HAIR CARE 43
Hair integrity protected during chemical processes
n Ronald V. Lerum PhD – Grant Industries, US Anna Croom PhD – Grant Industries, US
Juan Carlos Salgado – Inventhia, Cosmetic Innovation, Peru
Preservation of the integrity of hair fibres requires an understanding of the structural and chemical composition of hair and the chemistry involved to counteract the damaging effects of the bleaching and color treatment processes. The hair structure is composed of the cuticle, cortex, and medulla.1
The cuticle is the outer protective
layer of the hair fibre, which provide the sensory and shine characteristics of hair. The cuticles overlap giving the appearance similar to roof shingles, thereby protecting the hair from chemical, physical, and environmental treatments. The cortex is the major component of the hair and is responsible for the mechanical strength and is responsible for the pigment colour of hair. The innermost layer is the medulla, which may be present or absent throughout the hair fibre. The structural integrity of hair is due to hairs’ specific chemical composition. The hair is primarily composed of proteins, lipids, and water. Human hair is composed of 65-95% protein, which influence hair textures such as curly, wavy, kinky or straight. The main component of human hair is keratin proteins, which are complex natural compounds that contribute to its physicochemical properties. Human hair keratin is unique to other types of keratin because of its higher content of cysteine residues relative to skin keratin (7.6% and 2.9%, respectively).2
A compositional
increase of cysteine residues in hair leads to a higher amount of inter- and intra- molecular disulfide linkages, translating to a durable structure due to covalent bonds.3 Hair is also comprised of 1-9% lipids, which contribute to enhanced conditioning properties, such as flexibility, surface gloss and lubricity of hair.3
of the hair provide structural reinforcement and rigidity. Water is another major component that can be found up to 32% by weight of hair.4
of a network of hydrogen bonds with proteins, thereby influencing the tensile strength, swelling, flexibility and shape of
Table 1: Amount of material used for the bleaching process
Material
Bleaching Powder
Developer (40v/v)
Granrepair Powerbond
Water Ratio
Control Test
Granrepair Powerbond Test (GRPB)
10 parts 20 parts 0
2.7 parts 1:2:0.27
10 parts 20 parts
2.7 parts 0
1:2:0.27
Table 1: Amount of material used for the bleaching process.
Water supports the formation
hair, as well as, the formation of salt-bridges. During the bleaching process and colour
Lipids in the internal part
treatment, it is crucial to introduce a product designed for improving hair integrity. These damaging processes affect the physical, mechanical, and surface properties of hair that leads to hair becoming dry and straw-like, frizzy, difficult to style and easily broken.5
During chemical
treatments, much of the hydrophobic lipids are stripped from the surface of the hair, leading it to be easily tangled due to increased friction and increased surface roughness. The hair bleaching composition and method has been discussed thoroughly in the patent literature.6,7
Briefly, one or
more cycles of applying high concentrations of oxidising agents with strong alkaline agents are applied onto hair to permanently decolour the hair. The bleaching process is often highly alkaline, (pH 9-13) resulting in a dramatic degradation of the external and internal structural integrity of the hair over repeated cycles. Hair lacks regenerative properties therefore it is important introduce components during the bleaching process and colour treatment to preserve and maintain the hair’s structural integrity and chemistry that reinforces the hair structure. Granrepair Powerbond (GRPB) is a
microemulsion (INCI: Water (and) Butylene Glycol (and) Bis-PCA Dimethicone (and) Disodium PEG-12 Dimethicone Sulfosuccinate (and) Aminomethyl Propanol) that was designed with distinctive properties to restore hair fibre integrity during the bleaching and colour treatment process. Granrepair Powerbond was formulated to provide compatibility with the bleaching and colour systems to ensure the efficacy of these treatments without interference.
Figure 1: Virgin black hair tresses bleached for 3 cycles. Control tress (left) appears damaged. Granrepair Powerbond treated tress (right) appears healthy and conditioned.
September 2018
Figure 2: Virgin black hair tresses bleached for 4 cycles. Control tress (left) appears severely damaged. Granrepair Powerbond treated tress (right) appears significantly intact relative to the control.
Bis-PCA dimethicone is the active of
Granrepair Powerbond (now referred to as ‘the functionalised dimethicone’) that contains pyrrolidone carboxylic acid (PCA). The PCA functional group is found naturally
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