METHOD FOR DANDRUFF SCALING 185 30 20 10 1' ' I I I ' I I 2 3 4 5 6 ß: DANDRUFF I: NON-DANDRUFF successive shampooings Figure 5. Weight of scales collected by six successive shampooings. Scale removal is nearly complete after two shampoos. The results clearly emphasize the inflammatory component in dandruff where the largest scales have the greatest proportion of incompletely keratinized cells. WEIGHT OF SINGLE CELLS VS COMBINED SCALES Against intuition, it turns out that on a weight basis, both in dandruff and non-dan- druff, single cells account for a greater mass than the total of small and large scales, assuming an average specific mass of one corneocyte of about 5.10 -7 mg (volume 450 •3, density 1.3) (7) (Figure 9). This study has produced several new findings. Surprisingly, single corneocytes comprise the great bulk of the mass of horny material produced by the scalp. The total counts averaged 1 x 108 and 2 x 108 single cells for non-dandruff and dandruff subjects,

186 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS 3O 2O 10 ß : DANDRUFF ß = NON-DANDRUFF n=12 • n=5 I 2 3 DAYS POST SHAM PO0 Figure 6. Kinetics of scale production one, two, and three days after shampooing. respectively. Dandruff is defined by the quantity of visible scales, made up of aggre- gates of hundreds to thousands of horny cells. The separation of dandruff from non-dan- druff is arbitrary since all scalps produce at least a few scales. Individuals decide on a personal basis whether or not they have scaling to a degree requiring treatment. In contrast to these subjective vagaries, the gravimetric measurement of large and small scales by our method furnishes an objective measurement of the dandruff process. For practical treatments, the sum of small and large scales (in milligrams) two days after a thorough preparative shampoo is a reliable and reproducible measurement of the degree of scaling, or if one prefers, the severity of dandruff. Scale weights correlate nicely with clinical gradings, but of course, are more accurate and are less likely to vary from one laboratory to another. Our data indicate that it does not appear necessary, for future experiments, to measure single cells in studying dandruff. Though greater in weight