! JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS 852 The mandrel with attached tress was placed vertically in a test tube 18 X 150 mm and a commercial waving solution containing 7% w/v thioglycolic acid adjusted to pH 9.4 with ammonia was added, sufficient to cover mandrel plus about one inch. After six minutes, the mandrel and attached tress were rinsed five times, with warm (about 50 øC) water. A commercial neutralizing solution containing 9-11% w/v sodium bromate, with and without addition of 30-36% w/v magnesium sulfate (U.S.P.), was then added, and after eight minutes the mandrel and at- tached tress were rinsed three times in warm (about 50 øC) water fol- lowed three times by cold (about 25 øC) water. The mandrel with attached tress was dried by rolling in facial tissue and the tress was removed after about five minutes. PERFORMANCE TESTS Air Stability Air stability tests and measurements were done 5 to 10 minutes after removal from the mandrel in order to allow any relaxation or change in shape of the tress to occur first. Waves were rated by numbers 0, 1, 2, 3: Wave 0--No loop or curl. Wave/--One loop or curl. Wave 2--Two complete loops or curls. Wave 3--(Highest rating)--From 2.5 to just under three loops, and, in addition, of "tight quality"--meaning a diameter close to that of the rod. Distances between Loop Crests (D2L) This measurement is the linear distance in mm from the beginning of the actually waved hair to the completion of the second loop. Best rat- ing: 12 mm, the actual distance on the mandrel. Water Stability After the air stability measurements, the tress was laid horizontally on the surface of a container of water and gently pressed into the water so that it floated freely just below the water's surface. A wave test (WT) rating was then given: Rating 3--Completely water stable, i.e., unaffected by water. May also be tightened by water, as in some cases following unwinding and

PERMANENT WAVE NEUTRALIZER 8•3 rewinding of the tress. Hairs regular, i.e., together and not apart from one another. Final shape of tress is helical. Rating 2 +--Unwinding and rewinding in water as previous, but hairs are not sufficiently regular to rate 3. Rating 2--Slightly straightened by water, but retaining most of curl. Rating 1 or O--Nearly (or completely) straightened out. Distance between Loop Crests in Water (D•L W) This is a more quantitative value for the water test. The closer it is to the D2L value, the more water-stable. Vertical Length Wet (VLW) Tress was lifted from water by tweezers, grasped at the cemented end, lightly touched to facial tissue in order to remove excess water, and its length measured in mm. Most tresses stable in both air and water gave values in the 37-39 mm range. A straight tress measured 62-64 mm. Inside Diameter (ID) Immediately after the VLW measurement, the tress was laid down on a facial tissue in such a way that it formed a series of concentric circles lying on top of one another. The ID of this "coil" was then measured in min. The best diameter was 7 min. After-Water Stability (A W) After taking the ID measurement, the tress, held by the cemented end, was first dipped into water, to allow it to lengthen itself naturally, and then lightly rolled on the surface of facial tissue and allowed to air- dry its shape and regularity were noted. The tresses were rated as "excellent," "good," "fair," etc., depending on how close their dimensions were to the original helical contour and on their regularity (Fig. 2). Repeated Waving of Same Tress To determine if the benefit given by added magnesium sulfate was re- tained upon repeated waving, individual tresses were waved six times in succession with at least one day between treatments. Air and water stability values were measured after each treatment. Serigraphic Measurements Tresses of 12 hairs were glued at one end and then taped at both ends with small squares of tape to produce a length between the facing edges