Hair colorist must take into consideration a few things to formulate color that's perfect for your target color..Here are the basics: 1st what is your natural hair color? Do you have existing color on your hair? What is your desired result? All of the above have a natural remaining pigment we must always think about: Natural Levels 1 thru 5 (black-light brown) has red to red orange remaining pigment when lightening. Levels 6-12 (dark blonde-pale blonde) has orange to yellow remaining pigment. What is natural remaining pigment? Its the tone that shows thru when seen in the light. Coloring hair is not only an art, but there is also science behind the formulation.