322 JOURNAL OF COSMETIC SCIENCE Effect of Thermal Environmental Changes on the Physical Characteristics of Human Hair* Hiromi Kono*, Kaoru Suganuma **, Toshimasa Furukawa*** Cosmetics/Environmental Research Laboratory, FCG Research Institute, Inc.* C.T.C Japan Ltd.*** [2Changes in the physical characteristics (surface friction and bending characteristics) and perceptual qualities of human hair during temperature and humidity change were evaluated using KES and a sensory evaluation method. The standard setting for the temperature and the humidity was 20D, 65% RH, while low and dry was 15D, 30% RH and high and humid was 30•, 80% RH. Ten strands of hair were taken from the head of Japanese woman in her 20s who had never had her hair chemically treated. The process of perming, brushing, bleaching and more brushing was repeated 4 times on 5 of the 10 healthy strands to create a damaged condition. EThe healthy and damaged strands were then treated with typical cationic cellulose and silicone oil. We obtained the following results. 1) There was a correlation between the physical characteristics and sensory evaluation. 2) Both the healthy and damaged hair became smooth due to the reduced friction factor at high temperature and humidity. 3) Both the healthy and damaged hair became soft due to the reduced bending rigidity at high temperature and humidity. 4) It is easy to compare and examine the subtle differences due to various treatmentsUwhen the physical characteristics and sensory evaluation are performed under the standard conditions or low temperature and humidity conditions. •Key words : environment, humidity, hair, silicones, cationic cellulose, bending, friction, KES, surface, MIU

j. Cosmet. sc/., 51, 323-341 (September/October 2000) Papers presented at the Annual Scientific Seminar of the Society of Cosmetic Chemists (Friday's ProDraml May 11-12, 2000 Hilton Toronto Toronto, Ontario