619. JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Figure 1. Micrograph o[ damaged hair fiber (250X) showing exposed cortex , ."'."'•' .. ...:: : .,,'.:%.. '..'•.'. •.'•.•,, ..: :'":. ,-i- •. •.:":::. '.:. ...•.. .......... .-.-c',,....' .?--:...•..•-•:•....::¾:•- •,•••'" '• . '-- • :-•,•' ..., .• ...... .: ':, .... .• .... •.. "". :: .... . .... ...,...•. ..... .... ,••...••..•......•..•,..,•,• .,.. ø' -.. .. ß .• '* ....,,. '-"• ......... •,•.,,.,..'•'•." 'r'.:.-'•.'.. • ' .... ' ?' '"" ':'.Z•"' '*' • ...... • .." "•'•'. '- --'-•'•-'••' -:•r-½ . .:.' a... ,. % " •. % .*,,. . ',-,,,, . . .½•. . .•,f%.•.•--:c•.. -'.'-.-.•-•-,, .::..:-..-.-. ... .- • , ,•."" • .... .,.. :.?,-.,?:•:..•.-•,-•......•,.............:-. •' • ,.'" • "'•. '-i.. "....'"'"'??S?'"--,.•?."•'•:/:" '"'../'-'- ..... Figure 2. Micrograph o[ hair fiber pulled apart (300X)

SCANNING ELECTRON MICROSCOPIC TECHNIQUES 613 Figure 3. Micrograph of hair fiber pulled into a kn3t (800X) (note severe cuticle uplift) XVolfram and Lindemann employed the SEM to reveal the morphological characteristics of hair (3). They pointed out that the cuticle, often neglected when considering the stress-strain properties of hair, may in reality have a substantial effect. The concept of cuticle-cortex ratio was proposed to explain the supercontraction properties of hair. It was found that the level of super- contraction decreases with increasing relative cuticle (decreasing fiber diame- ter). Swift investigated the architectural changes of hair surfaces resulting from simple toiletry treatments (4). Although this study gives some insights in how to choose those products with optimum characteristics (e.g., cleaning by shampooing), it still implies that many hairs must be evaluated. Ayer and Thompson (5) utilized the SEM to stndy the coatability of hair spray fihns on individual and small groups of hairs. They investigated the,. use of several surfactants to improve the coatability and improve the properties of hair spray formulations such as luster and flaking. The technique involved spraying a hair swatch, drying, and gluing it to a mount. The sample was then shadowed with a gold film, placed in the SEM, and viewed.