• Question: how does hair dye change your hair colour?

    Asked by Steven to Andy, Dwaine, Natt, Priya, Tatiana on 19 Jun 2015.
    • Photo: Natt Day

      Natt Day answered on 19 Jun 2015:

      Hi Steven,

      There are several different types of hair dye– and they all work in slightly different ways– so I’m just going to focus on the two most commonly used types of dye: permanent and semi-permanent dyes.

      Permanent dyes tend to use a chemical reaction between the dye (which often contains ammonia and peroxide) and the keratin that makes up your hair. The molecules of ammonia and peroxide are small enough that they can enter your hair strand and once in the strand the oxidation reaction occurs– producing a molecule that is much larger and is bound to the hair, so it cannot be washed out.

      Semi-permanent dyes have small colour molecules that will enter the hair strand and coat it– giving the appearance of a new colour. However there is no reaction and so the colour molecules remain small, hence why these dyes wash out and shouldn’t leave any long-term colour changes to the strands.

      Natt

Comments