246 JOURNAL OF COSMETIC SCIENCE hair from Caucasians, reported to be undamaged, and purchased from DeMeo Brothers of New York City. This hair actually measured 14 inches. In some experiments, small tresses of highly coiled steam-set hair (12-inch hair), purchased from DeMeo Brothers, was also used. All experiments were conducted at 41 ±2% RH and room temperature. MAKING WEIGHTED HAIR FIBER LOOPS Hair fiber circles/loops (about 6.4 cm in diameter) were made from the 14-inch hair using tape (Scotch® brand mending tape) to bind long sections of the ends together (folding the hair back on itself over separate pieces of tape (using 4 x 4-cm-long sections of tape) to hold the fiber securely). A weight (10-50-gm load) was attached to the tape holding the fiber ends together, through a 15-cm-long wire (single-strand plastic #16 coated copper wire) forming a wire circle at one end to bind the fiber to the tape and a hook at the other end to attach the weight. IMP ACTING HAIR LOOP OVER STRAIGHT HAIR SECTION A straight horizontal hair was threaded through one of the fiber loops (described above) and the loop was weighted with a 20-gram load (total wt 21 g). The horizontal hair was held firmly and taped and clamped to the jaws of one vise and draped over the bottom jaw of a second vise (vise jaws 4.5 cm apart) and pulled taut with a 10-gram weight attached to the free end of the fiber. Then the part of the fiber on the vise jaw was taped to the bottom hard rubber jaw of the second vise to minimize slippage. The weighted loop was then dropped at a 15-cm height onto the horizontal hair fiber. IMPACTING HAIR LOOP OVER COMB TOOTH Hair fiber loops (6.4 cm in diameter) were made as described above. Each loop was placed over a comb tooth and a 50-gram or a 30-gram weight was connected to the wire, providing a total weight of 51 to 31 grams. The weight was raised up to the comb in the vise and dropped near the back of the comb tooth (15 cm) (Figure 1). The comb teeth used were of two types cut from a Blue Goody comb, with the measurements described below. The comb tooth measurements were made with a spindle-type caliper microm­ eter from General Tools Mfg. Inc.: Thick tooth: Tooth thickness 0.070 inches, tapering to 0.056 inches (tooth to about midpoint of micrometer spindle or approximately 1778 to 1422 microns) Fine tooth: Tooth thickness 0.049 inches, tapering to 0.03 7 inches (tooth to midpoint of micrometer spindle or approximately 1245 microns to 940 microns) ATTACHED-LOOP EXPERIMENTS A 14-inch hair fiber with tape on each end was hung over two adjacent thick teeth of a comb, held in a vise. Twenty-gram weights were attached to each end of that hair via clamps. One end of another 14-inch hair fiber was held firmly by taping it to a marked position on the table top alongside the vise, and the free end was fed between the two comb teeth and over the taut hair (Figure 2). A weight (10 to 30 grams) was attached

Weight ... . ··•........ IMPACT LOADING AND HAIR BREAKAGE Hair Loop 247 Figure 1. Schematic illustrating a hair loop impacting over a straight hair versus a hair over a comb tooth. 20gon each e d Figure 2. Schematic for attached-loop breakage. to the free end of this fiber, and it was raised either 8 or 15 cm and dropped so that the top hair impacted on the taut hair and the number of impacts required to break either of the hairs was noted. The broken hairs were saved for microscopic examination of the broken ends.