50 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS 30 -O O-- 2O 0 10 20 Ag Content (wt%) Figure 2. The L value produced by coloring with Ag-zeolites containing various contents of silver. 10% Hamamelis extract was used for pre-treatment. The hair tresses were dyed for 30 min in 0.1% PPDA solutions in which 0.2 g of each Ag-zeolite was suspended. The coloring effect depends on the concentration of PPDA, the treatment time in PPDA solution, the content of Ag-zeolite, and the hamamelis extract. In these experi- ments, Ag-zeolite containing 10 wt% of silver was used. The effect of PPDA concentration on coloring is shown in Figure 3. Hair tresses were pre-treated in the 25 % hamamelis extract and colored in 8 ml of various concentrations of PPDA solution in which 0.2 g Ag-zeolite was suspended. The coloring effect in- creased with PPDA concentration, but it leveled off above 0.5%. The effect of PPDA-treatment time on coloring is shown in Figure 4. It is shown that the longer the treatment time in PPDA solution, the more effective the hair coloring. The effect of Ag-zeolite is shown in Figure 5. The experiments were carried out at 25øC and 37øC. The color became dark with increasing Ag-zeolite content up to 1.0 g/8 mi. The coloring effect actually decreased above this point. The reason was considered to be that the increase of the solution viscosity with too much zeolite resulted in the decrease of the contact of the coloring solution and hair tress. Coloring at high temperature was shown to be more effective. The effect of hamamelis extract concentration in the pre-treatment solution is shown in 30 2O 0%0%. 0 o o I I I 0 0.5 1 .o PPDA Content (wt%) Figure 3. The effect of PPDA concentration on coloring. 25% Hamamelis extract was used for pre-treat- ment. The hair tresses were dyed in PPDA solution-suspended 0.2 g Ag-zeolite containing 10 wt% silver.

HAIR COLORING 51 3O 20 o 1 l0 • • 20 30 ?ime (rain) Figure 4. The effect of the treatment time in PPDA solution on coloring. 25% Hamamelis extract was used for pre-treatment. The treatments were carried out in 0.5% PPDA solution-suspended 0.2 g Ag-zeo- lite containing 10 wt% silver. Figure 6. It was not effective for coloring to use the high-concentration hamamelis solution above 10%. With this high concentration, the concentration of 1,3-buthylene glycol is consequently higher and it is thought to cover the hair surface and inhibit the diffusion of the dye molecules. OBSERVATION OF COLORED HAIR SURFACE The surface of colored hair was observed with SEM (Scanning Electron Microanalyzer X-650, Hitachi, Japan). The hair colored by Ag-zeolite and hamamelis extract was compared with that colored by hydrogen peroxide. While the coloring using hydrogen peroxide results in collapsed scales, that by silver-zeolite with hamamelis extract caused little apparent damage to the fiber surface (Figures 7a,b). SHAMPOO STABILITY The color stability to shampoo treatment is shown in Figure 8. There was little change in color in seven treatments. 40 • 0 : 25'C • • •: 37'C .- 20 •'•' ß • "" 0 0.5 1 .0 A9-Zeoloete Content (c//Smf) Figure 5. The effect of Ag-zeolhe content on coloring. 10• Hamamelis extract was used for pre-rrear- menr. The various amounts of Ag-zeolire containing 10 wt• silver were suspended in 8 ml of 0.1 • PPDA solution.