A guide to hair colour

Whether you colour at home or in a salon, it helps to know what each type of colour does, how long it lasts and what it can and can't achieve on your hair.

Types of colour

• Temporary colour (sprays, chalks, coloured masks) coats the outside of the hair and washes out in one to a few washes.
• Semi-permanent colour deposits colour without lightening and fades gradually over several weeks. It is good for adding tone or shine, or for trying a shade out.
• Demi-permanent colour uses a low-strength developer, lasts longer than semi-permanent and can blend grey hair, but doesn't lift natural colour much.
• Permanent colour lightens the natural pigment and deposits new colour inside the hair. It grows out rather than washing out, so you will see roots.
• Bleach (lightener) removes pigment. It is needed for big jumps to lighter shades and for most pastel or vivid colours, and it is the most damaging process if it isn't done carefully.

Common techniques

• All-over colour: one shade from root to tip.
• Highlights and lowlights: fine sections woven into foils, lighter or darker than the base.
• Balayage: colour hand-painted onto the surface of the hair for a softer, more natural grow-out.
• Ombré: a more obvious change from darker roots to lighter ends.
• Toner or gloss: a sheer colour over lightened hair to adjust warmth, for example to calm brassy yellow or orange.

The patch (allergy) test

Hair dye, especially permanent and some demi-permanent dyes, can cause allergic reactions, and in rare cases these are severe. Reactions can develop over time, so you can react to a product you have used before without problems. Most dye manufacturers tell you to do a skin allergy test 48 hours before every application, and reputable salons will ask you to come in for one.

Follow the instructions that come with the product exactly. If you notice itching, burning, redness or swelling, don't colour your hair, and get medical advice if the reaction is more than mild. If your face, lips or eyes swell, or you have difficulty breathing, get emergency help.

A strand test is different: it checks the colour result and how your hair copes, on a small hidden section, before you commit.

What colour can and can't do

• Colour doesn't lighten colour. If your hair is already dyed dark, putting a lighter permanent dye on top won't make it lighter; it usually needs colour removal or bleach, best handled by a professional.
• Very dark to very light in one session is hard on hair. Big changes are often safer spread over several appointments.
• Box dye results vary with your starting colour. The shade on the box is the result on light, undyed hair.
• Henna and some "natural" dyes can react badly with later chemical colour. Tell your colourist about anything you have used.

Last reviewed: November 2026