The hair dyeing guide

The wheel arranges hues in a circle. Colours opposite each other are complementary and cancel out — this is the key to fixing unwanted tones. As hair lifts, it passes through red → orange → yellow → pale yellow, exposing warm pheomelanin. To neutralise, add the wheel opposite: violet kills yellow, blue-green kills orange, green kills red.

• Violet / purple toner → cancels yellow brassiness
• Blue or ash-green → cancels orange
• Green → cancels red
• Warm tones (gold, copper) add richness rather than cancel

Depth is how light or dark a colour is, measured on a 1–10 scale. Your starting level is the single biggest factor in any result, because chemistry can only lift a few levels at a time.

Most professional and box dyes use a two-part number. The first digit is the depth level; the digits after the dot are the tone direction. So 7.3 is a level-7 blonde with a gold tone, and 5.1 is a level-5 ash brown.

Eumelanin gives brown-to-black shades — more means darker hair. Pheomelanin gives red-to-yellow tones and sits in almost everyone; it's the last pigment to leave during lifting, which is why lightened hair pulls warm and brassy.

Natural dyes (henna, indigo, cassia) are plant pigments that deposit a coating around the hair shaft — they don't open the cuticle or lift your natural colour, so the result layers on top of whatever you already have.

Chemical dyes use an oxidative reaction: ammonia or MEA opens the cuticle, hydrogen peroxide lifts your natural pigment, and dye molecules form inside the cortex. That's why they can lighten, cover grey evenly, and produce a precise, repeatable shade.

• You want to deepen, warm, or add richness without lightening
• Your hair is fragile or already processed and you want to avoid more stress
• You're sensitive to PPD or prefer to avoid ammonia and peroxide
• You like a translucent, multi-tonal, "lived-in" finish

• You want to go lighter, or cover solid grey in one even pass
• You need a precise, predictable, repeatable shade
• You want to neutralise specific warmth (ash, violet toners)
• You're happy to patch-test and follow aftercare to manage the trade-off

Some products sold as henna are blended with metallic salts or PPD. These can react badly if you later apply chemical dye or bleach over them — causing green tones, uneven results, or damage. Check the ingredient list: pure body-art-quality henna is a single plant powder with nothing added.

Pigment coats the outside of the cuticle and washes straight out. No developer, no penetration.

Best for: Testing a shade, one-night colour, costume.

Direct dye stains the cuticle and outer cortex. No ammonia, no peroxide — so it can only darken or add tone, never lighten.

Best for: Vivid fashion colours on pre-lightened hair, refreshing faded tone.

Low-strength developer gently opens the cuticle to deposit pigment without lifting natural colour. Grows out with no hard line.

Best for: Blending greys, glossing, tone refresh, going darker.

Ammonia swells the cuticle; peroxide lifts natural melanin then fixes new dye molecules inside the cortex. The only type that fully covers grey or lightens natural hair.

Best for: Full grey coverage, going lighter, long-lasting change.

Bleach powder + developer strips melanin without depositing colour. Must be followed by a toner or gloss. Keep off the scalp for foils/balayage.

Best for: Going more than 3 levels lighter, platinum, pre-lightening for vivid colours.

Developer controls how much you lift. Going darker than your current shade only ever needs 10 vol. Going lighter than 3 levels from already-coloured hair requires bleach — artificial pigment can't be lifted with colour alone.

Don't shampoo for 48–72 hours after dyeing. The cuticle needs time to fully close and lock pigment in; washing too soon is the fastest way to lose depth and tone. When you do wash, use cool water — hot water opens the cuticle and rinses colour out.

• Aim for 2–3 washes a week, not daily.
• Use a sulphate-free, colour-safe shampoo — sulphates strip dye.
• Cool or lukewarm water keeps the cuticle flat and pigment in.
• For vivid semi-permanents, rinse with cold water until it runs clear.

UV fades colour fast, and hot tools accelerate fade and damage. Use a heat protectant before styling, and wear a hat or use a UV hair mist in strong sun. Air-dry where you can.

• Use a colour-safe conditioner every wash.
• Deep-condition with a weekly mask, especially after bleach or permanent dye.
• Bleached hair benefits from a bond-builder (e.g. Olaplex) to rebuild strength.
• Avoid chlorine — it can turn lightened hair green; use a swim cap or pre-rinse with clean water and leave-in conditioner.

Book a root touch-up every 4–6 weeks to avoid a hard regrowth line. Between full colours, a gloss or demi-permanent refreshes tone and shine without further damage. For semi-permanent fashion colours, re-apply every 2–3 weeks or mix a little dye into your conditioner as a top-up.

• Always patch-test 48 hours before, even with a brand you've used.
• Never mix different dye brands or metal bowls.
• Don't dye an irritated or broken scalp.
• Keep bleach off the scalp for foils/balayage.
• If you've had a black henna "tattoo", patch-test extra carefully — cross-reactions are common.