68 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Figure 3. Twist Retention hair swatch Constant light source is attenuated by the transducer and relayed to a linear-response photocell. Voltage readings were recorded on an Omniscribe © 5110-22 recorder. Humid air was introduced into the sample chamber by passing purified compressed air through water, using glass dispersion tubes (Ace Glass a #7202 porosity C) to insure adequate moisture saturation (Fig. 1). Air flow rate was accurately controlled within a working range of 15 to 200 ml/min. Relative humidity of the test environmental air was determined to be 90 to 93 per cent R.H. Temperature was controlled at 21 to 25øC. TWIST RETENTION TESTING Approximately 0.25 g of 25 cm long Remi Blue String, European, brown hair 4 was saturated with water and combed into a swatch free of twists. The swatch was then care- fully bound at both ends with copper ring lugs (size 4) placed 203 mm apart. The hair swatch was allowed to dry at room temperature for 1 hr after which an adhesive was ap- plied at the ring lug/hair junctions to permanently affix the hair to the ring lugs. The watch was conditioned for 16 hr at 50 per cent relative humidity before adjusting (by trimming) to a net hair weight of 0.20 to 0.21 g (Fig. 3). ß :,Houston Instruments, l Houston Square, Austin, Texas 78753. a..Ace Glass Inc., Vineland, New Jersey 08360. •,DeMeo Brothers, New York, New York.

EVALUATION OF HAIR FIXATIVES 69 Figure 4. Twisted, fixative-saturated hair swatches on a retention panel The swatch was conditioned at 50 per cent R.H. and 22øC for 16 hr in a Tenny Envi- ronmental Chamber, Model TH-105, and then secured to a vertical Lucite ©6 retention panel. Copper wire was placed through the hole in the upper ring lug and attached to an alligator clip on the retention panel. The swatch was then rotated until th• lower ring lug was parallel to the retention panel. A clamp (approximately 12.5 g) was at- tached to the lower ring lug, twisted clockwise 720 degrees, and secured in place to prevent untwisfing (Fig. 4). Sufficient fixative solution was applied from an eyedropper at the upper ring lug to saturate the swatch (approximately 2 ml). Excess resin solution was allowed to drip off the swatch. It was then allowed to dry and condition (16 hr at 50 per cent R.H., 22øC) on the retention panel. The torsional chamber was equilibrated at 90 to 93 per cent R.H. A fixative-saturated swatch was removed from the retention panel and mounted in the Torsional Braid Ap- paratus taking care not to disturb bonding. The swatch was then allowed to untwist freely and the rate of untwisfing recorded as a function of time for a total of 120 min. 5Tenny Engineering Inc., Union, New Jersey. 6Lucite is a registered trademark of E.I. DuPont de Nemours & Co., Inc., Wilmington, Delaware.