Colour B4 Hair Colour Remover Extra Strength For Darker Hair Colours. Colour B4 Regular Hair Colour Remover is perfect to wash away your unwanted artificial colour. It is the most convenient and effective way to reverse an undesirable hair colour application. Extra is ideal for the removal of a build up of hair colour or if the colour you want to remove is very dark. Colour B4 shrinks the artificial dye molecules in the hair, enabling you to simply wash them away. Colour B4 does not touch your natural hair pigment so you are left with the colour which lay beneath your artificial shade. Colour B4 contains no bleach or ammonia and the after treatment buffer means you can re-colour your hair immediately after applying Colour B4 and still achieve your desired result. This Product contains ingredients that may cause skin irritation on certain individuals, a patch test is recommended for first time users.