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.

PERMANENT WAVE NEUTRALIZER 85b mm long) over the hair which was liberally moistened with water by use of a medicine dropper. To determine the influence of the various waving procedures on the tensile strength of the hair, the tress was extended on the serigraph on one day, treated the next day, and extended again on the following day. The data were recorded in terms of the load required to extend the tress both before and after treatment. The second reading divided by the first times 100 was considered as the 20% index. RESULTS Table I compares the results of performance tests on tresses neu- tralized with bromate alone and bromate plus MgS0•. 7H20. The addi- tion of MgS0•. 7H20 to the bromate neutralizer resulted in: a. Higher initial wave values indicating the tress conformed more closely to the wave pattern on the mandrel. b. High WT values indicating better wave stability in water. c. Lower VLW values indicating stronger wave formation. d. Superior AW values indicating better wave stability in air. The same results are seen after six repeated wavings of the same tress. The results in Table II show a 27% increase in the 20% index for tresses waved with the neutralizer containing 30% w/v magnesium sul- fate (U.S.P.) as compared to tresses waved with the standard bromate neutralizer. Influence of Salt Concentration and Salt Uptake It was noted early in this study that the improvement to air stability given by the added salt increased as the concentration of the salt in- creased, and that for the desired air stability a minimum concentration was required. This is illustrated in an experiment in which waving performance was judged when increasing amounts of magnesium sulfate were added to a sodium bromate-containing neutralizer. The results are summarized in Table III. Note that the desired excellent stability was not achieved until over 24% of the salt was present. It had also been observed that ignition of hair waved with a neu- tralizer containing the added salt yielded an ash termed "uptake," in which the cation of the salt could be chemically demonstrated. In order to relate salt content, performance, and uptake, the same neu- tralizers listed in Table III were used to wave a series of tresses which