Comparative assessment of two hair care products (shampoo, conditioner, hairspray, gel, mousse, etc.) is performed routinely in the half-head test, a test that has been tried and proven for decades at the institute. The hair care properties of two products are directly compared by experts. For example: What does the foam of a shampoo feel like? Which shampoo is easier to foam? Which conditioner treatment results in softer hair and easier combing? Which styling product has the greater hold? Which product gives more volume? These and other questions are covered during the tests. In the half-head test two formulas can be compared optimally on selected test subjects under temperature-controlled conditions on the basis of essential product properties.

Trained hairdressers use the products to be tested and then assess important technological hairdressing parameters. During treatment the hairdressers part the hair of the test subjects in the middle, apply two products, each to one-half of the hair, and assess the cosmetic acceptance as well as major product properties such as take out properties, foam porosity, foam consistency, foam stability, spraying rate, spray pattern, residue on comb and hair, spreadability and much more. Additionally, important properties which have a direct effect on the hair’s condition are compared on the basis of individual parameters such as hold / strengthness, stickiness, comb out, anti-static effect, shine, volume, etc.

The parameters in the half-head test vary for the different product groups – shampoo, conditioner, hairspray, hair gel, hair mousse and other products. The test subjects are recruited according to the product requirements: fine, medium-length hair for volume shampoos, curly hair for anti-frizz shampoos, damaged hair for conditioners or hair-repair shampoos.

Drooping hair caused by absorbed product components is known as the build-up effect. The more often a product is used, the stronger this negative effect becomes. Therefore in a build-up study two products are used repeatedly in the half-head test and then assessed after each application.