Sodium Laureth Sulfate (SLES) as an anionic surfactant, and a solvent for some ingredients. It is one of the most effective surfactants in our Shampoos to clean the skin and hair by helping water to mix with oil and dirt so that they can be rinsed away. The reason for SLES in hair colorants is to build and stabilize the emulsion. The better an emulsion is stabilized, the lower the chance to cause irritation. It also helps to dissolve dyes and it also helps to rinse the cream off of the scalp. In the case of hair colorant tints the SLES combines the waxes like Cetearyl Alcohol with the water to ensure a nicely spreadable mixture which is easy to use without dripping.