HAIR COLORING--MODERN FORMULATION CONSIDERATIONS 305 color yield. Silicone and other antifoams are excellent dispersants in minute quantities and their effect must not be discounted. A perfume can occasionally act as a solvent for the complex and upset a carefully achieved balance. In developing or changing such formulations as these, every new factor introduced, no matter how minute, must immediately be checked for its effect on the color yield of the product. For these reasons, the translation from laboratory to production size batches is often a tedious operation requiring several intermediate pilot size steps to determine all the variables. GENERAL CONSIDERATIONS The major problem of the hair dye formulatot is that he must give a uniform coloration to an unbelievably nonuniGrm fiber. Generally speaking, he cannot do it with a simple all-covering coat of paint-like pig- ment because such a procedure gives dull, solid looking shades which do not appear natural. Working, therefore, with processes which are primarily chemical in nature rather than physical, he finds to his dismay that while many of the things women do to their hair change its chemical properties, unfortunately they are not done homogeneously. Thus, permanent waves are applied only to some strands of hair, and then often only to the ends of these particular strands. Bleaching is done over-all the first few times but the ends of the hair are inevitably more bleach-damaged than the roots. This is due to natural growth, to overlapping subsequent opera- tions and because the ends of the hair get most of the natural bleaching from sunlight. Cationic creme rinses are generally applied uniformly and their effects are not cumulative due to the weekly anionic shampoo, but women occasionally use them pure as a pomade--only on the outer top areas which they can reach easily of course! Our typical customer may have used your competitor's dye product, gotten stains on her face, and tried to use "Clorox" to remove them, thus incidentally chlorinating some of the nearby strands of hair. Perhaps her husband is feeding her arsenic, or perhaps she is pregnant and taking iron pills, or perhaps she just likes to swim in the ocean, but somehow she has gotten a lot of heavy metals in her hair, inactivating the cysteine and later catalyzing various disasterous occurrences when she uses hair products. Any of the above rather common occurrences will affect the color uptake by the hair from dye solutions. Since any combination of them in any de- gree is likely to have occurred, and since the customer is further likely to use any of your shades on any color hair she may have, the possibilities in favor of something going wrong are staggering. There is no such thing as normal hair except in the hair dye formulator's book of shade samples and in the Pollyanna-like direction booklets accompanying the product on the market.

306 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS There are several ways out of this dilemma. One is to market a product which gives little or no color, yet looks colored and gives a beautiful sheen so that the customer is convinced that she has achieved the promised "color highlights." Another is to limit the product primarily to profes- sional use so that only persons skilled in the art will apply it. l,ess de- sirable is to damage the hair uniformly, pretreating it by some process such as a peroxide bleach. The soundest approach however seems to be the application of a light transparent color film which allows a natural sheen to reflect from the hair, which does not rub off, which can be and is completely removed •¾om the hair with each shampoo. Thus, each application starts from scratch and always gives the same result to the same woman. Such a product, unaf- fected by the chemical reactivity of the hail if properly formulated, can be made by using anion-cation color complexes. At present, it seenas the ideal basis for formulating home-use temporary hair colorings. REFERENCES (1) Den Beste, Marion J., U.S. Patent No. 2,643,211 (1953). (2) Monsavon L'Oreal, British Patent No. 741,307 (1955). (3) Diserens, Louis, "The Chemical Technology of Dyeing and Printing," Vol. II, transla- tion by Wengraf and Baumer of 2rid German edition, New York, Reinhold Publishing Corp. (1951), 32-33. (4) Diserens, Louis, Ibid., 101-103. (5) Diserens, Louis, Ibid., 315-319. (6) Diserens, Louis, Ibid., 323. (7) Harry, Ralph G., "Cosmetics--Their Principles and Practices," 1st U.S. edition, New York, Chemical Publishing Co. (1956), p. 484. (8) Harry, Ralph G., Ibid., 489-498. (9) British Patent No. 435,431 (1953) German Patent No. 673,158 French Patent No. 770,235. (10) Geigy Chemical Corp., "Sequestrene," technical bulletin (1952), 44. (l 1) Karrer, Paul, "Organic Chemistry," 3rd ed., New York, Elsevier Press, Inc. (1947), p. 475. (12) Kass, G. S., ztm. Pe•f. ztromatics, 68, (1), 25 (2), 34 (3), 47 (1956) (13) Ferber, K. H., Dyestuffs, National Aniline Div., Allied Chemic•{1 and •)ye Corp. (March 1957). (14) Karrholm, M., and Lindberg, J., Textile Research •7., 26, 528 (1956). (15) Widner, W., Buehler, A., and Roesti, H., U.S. Patent No. 0.,602.722 (1952). (16) Wittwer, Robert, U.S. Patent No. 2,585,610 (1952). (17) Seemuller, J. R., U.S. Patent No. 2,848,369 (1958). (18) Kritchevsky, Wolf, U.S. Patent No. 2,116,521 (1938). (19) Schlack, Paul, U.S. Patent No. 2,131,145 (1938). (20) Kritchevsky, Wolf, U.S. Patent No. 2,163,043 (1939). (21) Kritchevsky, Wolf, U.S. Patent No. 2,185,467 (1940). (22) Brown, A. E., U.S. Patent No. 2,717,228 (1955). (23) Orelup, J. W., U.S. Patent No. 2,208,594 (1940). (24) ¸relup, J. W., U.S. Patent No. 2,359,783 (1944). (25) Charle, R., U.S. Patent No. 52,695,259 (1954). (26) Norland, E., British Patent No. 799,458 (1958). (27) Den Beste, Marion J., U.S. Patent No. 2,763,269 (! 956). (28) Donker, Dirk J., Dutch Patent No. 68,372 (1951). (29) Samuel, Ruth, and Wotzilka, Minna, U.S. Patent No. 2,577,921 (1951). (30) Alexander, P., and Hudson, R. F., "Wool--Its Chemistry and Physics," 1st edition, New York, Reinhold Publishing Corp. (1954), pp. 232-233. (31) Deadman, L. L. F., British Patent No. 721,831 (1955).