pH AND SKIN 331 FF 0,20 0,1O] 0,0 5 O• - O, OE -0,10- Infrared spectroscopy Group A pH4,5 pH 5,9 - -- pH ?,0 ß . pH ?,5 ß significant o not s•gnff•cant 6 •0 6'0 9'0 1•0 1•0 lg0 timin FF 0,30 0,201 0,10 0,05' O- - 0,0 5 - -0,10- lnfrored spectroscopy Group B f pH 4,5 ---- pH 5,9 .... pH %0 .. - pH 7,5 ß s•gnlf•cant o not slgqificant 3'0 6'0 9'0 'i0 •0 'i0 t/rain Figure 1. Hydration and dehydration after treatment with detergent solutions of different pH values-- infrared spectroscopic measurements.

332 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Ski 15- 10- 5- O- -5- -101 Corneometry Group A • pH --- pH .... pH ?,0 ......... pH ?,5 significont not significont Skt • 15- 10- 5- . -5- Corneomety Group B ß •) 30 60 90 1•0 1•0 1•0 timin pH --- pH 5,9 .... pH 7,0 .......... pH ?,5 m significQnt o r,,ot significont Figure 2. Hydration and dehydration after treatment with detergent solutions of different pH values-- corneometric skin capacitance measurements. pH 7.5 solutions, significantly different effects were measured at 30 minutes, and for the pH 7.0 and pH 7.5 solutions at 90 m•nutes. COMPARISON OF GROUPS A AND B WITH REGARD TO THE DEHYDRATIVE EFFECT OF THE DETERGENT SOLUTION AT DIFFERENT pH VALUES Figures 1 and 2 demonstrate that the dehydrative effect was greater in group A (younger subjects) than in group B (older subjects). This difference was significant for the infrared spectroscopic determinations only for the pH 7.5 solution at 30 minutes after treatment. In the case of the corneometric skin capacitance measurements, the following significant differences were found: for the pH 4.5 solution at 30 minutes after treatment for the