ALKYLOLAMIDES IN SHAMPOOS 31 reproducible results could be obtained. Foam volumes were rated visually on an arbitrary scale in which the volume generated by a 3% amine lauryl sulfate solution in soft water on unoiled hair was taken as 100. Where it was desired to run tests on oily hair, the buns were first oiled by placing them in narrow tubes and piperring onto each one 2 ml. of a pentane solution containing 2.25 gm. mineral oil and 2.25 gm. lanolin per 100 mi. the pentane was then evaporated ofF, leaving the hair treated with 3% by weight of mixed oils. This oily hair was then used in the shampoo tests. The detergents chosen for these lathering experiments were an amine lauryl sulfate and a triethanolamine dodecylbenzene sulfonate. These were run at a concentration of 3% active in both soft and hard water, and on both "dry" and oily hair. In addition, these anionics were blended with a water soluble lauric diethanolamide (Ninol AA62, also called Ninol 979) and tested in the same manner, to determine the effect of the alkylol- amide on the foam of the lauryl sulfate or the alkylaryl sulfonate. The results are presented in Table 3. TABLE 3--SHAMPOO TEST: EFFECT OF DIETHANOLAMIDE ON LATHER VOLUME OF ANIONICS Solution Applied Relative Lather Volume Anionic, % NINOL AA62, Type Water in Solution Unoiled Hair Oiled Hair dmine Lauryl Su/fate 3.0 Distilled 100 4(I 2.0 l'.b' Distilled 100 40 1.5 1.5 Distilled 100 50 0.75 2.25 Distilled 100 60 3.0 Distilled 100 40 3'. b' Hard (350 p.p.m.) 70 10 2.0 1'.•)' Hard (350 p.p.m.) 80 10 1.5 1.5 Hard (350 p.p.m.) 90 30 dmine dlkaryl Sulfonate 3.0 Distilled 100 40 2.0 l'.b' Distilled 100 90 1.5 1.5 Distilled 100 100 3.0 Hard (350 p.p.m.) 80 30 2.0 l'.b' Hard (350 p.p.m.) 90 90 1.5 1.5 Hard (350 p.p.m.) 100 100 One can see, the lather volume of the lauryl sulfate alone is high in soft water hard water reduces it slightly, and oiliness causes a marked reduc- tion. In the presence of both oil and hard water the lauryl sulfate foam almost disappears under the conditions of this test. (For this reason it would seem desirable to add sequestrants to lauryl sulfate shampoos in order to soften the water on the hair.) As increasing proportions of alkylol- amide are added to the lauryl sulfate there is no change in foam volume in soft water, but in hard water or with oil present, a moderate improvement occurs.

32 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Coming now to the alkylaryl sulfonate, the lather volume in soft and hard water on both "dry" and oily hair is about the same as for lauryl sulfate. On adding the alkylolamide, however, the lathering of the alkyl- aryl sulfonate in the presence of oil is increased remarkably. In fact the blend of alkylaryl and alkylolamide lathers as much in hard water on oily hair as the lauryl sulfate does in distilled water on unoiled hair. Based on this test, blends of alkylaryl sulfonates and lauric diethanol- amide give more foam than lauryl sulfates. Such blends are now commer- cially available. So far, only the volume of lather has been discussed. In all of these tests it was also noted that the "flash" or speed of lather formation was also greatly increased by addition of the amide. After the first few "kneadings" of the test pieces, it was practically always observed that the ones contain- ing amides were generating foam much faster than controls run with lauryl sulfate or alkylaryl sulfonate alone. In other words, the amides increase the flash foam of both types, thus making it possible to obtain good lather- ing on the first application to soiled hair. Another property of lathers considered important is the matter of texture, lauryl sulfates usually showing a smaller-bubbled, creamier foam than alkyl- aryls. Although this difference was difficult to observe in this test, there was some indication that the alkylolamide decreased the bubble size of the alkylaryl sulfonate. One of the main objections to the use of alkylaryl sulfonates in shampoos has been the sticky, or tacky, feeling they impart to hair and skin, especially in hard waters. As a by-product of the above test work, it was noted that the addition of alkylolamides completely overcame this difficulty. For instance, hand-washing tests carried out in hard water with alkylaryl sulfonate. alkylolamide blends, demonstrated that the pronounced tack- iness of the alkylaryls alone on the skin was completely eliminated. This has also been reported to occur on the hair. In other words, the alkylol- amides appear to exert some type of conditioning action, perhaps by being adsorbed onto protein surfaces. They also seem to impart a more slippery or soapy "feel" to the alkylaryl sulfonates, which is considered desirable. Some lathering tests were also carried out with coconut soaps, since these are still widely used in spite of the great popularity of synthetic detergent shampoos. Using the technique described above it was found that at a concentration of 3%, the soaps seems to produce somewhat more lather than the synthetics in either soft or hard water, or even with oil present. Addition of alkylolamides did not seem to increase this lather appreciably. The addition of alkylolamides to soap shampoos is, however, very useful in improving rinsibility by preventing deposition of insoluble limesoap curds onto the hair. Since a lauric diethanolamide like Ninol