LATHERING POTENTIAL OF SURFACTANTS 233 The effect of the salt form (eg. Na +, NH4 +, TEA +) on lather, however, was unexpected. It is observed that the triethanolamine salt formed looser, more rapidly draining lathers than either the sodium or ammonium salt and was significantly affected by the addition of the synthetic sebum loading. Incorporating the various additives shows that lauramide DEA and cocoamido propyl betaine tend to suppress lathering, in general, while the sarcosinate boosted lathering especially in the presence of the oily soil loading. Similarly, the ethoxylated lauryl sulfate surfactants were tested. Figures 12 and 13 show the effects of the same three additives with sodium lauryl ether(1)sulfate and sodium 80 sec. / Sarcosinate with Oil Sarcøsinate Lauramide/ •ura•ide/ / / DEA with • .• 60 drain time, 20 0 0 Na Lauryl Ether (1) Sulfate ,1.0% active 1.0% active Test Surfactant 0 Figure 12. Lather drainage time for surfactant mixtures--sodium laureth (1) sulfate. lauryl ether(3)sulfate, respectively. The data indiate that the increase in etherification, while known to lessen eye irritation, severely affects the lathering properties of the molecule. The effect of these same additives on sodium C•4-•6 olefin sulfonate is shown in Figure 14. This surfactant produces slightly more fluid lathers than does sodium lauryl sulfate and benefits from the addition of sarcosinate to produce a finer-bubbled, creamier lather. LATHER OF FORMULATED SHAMPOOS This method is also useful for estimating the maximum lather thickness obtainable with various consumer shampoos and new experimental formulations. Finished formulations were tested using 10% solutions in deionized water.

234 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS 80 40 drain time, sec. Na Lauroyl Sarcosinate with Oil I Na Lauroyl - , Sarcosinate ••,,,__ Cocoam•,•1•'-'--•t-•BetainePropyl -- with O, Cocoam_ido Lauramide Lauramide Prøpyl •.••111 • DEA with Oil D.......•.... • • ............ • •ll-"-' ....... 0 Na Lauryl Ether (3) Surfate 1.0% active 1.0% active Test Surfactant 0 Figure 13. Lather drainage time for surfactant mixtures--sodium laureth (3) sulfate. 80 Na Lauroyl I Na Lauroyl Sarcosinate • Sarcosinate with Oil --..... ..... DEA•/ Lauramide • / #' -/ DEA with -* / / / o," '--•/ / / / / // / Cocoam,do / / / / ../ ..... ••...• • • CocoamOII • ,,•- with 60 drain time, 20 0 0 Na C14-16 Olefin Sulfonate 1.0% active 1.0% active Test Surfactant 0 Figure 14. Lather drainage time for surfactant mixtures--sodium Cl4_16 olefin sulfonate.