24 JOURNAL OF COSMETIC SCIENCE 40 ß Data of calibration points 0 Data ofthiswork ß Data of ref. 13 Data of ref. 14 Linear regression 0 0 10 20 30 40 in vivo SPF Figure 9. Correlation of SPF values obtained from step film calculations with parameters g = 0.269 and f = 0.935 and corresponding/, v/vo SPF data linear regression with intercept on abscissa = 0.55, slope = 0.83, and correlation coefficient r = 0.8957. lation of 0.83 indicates that the model tends to slightly underestimate the i. vivo SPF data. APPENDIX I Formulation of Standard P4 % w/w Trade name INCI name Supplier (as supplied) Part A Amphisol K Potassium cetyl phosphate Givaudan 2.00 Antaron WP 660 Tricontanyl PVP ISP 1.00 Myritol 318 Caprylic/capric triglyceride Henkel 5.00 Finsolv TN C•2 •5 alkyl benzoate Finetex 5.00 Cetiol SN Cetearyl isononanoate Henkel 5.00 Cutina GMS Glyceryl stearate Henkel 3.00 Lanette 16 Cetyl alcohol Henkel 1.00 DC 200 (350 mPas) Dimethicone Dow Corning 0.20 Tinosorb OMC Octyl methoxycinnamate Ciba Specialty Chemicals 5.00

STEP FILM MODEL FOR SPFs 25 Part B Water Aqua 47.80 Glycerin Glycerin 3.00 Phenonip Phenoxyethanol, Nipa 1.00 methylparaben, butylparaben, ethylparaben, propylparaben Part C Salcare SC 80 Steareth-10 ally ether/ Ciba Specialty 0.50 acrylates copolymer Chemicals Part D Tinosorb M Methylene bis-benzitriazolyl Ciba Specialty 20.00 tetramethylbutylphenol, Chemicals aqua, propylene glycol, decyl glucoside, xanthan gum Part E NaOH (10% Sodium hydroxide 0.50 solution) Heat phase A and phase B separately to 80øC. Pour phase B into phase A under moderate stirring. Homogenize with an Ultra Turrax at 11000 rpm for approximately 1 min. After cooling down to 45øC, add phase C. Before adding to phase D, adjust the pH of Tinosorb M to 5.5 with 20% citric acid solution. Again homogenize for 1 min. At 40øC adjust the pH between 6.0 and 6.5 with phase E. APPENDIX II Description of the First Formulation Referred to in Table II. (Alterations in the contents of UV absorbers in the other formulations of Table II were compensated only by changing the amount of water, whereas the other ingredients were kept constant.) % w/w Trade name INCI name Supplier as supplied) Part A Part B Part C Part D Amphisol K Potassium cetyl phosphate Givaudan 2.00 Myritol 318 Caprylic/capric triglyceride Henkel 5.00 Finsolv TN C•2_15 alkyl benzoate Finerex 5.00 Cetiol SN Cetearyl isononanoate Henkel 5.00 Cutina GMS Glyceryl stearate Henkel 3.00 Lanette 16 Cetyl alcohol Henkel 1.00 Tinosorb OMC Octyl methoxycinnamate Ciba Specialty 5.00 Chemicals Water Aqua Propyleneglycol Propyleneglycol Phenonip Phenoxyethanol, methylparaben, butylparaben, ethylparaben, propylparaben Tinosorb M Methylene bis-benzitriazolyl tetramethylbutylphenol, aqua, propylene glycol, decyl glucoside, xanthan gum Salcare SC 80 NaOH (10% solution) Steareth-10 ally ether/ acrylates copolymer Sodium hydroxide Nipa Ciba Specialty Chemicals Ciba Specialty Chemicals 66.30 3.00 1.00 2.00 0.50 0.20