A method for treating and coloring hair comprising un-pigmented hair comprises:(a) Providing a first composition comprising one or more heavy metal ion sequestrants；(b) Applying the first composition to the hair；(c) Providing a second composition comprising one or more weak acids having a pKa from 2.5 to 5；(d) Applying the second composition to the hair；(e) Providing a third composition wherein the third composition comprises one or more direct dyes which are selected from the group consisting of nitro dye, disperse dye, cationic dye, acid dye, basic dye, neutral azo dye and mixtures thereof, wherein the third composition is able to decrease the reflectance of un-pigmented hair in a wavelength range from 530 nm to 670 nm； and(f) Applying the third composition to the hair.
