Temporary hair dye changes hair colour instantly by coating the hair with colour. It is often in the form of a chalk, powder or spray. It will not lighten or darken the actual hair colour. Temporary colour is used to conceal re-growth, cover grey hair or add panels of colour. Temporary hair dye washes out with shampoo. Because of its ability to quickly add colour and rinse out, temporary hair colour is ideal for quick fixes or experimentations.