EFFECT OF CELLULOSE POLYMERS ON DYE UPTAKE 107 charge and molecular weight (1,5). Alternatively, we have studied two different non- ionic polymers: hydroxyethylcellulose (250) and cetil hydroxyethylcellulose (PLUS). The primary binding of these molecules to hair is, mainly, by polar and Van der Waals interactions, and generally they are not highly substantive to hair (1). While 30M and 250 have been well known and used in the cosmetic market over these last thirty years, SL-60 and PLUS are relatively new products. The formulas of the studied polymers are reported in Table II. As a control we have used yak hair colored with a base dyebath in which no polymers were present. EXPERIMENTAL MATERIALS The semipermanent direct dyes reported in Table I were a generous gift of James Robinson Ltd. (England) and of Ciba (Italy), and were used without further purification. Polyquaternium 10 and Polyquaternium 67 were purchased from Dow Chemical Com- pany hydroxyethylcellulose and cetil hydroxyethylcellulose were purchased from the Aqualon Company, Wilmington, DE. The surfactant mixture composed of Laureth-8, cocotrimonium chloride, butoxyethanol, PEG-7 glyceryl cocoate, and Quaternium-80 was purchased from LCW, and bi-distillate water (UPP) was purchased from Fluka and Carlo Erba. All these reagents were used as received. A buffer solution at pH 6.0 was prepared from distilled water with the addition of 2-amino-2-methyl-propanol (3.5% w/w). A regular cleaning shampoo containing so- dium laureth sulfate, sodium chloride, sodium lauryl sulfate, and lauryl glucoside was used during the washing procedure. Yak hair samples, obtained from So. Cap (Naples), were used throughout this work as test fibers. The average diameter was determined microscopically using 20 specimens, and a value of 70 ± 1 µm, 95 % confidence limit, was obtained. All tresses used were 4-5 cm in length and each tress was 0.15 mg in weight. DYEING EXPERIMENTS Preparation of dyeing solution. A base dye bath composmon ( control) was prepared by mixing 0.5% ofHC Blue 2, 0.5% of Basic Red 51, and 0.5% ofHC Yellow 2 with 10% solvariane mixture and 88.5% distilled water. In a first step, Solvariane and 20% of the total water amount were mixed and kept under stirring at room temperature for 15 min until a homogeneous solution was obtained. Successively, all the dyes were added and the mixture was kept under stirring at 60 ± 1 ° C for 2 hr until complete dissolution of the dyes. After 2 hr, the rest of the water was added and the solution was kept under stirring at room temperature for more than 3 hr. Finally, the pH of the resulting dyebath was corrected to 6.0 with the addition of 2-amino-2-methyl-propanol. For the preparation of the dyebath containing polymer, 0.1 % of the chosen polymer was added to the base bath composition. The polymer was first dissolved in distillated water previously warmed to 50° ± 1 ° C and kept under stirring for 2 hr. The mixed dye solution, obtained as described previously, was then added, and the resulting solution

108 JOURNAL OF COSMETIC SCIENCE Table II Cellulose Polymer Formulas 30M R' = CHrCHrOH R= CHrCHOH-CHrN(CH1h SL-60 n 250 PLUS