Permanent or oxidative hair dyes change the colour of the hair permanently in one application and also cover grey hair.
Oxidation dyes or permanent dyes are characterised by their durability, total coverage of grey hair and their simple and safe application. They are the most commonly used dyes by professionals.
The cosmetic active ingredients penetrate the cortex through the scales of the cuticles and need an oxidant and an alkali for the chemical reactions to take place that will give rise to the colour.
Permanent dyes do not wash out and, as the name suggests, remain in the hair. You only need to reapply dye to the roots as your hair grows.