hair with minimal damage and no added formaldehyde.


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