380 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS moderate resistance to shampooing and by the fact that hydrogen perox- ide is never used in their application. The main prerequisite ot5 a tem- porary color is that it be completely removed with one shampooing there- fore, penetration of the hair is not desirable. Dyes that are in their final colored form are used in temporary colors. They are generally applied to shampooed hair that has been towel-dried and is then set and dried with- out rinsing. In this paper only the semipermanent colors are considered. First, the types of dyestuff that have been suggested will be discussed, with references describing their methods of application. Then a testing method, for determining the suitability of dyes for semipermanent hair coloring, will be proposed. Next, the preparation, application, and test- ing of a series ot5 indophenol and indamine dyes will be described. Heald (1) has published an excellent review of the patents issued in this field prior to 1962. A study of this paper and of the current literature reveals that many classes of dyes have been proposed for use in semipermanent hair coloring. Since the patents in this field are much too numerous to mention, only a few of the more recent ones, for each class of dye and dyeing assistant, will be listed. DYESTUFFS USED IN SEMIPERMANENT HAIR COLORS Oxidation Dyes There are two classes of dyes, which are also used in the oxidation colors, that are applied as semipermanent colors without the addition of an oxidizing agent. The first of these comprises the nitro dyes which in- clude nitro-p-phenylenediamine (a red shade) and nitro-o-phenylenedi- amine (a bright yellow). Much work has been done on improving the solubility, increasing the substantivity, and/or modifying the color by replacing one or both of the hydrogens on the amino groups with ali- phatic or quaternary ammoninm radicals. Since 1934, 13 U.S. patents and 12 British patents have been issued on this modification. Four of the most recent of these patents are listed in the references (2-5). The second of these classes consists ot5 oxidation dye intermediates that are developed by atmospheric oxidation. These include polyamino- phenol compounds such as 2,4,6-triaminophenol and its derivatives (6). They are applied to hair from a 3% aqueous solution which has been adjusted to a pH of 8 just prior to application and are oxidized to their colored forms by a 15-min contact with air. In another method (7), the n itrogen-methylated or oxygen-methylated 1,2,4-trisubstituted benzenes,

C()LORING WiTH SEMIl'ERMANENT DYES 381 such as 4-methoxycatechol, are applied from a 1% solution at a pH of 7. In still another method (8), 1,2,4-trihydroxybenzene is applied from a 2% aqueous alkaline solution. In a recent U.S. patent (9), the use of 2,5-di- hydroxymonoethylaminobenzene is revealed. A cid Dyes Acid dyes, that were developed for the textile industry and are being used for semipermanent hair coloring, include regular acid dyes, metal- lized dyes, and chrome colors. The regular acid dyes include azo dyes (10), anthraquinone dyes (11), azine, xanthene, and triphenylmethane- type dyes (12). Acid dyes are generally applied from an aqueous solution at a pH range from 2.5 to 4.0 but in one of the patents cited above (11), a pH range of 8.0 to 10.0 is used for dyeing with aliphatic amine deriva- tives of anthraquinone dyes. There are two types of metallized dyes that are being used as semi- permanent hair colors. One of these, of which the Irgalan* dyes are typical, contains one atom of metal for every two moles of dye and is classed as the neutral-dyeing type. The other, to which the Neolan* colors belong, contains one atom of metal for each mole of dye and is classed as the acid-dyeing type. These dyes are applied from a 1% aque- ous solution at a pH around 4.0 (12). Chrome dyes, when used as semipermanent hair colors, are generally applied as acid dyes without treatment with any metal salt (12). The color differs from that produced by the same dye when used with chrome but some of the dyes of this series have sufficient fastness properties to be satisfactory when applied in this way. Color Index Mordant Black No. 26 which gives a purple shade of good fastness is an example. Basic Dyes When basic dyes are used in semipermanent hair colors they must be carefully selected in order to achieve satisfactory fastness properties and minimum staining of the scalp. A method for using triphenylmethane, azine, oxazine, and thiazine basic dyes at a pH of 7 to 8, in the presence of an oil, a cationic surface active material, and a thickening agent, is de- scribed in a recent U. $. patent (13). The use of basic azo and anthra- quinone dyes, containing a quaternary ammonium group, is described in a British patent (14). * Geigy Dyestuffs, Saw Mill River Road, Ardsley, N.Y. 10502. t Ciba Chemical & Dye Co., Fair Lawn, N.J. 07410.