Oftentimes, returning to your natural color takes several sessions with a colorist unless you're planning to let your hair grow out. However, hair growth happens at about a half-inch per month, so growing out your hair could take a long time, especially if you don't have short hair.

• Permanent colour As the process opens up the hair shaft it's able to embed the dye deep within it, completely changing the colour of your hair, permanently, until that hair grows out.

If you've recently dyed your tresses, we recommend waiting at least a week in between coloring your hair and going swimming. The longer you wait, the more time the cuticles have to close and lock the color inside your strands. So hold off if you can, or protect your hair with a waterproof swim cap!

Permanent hair color uses ammonia to permanently change the melanin—a.k.a. pigment—in your natural hair color. It's mixed with a developer to open the hair cuticles on the surface of the hair; when the cuticles close, the color remains.