586 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS * - * Shear Modulus x - x Cutting Force o - o Tensile Modulus 1.2 1.1 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 10 20 30 40 50 60 70 80 90 100 %R.H. Figure 5. Normalized toodull or cutting force vs. l•er cent R.H. of the hair with in, creased temperature. Their extrapolated value was 21/2 to 3 min for complete hydration at 120øF. The hydration studies reported below were performed as follows: (1) a fiber was cut !0 times at ambient humidity to determine an equilibrium dry

CUTTING OF BEARD HAIR o- o Before x - x After 587 12 11 10 ø x x x o x o x o o 0 1 2 3 4 5 10 Time (Minutes! Figure 6. Hydration time before and after washing with sodium ]aury] sulfate (0.5 per cent) at 23 ø C value * (2) a stream of water or of a test solution was directed at the fiber, and cutting forces were determined as rapidly as possible during the first 9. rain after this, cuts were made at 1 min intervals (3) after 10 mina series of 10 cuts were made as a measure of the equilibrium cutting force in the wet state. *Fig. 5 shows that the "dry" f-t-c is relatively insensitive to variations in the range of 10 to 60 per cent relative humidity.