QUANTITATIVE CHARACTERIZATION OF COMBING FORCE 777 .: iii•:•" : :":':'• .•..d•:•Z '•::':. • : !i.•1•" .•i :. .... ':•.:.:• .•,•... :' •: -'• ..... ?--'"'•e •' :•:.' ' '• " • -'%' •:""• •'•:•i• •"!• • .:!:..: .... •( i:i• % •--..•'•' :• .: :•:•:: •: ' i::.•.: • • :'•-: : • : • :.::: ...•'• :: ..... .•-: 'E •-::.•::: .'•.•',:• .':, ':': ß : •.,.::-...."--•::•'•.•"•..'• ...•:'::..:..:.' "'"-',:.:.':::"• ::'...:...:•'•:•::'..':'..':.'."'"': ............................. ß ß ...................................................... Figure 4. Same view as Fig. 3 after the strands have been inserted in the comb "creme rinses," label instructions required further rinsing at this point. This was done when necessary. The combing force was again determined and the results reported as "per cent residual combing force," calculated as: combing force of treated tress x 100. combing force of tress prior to treatment For measurement of the "dry combing force," tresses weighing approximately 4.75 g were used, with each tress being dried with a warm air hair drier before each series of measurements. For both wet and dry hair, care was taken by the operator to distribute the strands of hair in an even and reproducible manner between the teeth of the comb. It was also found necessary to use each tress as its own control and to repeat each measurement from 15 to 25 times. Despite these precautions, the average values of the per cent residual combing force were found to have a standard deviation of up to 20%. This procedure was therefore unable to de- tect small changes in combing force upon cosmetic treatment.

778 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Table I Comparison of Wet and Dry Combing Force a Force (g) Tress No. I 2 "Tress weight -• 4.75 g. Dry 12 4- 3 13 4- 2 Wet 95 4- 20 88 4- 5 Table II Effect of Conditioners on Wet Combing Force Combing Force (g) Product A B C D Before treatment 59 4- 7 54 q- 5 51 + 7 51 4- 4 After treatment 28 4- 3 41 4- 5 37 4- 4 23 4- 3 Residual, % 64 76 73 45 I•ESULTS The results of wet and dry combing force measurements of each of two tresses are compared in Table I. In this experiment, the tress weights were approximately 4.75 g. Reproducibility of the measured wet and dry combing forces for each tress is typical for this procedure, as discussed above. It can be observed that the wet combing force is much higher than the dry combing force of the same tress. Possible reasons for this will be discussed below. Table II lists the reductions in wet combing force found after application of 0.2 ml of 4 commercial hair 'conditioners. The results are the average of at least 25 measurements on several tresses for each product. In accordance with label instructions, the tresses treated with A, B, and C were rinsed with dis- tilled water before measurement. In each case, the rinsing lowered the resid- ual combing force significantly. Product D, which gave the largest reduction of combing force, was used in further studies. A comparison of the reduction of wet and dry combing force resulting from use of Product D is found in Table III. The wet combing force of the hair af- ter conditioning was reduced to approximately one-half of its initial value, while the dry combing force showed little, if any, significant decrease. The effect of amount of conditioner applied is illustrated in Fig. 5. An equal volume, 0.2 ml, of each of several aqueous dilutions of conditioner D was ap- plied to each tress. The calculated value of the standard deviation is included with each experimental result. There was a de?rease in the degree of reduc- tion of combing force as the product is diluted however, even at high dilu- tions, the effect still appears to be significant.