POLYAMIDE RESINS FOR HAIR 327 . .:.. ::: :. Figure 5. Effect of exposure at high humidity on length of curled tresses Top. Before humidity exposure Bottom. After humidity exposure on this mannequin was styled on one side with the new resin and on the other with one of the comparator lotions suggested by area salon man- agers who were consulted in the study. The mannequins were exposed to two conditions: (a) those of the high humidity room and (b) the motion and simulated wind obtained by placing the mannequin on the reciprocating, rapid-action, laboratory shaker shown in Fig. 7. In the next phase of the development, personal use in homes and in salons was planned to obtain observations under completely real- istic conditions. Thorough testing to assure safety was necessary even though there was no reason to think the resin might have toxic effects. Our Medical Department's studies included animal feeding tests and human skin contact patch tests for irritation and for possible sensitiza- tion. All gave favorable results. Analysis of shampooed hair samples treated with resin containing •4C tracer atoms showed that repeated use of lotion gave no significant retention of residual material after shampooing. •Vith safety thus assured, personal use studies were under- taken.

328 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Figure 6. Mannequin used to compare ease of styling and style retention Upper le[t. Styled hair Upper right. 1 hr 75% RH Lower le[t. 2 rain slow shaking Lower right. 2 min fast shaking Initially, two-side styling comparisons involving personal use were made by arranging for 42 shampoo and hair sets at a Wilmington salon. Volunteers agreed to have one side styled with the lotion they or their beauticians had been using and the other by use of the new lotion. Lotions were placed in opaque bottles labeled under a code so that when comparisons were made no one knew which lotion was used on either side. As directed, the beautician simply used bottle A on one side, and bottle 13 on the other. Hair spray was eliminated to maximize differences in the effects of lotions. Salon work was done in the morn- ing. Observations were made that afternoon and each of the next 2 days. The user's and two observers' comparisons of the two sides were made separately and recorded for study without anyone having knowl-