614 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS ii S'TD'A 6 .sro.e sro. c Figu•'e 3. l•hotographie rating scale: Standard A: 6 equals no white margins nor uplifted dry flakes Standard B: 4 equals a few white margins, but no uplifted dry flakes Standard C: 2 equals many white margins and a few uplifted dry flakes Standard D: 0 equals totally distinct white margins and many uplifted dry flakes In an initial investigation, 30 panelists were treated at i skin area with an emollient eream, while a site on the opposite side remained untreated. Photo- graphs were taken of both sites after 6 and 24 h, and evaluated by 3 judges. Their scores were averaged and analyzed by the t-test statistic (23). The treated sites were scored nearly 3 points higher at 6 h and i point higher at 24 h (Table I), indicating that the visual benefits provided by the emollient cream could be readily discerned from the photographs. More recently, we have been examining the effect of various camera color filters on the quality of black-and-white photographs. Dent, in 1941, published an elegant study (24) on skin photography as a fun. ction of the wavelength of light reflected from the skin. He determined that detailed texture, definition and lines discerned under violet-blue lighting (300-450 nm) result from the fact that very little of this light penetrates below the stratum granulosum.

ASSESSMENT OF SKIN MOISTURIZATION Table 1 Mean Photographic Scores 615 Skin Sites Hours After Start Treated Untreated Null Probability a O 5.06 2.43 .001 24 3.72 2.55 .001 aBased on the t-test statisticaJ comparison. Thus, light directed into the camera can only be reflected from within the corneum, the lucidium and to a lesser extent the granulosum layers. Light of the green through red wavelengths (480 to 800 rim), however, is able to pene- trate further into the dermis. Photographs obtained under this light show veins and blood vessels, but no surface detail or texture. Gibson (25) has re- ported on a direct viewing system of goggles equipped with a monochromatic vision filter (MV812)* which converts colors to shades of gray. A gray photo- graphic scale is then used for evaluating levels of erythema or changes in skin pigmentation. We have confirmed Dent's observations, in particular, for Caucasian skin after elution with acetone for 30 sec. Photography using Panatomic-X© black-and-white film* and a Kodak CC50C-cyan filter* (passing mainly 550 nm and 740 nm) gives pictures with significantly more surface detail than photography using the same film but with a yellow filter equiva- lent to Kodak 81C (passing mainly 450 rim) (Fig. 4). C. SEM SEM investigations of panelists' skin have been used to correlate the in- fluence of the chemical composition of various preparations with the moistur- izing efficacy of these formulations in vivo. Bernstein and Jones (26, 27) have developed a replication method which would neither damage the skin nor become destroyed by the electron beam. Initially, a negative impression of the skin is formed by polymerization of 10:1 mixture of Silastic© 382 Elastomer* and RTV-Thinner* with stannous octoate. From this impression, *Ilford Inc., Ciba-Geigy Co., Paramus, NJ 07652. *Eastman Kodak, Rochester, NY 02142. •Dow Corning Corp., Midland, MI 48640.