The measurement of gloss is very important in the efficacy testing of skin care, hair care and decorative cosmetics (lipsticks, make-up, etc.). Skin and hair are supposed to show a natural, luminous gloss without appearing oily.
The measurement is based on reflection.
Parallel white light is created by LEDs in the probe head.
To be able to emit light at 60° in a relatively small and uniquely designed measurement head, light is sent out at Glossymeter principle e0° and reflected by mirrors to 60°.
Two separate measurement channels measure the direct reflected light (again guided by a mirror in the same angle into the reflection channel) and the diffuse reflected (scattered) light.
The scattered/diffuse reflected light is measured at 0° (completely vertically above the measured surface) under the assumption that light is scattered in the same way over all degrees (diffuse channel).
So the Skin-Glossymeter GL 200 expresses both, the portion of directly reflected light (gloss) and the diffuse scattered portion from the skin or hair surface.
Another important point in determining the quality of a formulation is wash resistance and UV-resistance testing.
Standardized swatches, as well as obtained strands of hair from probands, can be used for wash- and uv-resistance-measurements.
Standardized ultrasonic-shampooing, UV-light irradiation in combination with LAB-measurements and standardized photographic documentation of probands, results in indications regarding wash-resistance and uv-resistance of human hair when – for example – analyzing hair colorations or color-shampoos.