The chemicals in “permanent” hair dyes react with hydrogen peroxide within the hair. These dyes won’t wash out, but due to new hair growth you will usually have to re-colour after 4 to 6 weeks, especially if you’re covering gray hair. New innovative products can now colour your hair in as little as 10 minutes! Since some people are allergic to the chemicals contained in hair dyes, it’s a good idea to pre-test a small amount of the product to avoid a reaction and to make certain that it’s the shade you want. Remember, hair colour looks different depending on the surrounding environment (lighting, background colour, etc.), so when you’re selecting a shade, make sure to keep this in mind.
