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

854 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS AW R AT INGS Eoe[LLENT G00B FAiR POOR Figure 2. Waved tresses illustrating the AW ratings used in the waving experiments of the tape of 90 mm. An excess of hair was left at the unglued end to facilitate handling of the tress. These were then extended for 20% of their original length using a Model IP-2 Serigraph.* During extension, the tress was kept wet by draping a folded piece of filter paper (close to 90 * Manufactured by Scott Testers, Inc., Providence, R.I.