2010 TRI/PRINCETON CONFERENCE 97 SHAMPOO AND CONDITIONER MEASUREMENTS ON HAIR TRESSES Using vertically hung tresses of any shade, it is possible to measure the effi cacy of a treat- ment such as shampoo and conditioner on the alignment of the hair fi bers. Figure 19 below shows images in the NIR region of two vertically hung oriental hair tresses (blond and brown). Images on the left show the untreated hair tresses while the images on the right show the hair tresses after application of a shampoo + conditioner that claims to smooth the hair and facilitate the combing. The hair appears more aligned in the orientation images (Figure 19 (b)) as the proportion of fi bers with a small angle relatively to the vertical (black pixels) is increased. Figure 18. Histograms representing the angular distribution for each tress. Table I Table of Mean Values and Standard Deviations (W) of the Histograms Mean (deg) W (deg) Straight −4.8 13.2 Curly 1 −4.7 19.9 Curly 2 n/a ∞

JOURNAL OF COSMETIC SCIENCE 98 Table II Table Showing the Standard Deviation Variations of the Histograms for Untreated and Treated Hair Tresses W (deg.) tress 1 W (deg.) tress 2 Untreated 7.9 ± 0.2 6.5 ± 0.3 Shampoo + conditioner 5.3 ± 0.1 4.4 ± 0.1 Variation (%) −33 −32 Table II shows the calculation of the standard deviations for each tress. The results show a decrease of the standard deviation of about 33% on both tresses after application of the shampoo and conditioner. The hair is about three times more aligned after treatment. FULL HEAD In vivo. The system resolution and fi eld of view coupled with a small acquisition time (about 1s) allows in vivo measurements on human models. Figure 20 shows two examples of measurement for two different shades of hair. Figure 19. (a) NIR images of vertically untreated oriental hair tresses (left) and the same tresses with a shampoo + conditioner treatment (right) and their corresponding orientation images (b).