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To gain a more fundamental understanding of the frictional properties of skin, various parameters (hydration, oils, surfactants, etc) affecting skin friction were evaluated using a rotational friction technique. The rotational device utilized a motor-driven wheel. The wheel and drive shaft were connected to the motor through a flexible rubber coupling in such a way that friction encountered by the wheel caused a lateral displacement of the drive shaft which was monitored by a photocell and recorded on a strip-chart recorder.

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Scalp penetration of 7 hair dyes (oxidative and direct) that occurs under conditions of hair dye usage was evaluated for both rhesus monkey and man using 14C labeled materials by quantifying their absorbtion via urine assays. Both species showed a remarkably similar pattern of dye penetration. The extent of scalp penetration is slightly higher for direct dyes but in neither case does it exceed 1% of the applied dose.

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The equilibrium cleavage reactions of keratin disulfide with sulfite and mercaptans were studied. Experimental cleavage levels approximate closely those calculated on the basis of a derived equilibrium expression for the reaction employing the ionization con stants of the reactants and reaction products. A generalization of the equilibrium analysis leads to the conclusion that, in any nucleophilic attack on the disulfide bonds, the effect of pH on the equilibrium will depend primarily on the relative pK values of the thiol group of keratin and the attacking nucleophile. The pK of keratin thiol groups was determined by a novel swelling technique.