788 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS SPECIFIC FOAM %DRAINAGE VOL. ML/G 5 MIN. :::. WATER ' 23øc 1•.2X• 1•2• ' :': ß :.10 : t0 • 15 50 70 ' I•r• I ,,, w . .• :: i0 15 :: SOLULAN 16: 'SPECIFIC FOAM % DRAINAGE VOL. ML/G s MIN. I •10 15 'CONTROL • SOLU•N 16 '•IONIZ•D Figure 3. Effect of varying additive concen- Figure 4. Effect of varying foam generating tration on properties of foam generated in de- conditions on foam properties of shampoos ionized water at 23øC, moderately hard water containing no additive, 2% derivative Sol. 16, (150 ppm Ca + +), deionized water at 45øC, and and 2 % ethoxylated stearyl alcohol deionized water at 45øC plus synthetic sebum. Shampoos contain O, 1, 2, and 5% derivative Sol. 16 as additive In deionized water at 23øC, the addition of derivative No. 16 in- creases both the specific foam volume and per cent drainage. The foam is improved from slightly dry to an acceptable range of richness and wet- ness. Although all foams containing this soluble lanolin derivative meet the acceptance criteria, the optimum improvement occurs at the 2% additive level. The effect of additive concentration is seen more dramatically in the tests carried out in 150-ppm hard water. Both specific foam volume and per cent drainage are improved so that they fall in the acceptable range as 1 and 2% of derivative No. 16 are added, but fall below the acceptance limits when the concentration is increased to 5%. This demonstrates that although foam properties can be improved by the presence of ap- propriate amounts of an additive like derivative No. 16, "overloading" the system can adversely affect performance. In deionized water at 45 øC, there is a progressive decrease in specific foam volume as the concentration of derivative No. 16 is increased. Both the 1 and 2% formulations are perfectly acceptable. In the presence of synthetic sebum at 45 øC, the addition of 1 or 2% derivative No. 16 improves the foam volume and drainage rates, with the optimum improvement noted at a concentration of 2%.

LANOLIN DERIVATIVES IN SHAMPOOS 789 Effect of Varying the Test Conditions Figure 4 illustrates the influence of altering the test conditions on spedfie foam volume and per cent drainage. It also shows the com- parative performances of the control, 2% derivative No. 16, and 2% ethoxylated stearyl alcohol. The control shampoo responds dramatically to altering the test con- ditions. In deionized water at 23 øC, the per cent drainage is below the acceptance range. The foam generated under these conditions consists of fairly small bubbles and appears dry, lacking luster and richness. Spedfie foam volume is depressed and per cent drainage is increased in moderately hard water, indicating the formation of a slightly wetter, less copious foam. In deionized water at 45 øC, both spedfie foam volume and per cent drainage are increased and fall within the acceptance limits. This is a larger bubble, richer, wetter foam than the one produced at room temperature. The addition of synthetic sebum at 45 øC produces a sig- nificant depression in both spedfie foam volume and per cent drainage. This foam is characterized by smaller wet bubbles that lack richness. The shampoo containing 2•/• of derivative No. i6 produces acceptable foams at all test conditions. All foams are medium bubble size, glossy, rich, and wet. This system exhibits less response to the variations in test conditions than the control shampoo, indicating a possible "sta- bilizing" effect of derivative No. 16 on foam properties. Moderately hard water has little effect on spedfie foam volume or per cent drain- age. Increasing the temperature to 45 øC reduces the spedfie foam volume slightly and increases the per cent drainage. The addition of synthetic sebum at 45 øC produces a further reduction in spedfie foam volume and also lowers the per cent drainage, bringing it closer to the middle of the acceptable range. Like the shampoo containing 2% of derivative No. 16, the shampoo containing 2% of ethoxylated stearyl alcohol shows less response to changing test conditions than the control system. However, none of these foams meet the acceptance criteria and only the foam produced in moderately hard water is better than the control foam. This improve- ment of foam properties in hard water appears to be typical of the ethoxylated materials studied. The dramatic difference between the performance of the shampoo containing ethoxylated lanolin alcohols (derivative No. 16) and that containing ethoxylated stearyl alcohol il- lustrates the importance of the size and structure of the lipophilie portion of the molecule in determining orientation at the interface.