Colourstart is a unique patch test used by hairdressers as a skin allergy test. These tests help the hairdresser to check if clients are likely to have a problem with hair dye. The alternative is often unpopular and impractical for clients. Colourstart is used on clients who do not have time to visit the salon 48 hours before every application. It is used on clients who do not want hair dye left open on their skin.