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

386 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Table V Preparation of Dye Dispersions Material Percentage References Dyestuff 0.3 Benzyl alcohol 4.0 Isopropanol 2.0 Miranol SM 3.5 Hydroxy ethyl cellulose 1.2 Water 89.0 28 20 16 2 white hair, by brushing, and left on the hair for 30 min at room tempera- ture. The hair is then rinsed in running water and dried. The following series of nine tests is proposed for determining whether a dye is satisfactory for use in semipermanent hair colors. Substantivity Substantivity, as used in this paper, is described as the amount of color retained by the hair after brush dyeing at room temperature and rinsing thoroughly. The dyed hair is examined for depth of shade and used for subsequent fastness tests. Fastness to Fading in Light This is determined in the usual manner in a standard fadeometer. It has been found that fastness to light of a dye applied at boiling tempera- ture often differs from that of the same dye applied at lower temperature. Examples illustrating this point are given in Table VI. Table VI Dip Dyeing of Hair in 0.1% Aqueous Solution at pH 3.0 Dyeing Temp Dyeing Temp Dye (øC) Fading (hr) (øC) Fading (hr) C.I. Acid Red No. 4 25 24 95-100 6 C.I. Acid Blue No. 168 25 6 95-100 26 In both cases the color produced at the boil was substantially darker than that obtained at room temperature. It is apparent that fastness to light values determined after application of dyes at the boil, as published by dyestuff manufacturers, cannot be accepted as valid for the same dye applied at room temperature. If we accept a light fastness rating of 10 hour-q to be satisfactory for hair dyes applied by brushing at room tern-