The first number is the depth: how light or dark the shade is. The number after the slash is the tone: how warm or cool it looks. In our blonde range, 7 is a medium blonde, 8 is a light blonde and 9 is the lightest. After the slash, 0 is natural, 1 is ash, 3 is golden, 4 is copper and 43 is red copper. So Light Golden Blonde 8/3 is a light blonde with a warm, golden finish, while Medium Ash Blonde 7/1 is a medium blonde with a cool one.

These are the names a professional hair colourist uses, so a shade can look a little deeper at home than the name suggests. H2O Water Colour isn't mixed with peroxide, so it won't lift your hair lighter the way a mainstream tint does. A shade we call Deep Dark Blonde in the salon (6/0) is what most people at home would call light brown. Every shade shown is how it looks over blonde or grey hair. For a true blonde effect from brown hair, you need a colour mixed with peroxide.

Both, depending on how much grey you have and the shade you choose. H2O Water Colour deposits a soft, tinted gloss through grey, so results look natural rather than flat or solid. On lighter or evenly grey hair, coverage looks fuller. On darker hair with scattered greys, it reads more as a gentle, lit-from-within blend, almost like a natural highlight. Because there's no lift, regrowth softens in rather than forming a hard line, and the rest of your hair stays exactly as it is.

In the salon, we often use our lighter shades on blonde hair for clients who don't want their grey to come through as dark as their natural colour but it won't turn brown hair blonde.

They're formulated with sensitivity in mind. Every shade is 95% water-based and free from ammonia, peroxide and resorcinol. The formula is also odourless, which many people with reactive scalps find far more comfortable than a conventional dye. It's still a permanent colour and does contain some of the same permanent-colour ingredients found in most permanent dyes, so a skin test 48 hours before every application is essential, even if you've coloured with us before.