It depends on which red we are talking about. The artificial pigment was originally a shimmer that washed out super fast. To avoid that, labs now formulate it as a base (blonde, chestnut… the color that stays), so it's super tenacious. As for the red-orange that appears when you lighten the hair, we call it the lightening background. A natural hair color is made up of red, blue and yellow pigments. Oxidation removes blue and yellow first, which explains why lightened hair can appear a little red. To completely get rid of red (artificial or lightening background), several options:1/ use all three repigmenting care shampoos with “cold” reflections (blue or purple formulas); 2/ ask a colorist to counter the warm reflection with a cold reflection patina; 3/ completely bleach the hair and recolor it.
White hair is devoid of melanin. To color it, you have to enter the structure of the fiber (=open the scales) and load it to death with pigments. In addition, the coloring fades more quickly than on hair that still has melanin. If you have little white hair, you camouflage them in the hair with a scan. If you have a lot, it's better to color all the hair, knowing that the color fades faster at the root. Then, we just touch up the roots, so as not to overload the lengths (they would be much darker than the roots). The good idea, even if you do your color at home:go to a salon from time to time so that a pro harmonizes roots and lengths.
Thanks to Frédéric Mennetrier, colorist at Atelier Blanc and L'Oréal Professionnel expert, Rodolphe Lombard, colorist at the Salon Couleurs par Rodolphe and David Merveille, Schwarzkopf consultant hairdresser.
