Hair consists primarily of the protein keratin, a polymer with a high concentration of the amino acids glycine, glutamic acid and cysteine. During the formation of the keratin fibre, the sulfhydryl functions of the cysteine residues oxidise to create disulphide bonds that give hairs their structure (Acton, 2013).
The natural look of hair can be altered either temporarily or permanently depending on which chemical bonds are changed (Baki and Alexander, 2015).
A keratin hair treatment is a method of chemical hair relaxation in which hair is coated with a keratin/formaldehyde solution (Ioannides, 2015). It straightens the hair by eliminating curls and frizz. This treatment is semi-permanent and will fade with time, typically 2 – 2.5 months (Ioannides, 2015). Also, newly developing hair will not be affected therefore the hair treatment procedures will need to be repeated at suitable intervals to maintain the appearance.
The results of hair keratin treatments can be seen below:
How it works
Once the hair is coated with the keratin / formaldehyde mixture, the formaldehyde molecules diffuse into it and crosslink the new keratin (from the mixture) with the keratin in the hair (Ioannides, 2015). By blowing saturated hair dry and by compressing it with a hot flat iron, the stylist accelerates the cross-linking reaction, transforming curly hair into flat hair (Ioannides, 2015).
Applying heat to the hair breaks the disulphide bonds allowing formaldehyde to form new bonds between the keratin chains of the hair fibre. The role of the keratin in the treatment mixture is to bind in a semi-permanent manner to the hair’s natural keratin, helping to hold the new shape (Schwarcz, 2011). This is supported by a study by Barba et al (2010) which revealed that application of keratin peptides and proteins to pre-treated hair improved the fibres’ moisture content and their mechanical properties.
- Acton, Q.A. (2013), Scleroproteins – Advances In Research And Application, Scholarly Editions, Atlanta, Georgia, USA, pp680
- Baki, G. and Alexander, K.S. (2015), Introduction To Cosmetic Formulation And Technology, John Wiley and Sons, New Jersey, USA, pp 506
- Barba, C., Scott, S., Roddick-Lanzilotta, A., Kelly, R., Manich, A.M., Parra, J.L. and Coderch, L. (2010), Restoring Important Proteins With Wool Keratin Proteins And Peptides, Fibers and Polymers, October2010, volume 11, Issue 7, pp1055.
- Ioannides, D. and Tosti, A. (2015), Alopecias – Practical Evaluation And Management, Current Problems in Dermatology, Karger, 2015, vol 47, pp 141
- Schwarcz, J. (2011), Dr Joe’s Health Lab: 164 Fascinating Insights Into The Science Of Medicine, Nutrition And Well-Being, Doubleday, Canada, 2011, pp 79-80