Back to ingredients list N,N-Bis(2-Hydroxyethyl)-p-Phenylenediamine Sulfate N,N-Bis(2-Hydroxyethyl)-p-Phenylenediamine Sulfate (N,N-Bis for short) forms all nuances of blue and violet, depending on the couplers used, yet it provides a light and sheer color result. Previous ingredientNext ingredient