African hair: exploring the protective effects of natural oils and silicones

Due to its curvature and ellipticity, African hair tends to suffer higher level of breakage than other hair types. Its structure becomes compromised due to constant exposure to a variety of stresses such as washing, combing and heat styling, which further increases its propensity for breakage. The objective of this study was to determine the protective effects of two natural oils and two silicone polymers on African hair. The tested materials were: Crambe Anyssinica (Anyssinian) seed oil (ASO), Orbignya Oleifera (Babacu) seed oil (BSO), Bis-Aminopopyl Dimethicone (BAD) and Silicone Quaternium-22 (SQ22).The above active ingredients were applied to hair tresses as pre-treatments to grooming cycles and solar radiation exposure, estimated to be the equivalent to one month of damage. The protective effects of the treatments were assessed using the following tests: tensile stress requited to extend a wet fibre by 10%, the changes in hair colour after exposure to a sun simulator, torsional modulus measurements and thermogravimetric analysis. Wet tensile stress testing showed a reduction in tensile stress required for 10% extension in the case of silicone-treated hair, whilst the natural oils did not show a significant effect. There was a visually perceptible change to hair colour (expressed as ΔΕ value) before and after grooming in all tresses, indicating that none of the treatments were able to completely protect hair from solar damage; however, ASO and SQ22-treated hair was less discoloured. The TGA analysis determined that grooming and SR reduced the water content of the hair and the oil treatments did not have a protective effect.The dry torsional tests showed that ASO softened the hair cuticle. Overall, the results infer that the Anyssinian seed oil in particular offers some benefits to African hair, including maintaining cortex strength, mitigating the solar radiation-induced degradation of melanin, and increasing cuticle softness.It is expected that over extended period of time, these effects would contribute to maintaining the fibre’s manageability and reduced breakage, which are critical for keeping African hair in good condition. The remaining three active materials were less effective.