STABILITY TESTS ON MAKE-UP ITEMS 303 Bactericidal Actions of Some Mercurial Compounds on Hemolytic Strepto- cocci," •.A.MA., 136, 3641 (1948). (5) Klarmann, E.G., and Wright, Eleanor S., "Are Quaternary Ammonium Com- pounds Sporicidal?," Am. 5 •. Pharm., 122, 330-336 (1950). (6) Blank, 1. H., "Degerming the Cutane- ousSurface, 1. Quaternary Ammonium Compounds," •. Investig. DermatoL, 15, 249-256 (1950). (7) Price, P. B., and Bonnett, Alberta," "The Antibacterial Effects of G-5, G-11, and A-151 With S•pecial Reference to Their Use in the Production of a Germi- cidal Soap," Surgery, 24, 542-554 (1948). (8) Kelner, Albert, "Revival by Light," Sci. dm., 184, 22-25 (May, 1951). (9) Flett, L. H., Haring, R. C., Guiteras, A. F., and Shapiro, Rebecca L., "The Revival of Organisms Presumably Killed by Phenol," •. Bacteriol., 50, 591-595 (1945). (10) Price, P. B., "Reevaluation of Ethyl Alcohol as a Germicide," alrch. Surg., 60, 492-502 (1950). STABILITY TESTS ON LIPSTICK, FACE POWDER, AND MAKE-UP ITEMS* By H. HEINRICH, PH.D. Kolmar Laboratories, _inc., Milwaukee, [d/is. STABILITY TESTS for the pur- pose of this talk will be defined as tests made in the laboratory to guarantee stability while the prod- uct is in the stores and in the hands of the ultimate consumer. In this sense we may speak of stability tests as tests which assure the sal- ability of a product over an extended period of time. Everybody fully realizes that the requirements of salability vary and that every day standards become more rigid what constituted salability some years ago, may not constitute salability now. Let's assume that we have de- veloped a new product in the lab- oratory. We have made enough consumer tests to be sure that it is a desirable product. So the next step is to get into production. * Presented at the May 18, 1951, Meeting, New York City. We realize, at once, that our experi- ence with this new product is, after all, limited and we do not know whether the product would stand up under the conditions encountered in the stores and homes. We know from past experience approximately what conditions are encountered dur- ing shipping, storing, displaying, and use. We know, for instance, that a shipment during the winter months may encounter temperature varia- tions of some 70øF in addition to con- tinued jolting and rough treatment during shipment. In storage, the cosmetic may be on a shelf for a year or longer because of the habit of some storekeepers of picking up the nearest package regardless of age. We, furthermore, know that a cos- metic may be displayed in showcases under hot lights and the tempera- tures may go as high as 120øF. The consumer may leave the cosmetic

304 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS package open for any length of time, or on top of a hot radiator, or spill water on it. All of these things may happen to any one and all cosmetics. Some cosmetics can withstand these conditions better than others depending on the sus- ceptibility of the product, different tests have to be designed. In the time allotted it will not be possible to discuss every test in detail. There .will be some tests omitted because they are not made regularly. Furthermore, most of the tests are simple ones but every one of them has been time tested and is run as a matter of routine. We do not claim originality for any of them.. At the outset, a few false ideas should be corrected, such as, that an oven test is necessarily an accel- erated stability test and that keep- ing products in the sample room for weeks and months represents neces- sarily a shelf test. Make-up items are numerous but a discussion of their stability tests can be simplified by considering their physical characteristics rather than their chemical compositions. We have make-up items in loose powder form, dry compressed cakes, all oil preparations, emulsions, and suspensions. Make-up products in emulsion form are, right now, very popular. Loose F^cE PowI)ER A loose face powder is a dry mixture of pigments, inerts, and perfume. The most common rea- son why loose face powder loses its salability is in the loss of perfume. The stability of the perfume in a particular face powder can be readily checked by using the method of minimum quantity to discover whether perfume and powder are not reacting with each other. For this test one uses not more than 1/10 of 1 per cent perfume a good per- fume and suitable powder should maintain a slight but agreeable per- fumed note for at least two days while kept in a vessel open to the air. The usual failure is the dis- appearance of all of the perfume or the appearance of a phenolic or medicated odor. There is a great deal of difference between different perfumes and ingredients in the powder. The stability of the pigment used is of great concern to every manu- facturer of face powder. Unfortu- nately, not all shades can be pro- duced with earth colors exclusively and we are forced to use some or- ganic lakes and toners. These should be used very sparingly because they are not light-stable for any length of time. A simple stability test to check the light stability is to place a small puff on the smoothened surface of loose face powder and then put the sample into bright sunlight for about thirty minutes. Any appreciable bleaching action of the unprotected area will indicate possible trouble. Ordinarily, the other white ma- terials have less influence on the stability of the face powder. One exception may be zinc stearate. Zinc stearate has a tendency to de-