Colour Undo reverses the hair colouring process. A permanent hair colour works by depositing small artificial pigment molecules inside the hair. Colour Undo works by reversing the colour process. Colour Undo shrinks the artificial colour molecules and washes them from the hair, revealing the lightest, previous shade. This shade may be lighter than the natural colour, as bleach and ammonia from previous colour treatments may have lightened the natural pigment. Not tested on animals and is Vegan. Please Note: Colour Undo unfortunately does not work on direct or temporary dyes such as Crazy Color. Single Application Box contains: 1 x Activator 60ml 1 x Remover 60ml 1 x Buffer 60ml 1 x Pair of gloves 1 x Instruction leaflet