The determination of the elasticity of hair is based on quantification of the elastic modulus, as shown in Figure 1.
The treatment with 1% DayMoist CLR led to a 13.7% improvement of hair condition as compared to placebo (see Figure 2).
The treatment with 1% DayMoist CLR led to 41.1% more effective crosslink protection (as determined with TD).
The treatment with 1% DayMoist CLR led to a 26.0% more effective α-helix protection, as determined with ΔH.
After 3 hr of UV irradiation, hair treated with 1% DayMoist CLR was effectively protected, whereas a noticeable difference in color was detected on hair treated with placebo.
DayMoist CLR™ (INCI: Water (aqua) (and) Hydrolyzed Corn Starch (and) Beta Vulgaris (Beet) Root Extract) is a skin care ingredient of natural origin, certified by Ecocert and NaTrue. This compound has been found to moisturize the skin after 24 hr by elevating the concentrations of the natural moisturizing factor (NMF) in the stratum corneum. However, its ability to improve the condition, elasticity, and color and heat protection parameters of hair also has been observed, as the following four experiments show.
Moisturization in hair is known to improve its elasticity. Therefore, to test the compound's ability to improve hair elasticity, tresses (50 hairs) of bleached hair were soaked either in water only, as the placebo, or in aqueous solutions of the compound at 1% for 10 min at 40°C. Hair was left to equilibrate over night at 60% relative humidity.
With an automated tensile test, the effect of DayMoist CLR™ on the elasticity of hair was determined. Using the tensile testing devicea, hair was extended at a constant deformation rate while the internal force/stress was measured. Within the first few percentages of extension, hair showed a spring-like behavior; the less force required to extend the spring, the more elastic the hair. The determination of the elasticity of hair was based on quantification of the elastic modulus, as shown in Figure 1. The treatment with 1% DayMoist CLR™ led to a significant increase in hair elasticity.
Hair conditioning is desired by many hair care consumers and the quantification of hair condition can be performed by wet combing experiments, since the combability of hair is perceived by the consumer as directly correlating to hair condition.
On tresses of bleached European hair, baseline (U) wet combability measurements were taken. The tresses were then treated with either a placebo (water) or 1% DayMoist CLR™ for 10 min. The hair tresses were dried to 60% water content, and measurements were taken again (T). Experiments were performed in an air conditioned room, T = 21 ± 1°C, 50 ± 5% relative humidity, and measurements were taken with a tensile testing deviceb. The treatment with 1% DayMoist CLR™ led to a 13.7% improvement in hair condition, as compared with the placebo (see Figure 2).
As consumers increasingly use hair straighteners, curling irons and blow dryers, this heat exposure leads to significant hair damage, especially in the cortex. Consequently, hair shows an increased loss in strength, leading to increased breakage and formation of split ends.
With High Pressure Differential Scanning Calorimetry (HP DSC), the thermal behavior of hair can be recorded under controlled heating, and both peak temperature (TD) and denaturation enthalphy (ΔH) can be determined. In TD, the denaturation temperature of keratinous structures in the cortex of hair is measured for the cross-link density between the α-helical keratin structures. ΔH is the energy required for α-helix denaturation, a measure of the structural integrity of the α-helical keratin structures.
To assess heat the protection capacity of DayMoist CLR™, undamaged European hair tresses 21 cm in length were treated with either the compound or the water-only placebo for 10 min and were flat ironed (6 min, 200°C), after which the moisture content was adjusted to 60. This process was repeated for a total of 10 cycles. TD and ΔH were determined after the last heat cycle. Measurements were performed with a DSCc.
Treatment with 1% DayMoist CLR™ led to a 41.1% improvement in crosslink protection, as determined by TD, shown in Figure 3, and a 26.0% improvement in α-helix protection, as determined with ΔH and shown in Figure 4, compared with the placebo.
Dyed hair is subject to color fade as a consequence of light exposure. The ability of DayMoist CLR™ to protect against color fade was therefore determined by quantifying hair color with a CIELAB-technology, leading to lightness (L), green-red (a) and blue-yellow (b) values. Noticeable, visual color difference after a defined irradiation of hair with UV light was determined by calculating ΔE using the following formula:
ΔE = ((ΔL)2 + (Δa)2 + (Δb)2)½
where ΔE < 2 = no noticeable, visual color difference, and ΔE > 2 = noticeable, visual color difference.
The colorimetric values (L*a*b) of dyed (red) hair tresses were determined, after which the tresses were treated with the corn starch/beet extract compound or the water only placebo for 10 min. The tresses were dried for 18 hr (T = 21 ± 1°C, 50 ± 5% relative humidity) and at t = 0, the ΔE was determined. The tresses were then irradiated with UV light using a xenon light sourced (300-800 nm) set to 450 W/m2 and 55°C. After 3 hr of irradiation, ΔE was determined again. Measurements were performed using a chromametere.
DayMoist CLR™, while already established as an effective moisturizing active for skin, also effectively moisturizes hair, improving the most consumer-relevant parameters for hair. It conditions hair, makes it more elastic, and protects hair against heat and color fade. Further, its natural source broadens the possibilities available to cosmetic chemists for the development of effective natural hair care formulations.
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