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j. Soc. Cosmet. Chem., 29, 783-792 (December 1978) Prediction of hair assembly characteristics from single fiber properties C. R. ROBBINS and G. V. SCOTT Colgate-Palmolive Research Center, 909 River Road, Piscataway, NJ 08854. Received March 17, 1978. Synopsis An hypothesis is developed with relationships that PREDICT how changes in the behavior of HAIR ASSEMBLIES (tresses or heads) depend on changes in SINGLE FIBER PROPERTIES that are measurable, i.e., how changes in combing ease, flyaway, body, managability and style retention of hair assemblies relate to changes in fiber friction, stiffness, static charge, curvature, weight and diameter. From these relationships desired changes in assembly characteristics may be approached through changes in the fiber properties. INTRODUCTION A recent stimulating publication by Hough, Huey and Tolgyesi (1) reminded us of an internal report that we had written several years ago defining an approach for predicting characteristics of hair assemblies (tresses or hair on heads), using single fiber properties. Although the paper by Hough et al. is concerned only with hair body, our general approaches, essential definitions and conclusions are consistent. When these authors suggested "further discussions by individuals from different areas of the fiber and cosmetic fields," we decided to respond by putting our report into a publishable format. Types of testing used to evaluate the hair effects of cosmetic products are: measurement of physical properties of single fibers evaluation of fiber assemblies on tresses or on heads and perceptions of how products perform in blind, identified and sales testing. This manuscript is concerned only with the first two types of assessments, i.e., with relating measurable changes in single-fiber properties to the evaluation of changes in characteris- tics of fiber assemblies, where psychological perceptions from advertising, labelling and product properties such as fragrance, lather feel, viscosities, etc., are eliminated. DISCUSSION The consumer's vocabulary for describing the behavior of hair includes a number of assessment terms, such as combing ease, style retention, flyaway, body, raspiness, 783