HAIR GLOSS 317 CONCLUSIONS ß The estimation of gloss on hair surfaces by goniophotometric measurements requires a restriction to few parameters that correspond with the visible hair properties. An increase in the reflected amount of light in the reflection maximum and a decrease in the half-value angle of the indicatrix result in an improvement of gloss. ß An often underestimated problem, the preparation of testing strands, has been solved. The development of an acceptable technique to fix hair strands in a repro- ducible manner allows comparisons of the same samples before and after treatments by goniophotometric measurements. ß Although the human eye is indeed able to perceive small differences in gloss, it has problems in realizing the order of magnitude. The objective goniophotometric method was of great significance in detecting these small differences in gloss in absolute values. ß In some samples one can see which way the cuticle surface is influenced by hair rinses and hair gels. Commercial products like care sprays and glazes are only suitable to improve gloss on damaged hair strands. An increase of gloss on undamaged brown hair results from products that are able to smooth the surface of the cuticle and where the light reflection occurs at the treatment area. ß Consisting of various detailed information, gloss is actually a perception of light reflection recognized by the naked eye. Through goniophotometric measurements we can receive a lot of this detailed information, such as surface behavior, cuticle reflec- tion, hair damage, mode of action by different product treatments, smoothing of the cuticle layer, light absorption, and also the coloring of the hair. In spite of the great number of very interesting results, further refinements of the measuring device will be helpful. The study of hair surfaces by goniophotometric measurements represents an efficient method to solve these problems. REFERENCES (1) V. W. G. Harrison, Definition and Measurement of Gloss (Hefer & Sons Ltd., Cambridge, 1945). (2) R. F. Stamm, M. L. Garcia, and J. J. Fuchs, The optical properties of human hair, Parts I and II, J. Soc. Cosmet. Chem., 28, 571-599, 601-699 (1977). (3) H. K. Bustard and R. W. Smith, Investigation into the scattering of light by human hair, Appl. Optics, 30, 3485-3491, (1991). (4) M. Tetsuo, O. Masaaki, and H. Tadashi, Cosmet. Toiletr., 107, 53-59 (1992). (5) International Commission on Illumination, International Lighting Vocabulary, CIE Publ. No. 17.4 (Bureau Central de la Commission Electrotechnique Internationale, Geneva, 1987), p. 125. (6) International Standard ISO 2813: Paints and varnishes--Measurement of specular gloss of non-metallic paint films at 20 ø, 60 ø and 85 ø. 2nd ed. (1978). (7) W. Wundt, Ober das Binocularsehen und subjektive Farben, Poggendorj5 Annalen der Physik, 114, 163-168 (1861). (8) W. Czepluch, Glanz beim binokularen Sehen, Fortschr.-Ber. VDI-Z Reihe 17, Nr. 24 (VDI-Verlag, Dusseldorf, 1984). (9) International Commission on Illumination, CIE research note: Evaluation of the attribute of appear- ance called gloss, CIEJournal, 5, 41-56 (1986). (10) International Commission on Illumination: Colorimetry (E-1.3.1), CIE Publ. No. 15, 1971 Supplement No. 2 (TC-1.3), 1978 (Bureau de la Commission Electrotechnique Internationale, Geneva). (11) T. N. Cornsweet, Visual Perception (Academic Press, New York and London, 1970), p. 345. (12) Francis X. D. O'Donnel, PsychometricScaling of Gloss, Thesis, Rensselaer Polytechnic Institute, 1984.