The greasiness of moisturizers: A methodological study

The aim of this study was to investigate if simple blotting can be used no provide reproducible quantitative data on the amount of excess moisturizer. Simple blotting of excess moisturizer was studied, changing the volume applied, the time allowed for absorption (before blotting), the time allowed for blotting, the area studied, the region studied, the blotting pressure, and the type of blotting paper. The coefficient of variation was calculated for each parameter. A standardized procedure is described: application of 50 μl/25 cm² of moisturizer on volar forearm skin. After 20 minutes blotting was performed with a 25 cm² (5 by 5 cm) piece of ordinary filter paper with pores of medium size. Blotting was done for 120 seconds with firm pressure applied by a rubber-gloved hand. The method had a coefficient of variation of 23% and was significantly correlated to skin surface lipids as measured by the Sebumeter (p < 0.0001). Different commonly used moisturizers, as well as a protective cream and a simple gel, were compared using the new method, and the results were found to be in accordance with the clinical impression of cream greasiness. It appears to be possible to quantify non-absorbed moisturizer on the skin surface with an accuracy similar to that of other biophysiological methods. This simple method offers an improved possibility to classify moisturizers according to cosmetic acceptability and to quantify absorption for a better assessment of relative moisturizer efficacy.