384 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS semipermanent hair coloring. A method has been described in a U.S. patent (25) for the use of certified acid dyes in such a way that the color is claimed to be resistant to shampooing. In this method, use is made of an aqueous solution at a pH of 8.5 to 12.5 with a salt and carrier present. In one example, the aqueous dye solution contains 0.5% D & C Brown No. 1, 3.8% benzyl alcohol, 4.0% sodium sulfate, and 4.0% ammonium hydroxide. Preoxidized Pyridine Compounds A method of dyeing hair with preoxidized pyridine compounds is de- scribed in a recent Canadian patent (26). In one example, the aqueous dye solution contains 1.8% 2,5-diaminopyridine dihydrochloride, 0.8% (25%) ammonia solution, and 0.1% hydrogen peroxide (33%). The so- lution is allowed to react for 10 hours to form the pyridine dyestuff. Thereafter the solution may be filled into packages ready for use. In another example, the oxidized pyridine compound is filtered off, dried, and is then used as a semipermanent dye. Miscellaneous Components In addition to the dyes, the semipermanent coloring solutions contain surface active materials, solvents, thickeners, and often dye carriers or boosters. No attempt is made to list all of these materials but some of the important ones, with references, are listed in Tables I-IV. Table I Surface Active Materials Used in Semipermanent Hair Dyeing Name Type References Triton X-100 Nonionic 20 Tween 80 Nonionic 20 Igepal CO-730 Nonionic 20 Pluronic L-64 Nonionic 16 Sarcosyl L Anionic 16 Triton X-200 Anionic 21 Igepon T-55 Anionic 20 Sodium lauryl sulfate Anionic 20 Arquad 2HT Cationic 16 Cetyl pyridinium bromide Cationic 2 Aromox DMCD Cationic 16 Cetyl trimethylammonium bromide Cationic 13 Miranol SM Amphoteric 16 Deriphat 151 Amphoteric 27

COLORING WITH SEMIPERMANENT DYES Table II Solvents Used in Semipermanent Hair Dyeing 385 Name References Ethanol 21 Isopropanol 20 Propylene glycol 20 Carbitol 12 Table III Thickeners used in Semipermanent Hair Dyeing Name References Sodium carboxymethyl cellulose 20 Methyl cellulose 20 Hydroxyl ethyl cellulose 2 Sodium alginate 20 Cetyl alcohol 15 Carbopal 934 25 Bentonite 18 Acrylic acid allyl sucrose copolymer 2 Table IV Dye Carriers or Boosters used in Semipermanent Dyes Concentration Material (%) References Benzyl alcohol 4 28 Butyl alcohol 10 12 3-Amyloxy-l,2-propanediol 8 29 Tetraethyl urea 3 30 Acrylic acid monomers and derivatives 5 31 METHODS In order to test the suitability of any dye for use as a semipermanent hair color, a method of application must be selected and a method of testing developed. Based upon the current literature, the materials used in preparation of the dye dispersion or solution selected are shown in Table V. The dyestuff is dissolved in the benzyl alcohol by heating. The iso- propanol and Miranol are added to the water and this mixture is added to the benzyl alcohol-dye solution with stirring. Finally, the hydroxyl ethyl cellulose is added slowly, with vigorous stirring, and the stirring is continued until the dispersion is uniform. It is then applied to natural