*Editor’s note: Sometimes, a second look is all it takes to reinvent an old favorite or uncover hidden answers. Cosmetics & Toiletries has therefore dusted off its bound volumes to give readers another look at this December 2001 article on flexabrasion for measuring hair strength.
Tensile test methods have been successfully used to demonstrate improvements in the mechanical properties of hair, however they assess only one aspect of the physical processes of hair fracture that the consumer normally uses to evaluate the strength of hairs on the head. A more realistic test would involve all the elements—fiber bending (flexure), abrasion and extension—encountered in normal hair fracture. This paper provides background about a test method that does measure an amalgamation of these three elements, and gives examples of its use to evaluate a new ingredient for hair products that increases the strength of bleached hair.
The need for claims substantiation: In addition to the paramount need to ensure product safety, the cosmetics and toiletries industry is under increasing pressure from various authorities to justify advertised claims, particularly new ones. This is to ensure the protection of manufacturers from competitors who might otherwise gain an unfair advantage in the marketplace by false or unsubstantiated claims of benefit. There are two main routes to meeting this need for product claim substantiation, presented individually or, on occasion, presented in mutual support. The more difficult and expensive route analyzes panelists’ reactions to the use of the product. Recognized and reliable methods of experimental design and of statistical analysis are employed to seek out the significance of the particular benefit.
The other main route for claim substantiation is by laboratory instrumental evaluation. This route is the focus of the present paper. The advantage of this route for the product developer, particularly where isolated strands of hair are tested, can be in the ability to rapidly screen experimental materials and finished products for their effectiveness.