EMOLLIENCY AND CHEMICAL STRUCTURE 637 Table I Base Formula Oil phase 7.0% 4.0 3.0 Water phase 4.0 0.5 0.4 81.1 lOO.O% Oil phase = 14% Residue on skin = 18.9% Emollient = 37% of residue Emollient Glyceryl monostearate (pure) Stearic acid XXX Propylene glycol USP Triethanolamine Sodium lauryl sulfate Water on the skin (Table I). Thus, once the water had evaporated, the residual film left on the skin contained 37% of the emollient under study. Each lotion (or cream) was aged at least 48 hours before being evaluated, to allow any crystal structure which was going to develop to do so. Mem- bers of a series being compared were about the same age when evaluated. Approximately equal amounts of the creams or lotions were applied one by one to the inner arm. Each was evaluated individually as it went through the complete cycle (from wet Initial Feel to dry End Feel) be- fore applying another to the skin. Successive changes in skin feel were noted as they occurred. To facilitate this process a work sheet was used (as shown in Fig. 1, filled out for PEG 200 monooleate). This evaluation form uses language reminiscent of that used in per- fumery. In place of "top note" Initial Feel is described, which includes such factors as the slip and texture of the cream. Middle Feel describes the cream's behavior during rub-out, factors such as absorption time, or whether it has a watery "break." Finally, End Feel (equivalent to "base notes" in perfumery) occurs only after complete dry-out and is described by words such as "oily," "tacky," "waxy," "draggy," "smooth," and "rich." Samples were always tested "blind." Each evaluator was requested to make note of his various sensations from the initial "wet" feel to the final "dry" stage, and then to rank that particular series in respect to anything he considered significant--such as variation in Initial Slip., in final End Feel, in oiliness or tackiness, etc. After the evaluation and

638 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS !•vlOLL I ENT PEG 2_00 iV•(3NO OLL:"t--•7'oe o O--• EVALUATION IN ]•'ULSION BASE #I•-.•.• --8--/ RATE ALL QUALITIES ON 1-5 SCALE (remarks in parenthesis - 1/3/5 SLIP (slight/medium/much) TEX•RE of Cream (light/mediu•hea•) DESCRIBE IN lt'ORDS (thin•pasty, lardy, etc.)•½, "BK•&K" QUALI• (water/no change/oily) "ABSORPTION" TIME (short/medium/prolonged) G•NGE IN TEX•RE (beco nes lighter/no chavie•eavier) [ LUBRIC•T QUALITIES (tacky/drags/"rolls") •sc• I• •'o•os (w•xr, •=dr, et•.) •,•,•,• C) lEND FEEL• (Skin-Feel after complete Dry-Out) SHOO•INESS (poor/good/velvety ri•) FRICTION (tacky/skids/drag/sl .drag/slip) OILINESS (dry/waxy/oily) MOISTNESS (dry/neutral/dewy) DESCRIBE IN I•'ORDS (raspy, Figure 1. Typical work sheet ranking were complete, the identity of emollients being tested in that particular series was revealed to the evaluator. All emollients were tested in a base chosen with several specific pur- poses in mind: First, we wanted a typical cosmetic formula familiar to most cosmetic chemists. In an earlier test series, it was found that per- sons asked to evaluate emollients did so with considerably better discern-