ABSTRACT
Positive and Negative Standards Tests have been carried out with the same products repeatedly over a period of several years, and these will serve to demonstrate the effect of climatic conditions on skin physiology. The positive standard is a well-accepted former brand product that is currently unavailable on the European market. However, we have been making it at a constant quality level for years using the known formulation. This product, referred to hereafter as “standard L” (Table 2.1), is tolerated very well by the skin and demonstrates a moisture-retaining and skin-smoothing effect that can be easily classi‘ed in terms of physiologic effectiveness. This makes it an ideal standard, because other products can be classi‘ed as better or worse with respect to their effectiveness. Another aspect of demonstrating the effectiveness of products on skin physiology relates to negative effects that, for instance, can be induced by aggressive surfactants. Here, too, we have been using the same standard product for years. This is sodium dodecyl sulfate (SDS), which is referred to as the “negative standard” from now on.
