System and method for on-site formulation of personalized color-maintaining shampoo products for individual users

A method of maintaining an individual's hair color and tone of previously color-treated hair comprising the steps of:

• (1) determining an individual's hair color by visual recognition, wherein the individual's hair is color-treated, and wherein the hair color is selected from the group consisting of black, dark brown, medium brown, light brown, lightest brown, dark blonde, medium blonde, light blonde, very light blonde, and lightest blonde;
• (2) determining an individual's hair tone by visually recognizing the individual's hair tonal base color, wherein the individual's hair is color-treated, and wherein the tonal base color is selected from the group consisting of grey-violet, blue-violet, yellow-beige, brown, blonde, yellow-orange, orange-brown, red-brown, red-violet, blue-red, and violet;
• (3) referring to a chart which comprises two axes, wherein the first axis comprises said hair colors, and wherein the second axis comprises preselected hair tones based upon said hair tonal base colors;
• (4) intersecting the individual's hair color on said first axis with the individual's hair tone on said second axis to determine a color maintenance shampoo formulation, wherein said hair color maintenance conditioner formulation comprises a mixture of at least two prepared hair color maintenance conditioners mixed in volumetric ratios according to said chart;
• (5) mixing said at least two hair color maintenance conditioners in said volumetric ratios;
• and (6) contacting the individual's color-treated hair with the color maintenance conditioner formulation in order to maintain the hair color and tone of previously color-treated hair.