[Physiology of the horny layer: aspects for prevention and rehabilitation of occupational dermatitis (author's transl)].

The manifestation of professional eczematous dermatitis is conditioned by prolonged damage and subtoxic alteration of the epidermal horny layer (so-called "2 phases eczema"). The stratum corneum has three different functions of a barrier: protection against water-loss, alkali, and physical forces. The following rules apply: 1. Substances permeate the epidermis the more the higher their concentration and the less the thicker the stratum corneum (Fick's law). 2. Continuously applied alkaline solution is sustained by the stratum corneum without remarkable structural damage up to pH 10. 3. The stratum corneum becomes dry and brittle if its water content diminishes below 10%.