776 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS STRAIN • • ! GAUGE I • I,•i , i,i T R E S S---- I',•l,',,•l•t FIXED COMB Figure 2. Schematic diagram of combing force apparatus Figure 3. Close-up view of tress prior to insertion of its strands between the comb teeth ured 5 times, the tress rerinsed, etc., until up to 25 measurements were made. The tress was treated with the test material and then combed extensively to ensure the even distribution of the latter throughout the tress. For certain

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.