POLYAMIDE RESINS FOR HAIR 331 not be made. Under these conditions, only large and important dif- ferences could be noted. Curiosity prompted a number of men to try the polyamide lotion. Those making style changes used the lotion consistently as the most satisfactory solution to the problem of retraining hair to a new style. SUMMARY Comparing results from the personal use and from laboratory eval- uations of these hair care resins validates the laboratory methods used. However, realism of the personal evaluation studies makes them more reliable. Both are needed. The more expensive, personal use studies are less adapted for initial phases of a study involving, as this one, the evaluation of a large number of compositions. The work has also demonstrated the compatibility of the aminopoly- amide polymer structure with hair and its versatility making it adapt- able to specific requirements of hair care uses. By using reactive and nonreactive derivatives of the amine, a permanent, shampoo-resistant hair conditioner and a readily removed lotion have been developed to give easily managed hair with improved quality and style retention. (Received October 14, 1971) REFEI•I•NCES (1) Sagatin, Edward, Ed., Cosmetics Science and Technology, Interscier•ce, New York, 1957, p. 618.

1. So•. Cosmet. Chern., 23• 333-345 (May 23, 1972) Analytical Procedures and Evaluation of Sunscreens BORIS M. CUMPELIK, B.S.* Presented October 11, 1971, Joint Symposium of the Association o[ cial Analytical Chemists-Society o[ Cosmetic Chemists, Washington, D.C. Synopsis--The purpose of this paper is to present a simple, step-by-step ANALYTICAL METHOD for SUNSCREEN EVALUATION. Although there have been many publications dealing with the theory and mechanics of ULTRAVIOLET absorbers, there was a definite need for a practical easy-to-follow yet reliable method for the analytical chemist. INTRODUCTION Modern sunscreens are "transparent" preparations aimed at pro- tection of the human skin against the potentially harmful segment of the ultraviolet solar radiation. The ultraviolet (uv) region is roughly divided into three parts: far uv (short wave), middle uv, and near uv (or long wave). Short wave is lethal, and fortunately for us that part of radiation is absorbed by the earth's upper atmospheric strata. The concern therefore is with the middle and the near sections of uv radiation. In loose terms, the middle range uv causes reddening of hu- man skin, while the longer ultraviolet waves cause the often desirable tanning of the skin. However, it should be remembered that some erythema (reddening) is essential to trigger the production of melanin, with subsequent tanning. A potentially dangerous aspect of exposure to excessive ultraviolet irradiation is the time lag between actual exposure and the moment the effects of that exposure are first felt. * Van Dyk & Co., Inc., Main and William Sts., Belleville, N.J. 07109. 333