MILDNESS ASSESSMENT TECHNIQUES 189 Table II Key Features of the Flex and Forearm Wash Methods Used in This Study Flex wash method Forearm wash method Implement used Identi-Plug © or Cerafoam sponge Masslinn © towel Bar/implement lathering 10 Seconds--rub sponge on bar 6 Seconds--rub towel on bar Wash area Inner elbow crease Inner forearm Wash time 60 Seconds 10 Seconds Residence time None 90 Seconds Rinse time 10-15 Seconds 15 Seconds Wash visits/day (final day) 3 2 (1) A separate flex wash study was conducted to evaluate the effect of the implement on the subjects' skin and on the study outcome. A procedure identical to the normal flex wash method was used, except that a single product was applied with either a sponge or a Masslinn © towel. Treatment (implement) assignments were made randomly so that the implements were used for an approximately equal number of times on the left and right arms. An evaporimeter (model EP-1C, ServoMed, Uppsalla, Sweden) was used to record transepidermal water loss (TEWL) values for treated sites to provide an indication of stratum corneum barrier integrity. STATISTICAL ANALYSIS Visual attribute scores at each time point were subjected to ANOVA to account for subject, side (left vs right), and product differences. Least squares attribute means for each test product at each evaluation time point were compared using t-tests. RESULTS AND DISCUSSION Ideally, an exaggerated wash protocol should have the ability to quickly and accurately predict mildness trends while maintaining its relevance to conditions of actual consumer use. The exaggerated protocols examined here are of five days' duration, significantly shorter than either of the home-use studies. Both use an area of the forearm as the wash site, and both use an implement to apply product. The methods differ in the type of implement used: the flex wash method uses a sponge to apply product while the forearm wash method uses a Masslinn © towel. Results obtained from exaggerated studies performed using two bar soap products coded A and B are reported in Table III. Only erythema (redness) results are reported for the flex wash method, since this method is not useful for measuring dryness (7). Both exaggerated wash methods differentiate between the products however, the flex and forearm methods yield different mildness pictures. In the flex method, product A induces significantly less erythema than product B, indicating that the former is the milder of the two products. The opposite was found in the case of the forearm wash method the data for both erythema and dryness indicate that product B is significantly milder than product A.

190 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Table III Comparison of Visual (Mildness) Results Obtained When Two Personal Cleansing (Soap) Bars Were Tested in 5-Day Exaggerated-Use and 4-Week Home-Use Studies Home-use test Flex Forearm wash test test Forearms Legs Test product Erythema Erythema Dryness Erythema Dryness Erythema Dryness A 0.77 1.61 1.76 0.96 1.17 0.94 2.43 B 2.45 0.76 1.09 0.85 1.07 0.82 2.47 p-value 0.0001 0.0001 0.0001 0.24 0.37 0.1 ! 0.05 Values reported are mean endpoint attribute scores differences are considered significant if p • 0.05. While these findings are useful from developmental and marketing standpoints, they do not answer the question of how mild the products will be under conditions of actual consumer use. Insight into the question is provided by data generated in a home-use study (Table III). Because this is an ad lib study, the differences observed are not as great as those in the exaggerated studies, and in only one instance is a significant difference found between the products. However, there is a clear trend in the data indicating that product B is milder than product A. This ranking is consistent with the ranking predicted by the forearm wash method, opposite that predicted by the flex wash method. To determine whether the contradictory mildness picture yielded by the flex and forearm wash methods was due to product composition (bars A and B both contain a high percentage of soap), the exaggerated wash procedures were repeated using two synthetic detergent (syndet) bars, coded C and D. The results of these studies, along with results generated in a 12 week home-use study, are reported in Table IV. The home-use results show product C to be milder than product D. Both exaggerated methods show a similar mildness trend, although the flex test fails to find a significant mildness difference between the products. During the performance of the flex studies, subjects developed a noticeable abrasion at the wash sites. This abrasion is atypical of normal use, and was not observed in any of the subjects participating in the forearm wash studies. As noted earlier, one of the Table IV Comparison of Visual (Mildness) Results Obtained When Two Personal Cleansing (Syndet) Bars Were Tested in 5-Day Exaggerated-Use and 12-Week Home-Use Studies Home-use test Flex Forearm wash test test Forearms Legs Test product Erythema Erythema Dryness Erythema Dryness Erythema Dryness C 0.52 1.27 1.11 0.28 0.76 0.45 2.16 D 0.56 1.82 1.61 0.31 0.98 0.70 2.70 p-value -NS- 0.0001 0.0001 -NS- 0.031 0.016 0.003 Values reported are mean endpoint attribute scores differences are considered significant if p • 0.05. P-values •0.5 are indicated by -NS-.