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J. Soc. Cosmet. Chem. 23 471479 (1972) ¸ 1972 Society of Cosmetic Chemists of Great Britain The effect of saturated salt solutions on the elastic properties of stratum corneum A. C. PARK and C. B. BADDIEL* Synopsis--ELASTIC MODULUS values have been obtained for native and solvent extracted STRATUM CORNEUM in saturated SOLUTIONS of various SALTS. In nearly every case the modulus was lowered significantly relative to its value at the same equivalent water activity in the vapour phase. This effect was attributed to disruption of the protein matrix of the CELL junctions which are believed to be responsible for the mechanical integrity of the corneum. A simple structural model is proposed which accounts for the response of the corneum to various TREATMENTS. INTRODUCTION The protection of the body against environmental hazards is main- tained by a thin layer of dead cells called the stratum corneum. The function of this outermost layer of the skin is to act as a barrier between the environ- ment and the complex system of living tissues which it covers. In the in vivo situation the stratum corneum must be able to respond quickly and without damage to mechanical stresses and strains imposed on it by various perturbations. As a result, studies in this and other laboratories (1-6) have been based on the premises that (i) maintenance of the mechanical integrity of this layer is important if it is to continue to fulfil its proper protective role, and (ii) changes in its mechanical properties can be used as a probe of those factors which influence its function and structure. The principal constituent (60-70•o dry weight), of the stratum corneum is a soft form of the fibrous protein, keratin, which is contained within the * Unilever Research Laboratory, 455 London Road, Isleworth, Middlesex. 471