232 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS 80 Na Lauroyl 60 Sarcosinate with Oil '•,•. Na •"••uroy• • '''-'• Sarcosinate 40 .**•' Cocoamido drain e•'*4 ,'/-- Propyl Betaine /•' with Oil time, • m J sec. mJl Cocoamido ß • **•' - Propyl Betaine 20 Lauramide• •'•..au ra mide 0 0 Ammonium Lauryl Sulfate 1.0% active 1.0% active Test Surfactant 0 Figure 10. Lather drainage time for surfactant mixtures--ammonium laury! sulfate. 80 sec. Na Lauroyl J ,• Sarcosinate with Oil Sarcosinate / Lauramide •' DEA with Oil $• • .. ...... ' .... ,........... Propyl Betaine • •='""='"='""=='=""='"='""" wifil Oil 60 drain time, 20 0 0 TEA Lau• ,I Sulfate 1.0% active 1.0% active Test Surfactant 0 Figure 11. Lather drainage time for surfactant mixtures--triethanolamine lauryl sulfate.

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.