HAIR GLOSS 311 INDICATRIX in arbitrary units 8OO 550. 50 o 5 0 ,m•q o.o •.o •o 900 Indicotrices dark brown strand of o hair- measured in growing direction measured against growing direction measured across growing direction R e c e p t o r a n g I e Figure 11. Indicatrix shape variation with changing hair orientation. the optical incident plane and is illuminated in the direction of the hair growth. Compared to a completely plane surface, which would have its reflection maximum in the specular direction at a receptor angle of e 2 = e• = 30 ø (see indicatrix a in Figure 2), in this arrangement the maximum is shifted by 60-7 ø to smaller angles. Case C in Figure 5 explains this shift by the inclined position of the undamaged cuticle cells of the hair. The solid line confirms this assumption. By turning the strand 180 ø and illumi- nating it against the direction of growth, an equally sized maximum shift to larger angles is obtained. Because the solid indicatrix contains no principal different informa- tion besides the shift, we restricted our measurements to the illumination in the growth direction. Illumination across the growth direction (dotted line) mainly generates scat- tered light without a significant maximum. It is less suitable for gloss evaluation. EVALUATION OF TREATMENTS WITH CONDITIONING GLOSS TONICS AND A CONDITIONING HAIR RINSE The indicatrices given in Figures 12 and 13 represent two hair strands damaged by a perm and a hair bleach and sprayed with different conditioning gloss tonics (type I and type II). The initial indicatrices were taken before spraying (solid curves). Ten minutes after spraying, when the solvent was evaporated, a remarkable increase of the luminance maxima can be recognized as an indication for a gloss improvement. Even 24 hours after spraying an improvement against the non-sprayed strands is visible, although less remarkable. In addition to the increasing maximum, in Figure 13 a decrease of the half-value angle can be seen. Treatment with a tonic type II improves both gloss parameters and is

312 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS L n c e L N c e POUPlON P$SPlON P$SP40N E-5 880 66O 440 220 ./ , / ,, / ",, // xx x ' -5.0 +2'5.0 +5'5.0 +85.0 Permanent waved and bleached hair Additional treatment: Gloss Tonic Type I after 24 hours R e c e p t o r o rs g I e Figure 12. Indicatrix change caused by treatment with "gloss tonic type I." PCUP18N PG1P18N PO1P48N E-5 72O 540 560 180 -5 0 +25 0 +5'5.0 +85.0 Permanent waved and bleached hair Additional treatment: Gloss Tonic Type II after 24 hours R e c e p t o r a n g I e Figure 13. Indicatrix change caused by treatment with "gloss tonic type II." therefore expected to be accepted to an even higher degree than the treatment with type I. The use of a "conditioning hair rinse" on a strand damaged by a perm and a hair bleach is shown in Figure 14. The solid line again corresponds to the original strand, the dotted