Bleach and Highlights Breakage: Before and After Colouring Care

The short answer: bleach lightens hair by breaking down its pigment, and it can’t do that without also weakening the protein around it. Breakage after highlights is usually the result of too much lightening in one sitting, overlapping bleach on hair that was already done, or harsh care in the weeks after. A strand test, a patch test, spaced appointments and gentle aftercare prevent most of it.

Going from dark brown to caramel highlights is one of the most requested changes in salons across Pakistan and India, and because most South Asian hair starts very dark, packed with pigment, it takes far more lightening to reach a golden shade than it would on light brown hair. More lightening, more stress. Here’s what’s happening, and how to protect your hair before and after colouring. This belongs to our Hair Care series.

Why bleach weakens hair

Hair colour comes from melanin, tiny pigment grains inside the cortex (the thick middle layer of the strand), and bleach is usually hydrogen peroxide made stronger by an alkaline booster so it can reach them. The alkali swells the hair and lifts the outer cuticle like opening shutters. The peroxide then gets inside and oxidises the melanin, which is what makes it fade.

The same chemistry also attacks some of the bonds that hold keratin together, especially the sulphur bridges (disulphide bonds) that give hair its strength and spring, and while a healthy strand can survive a fair amount of this, there is a limit that nobody can see coming from the outside. Then it snaps. Push past it, and the hair turns stretchy when wet and rough when dry.

So it’s a trade. Every level lighter costs strength.

Strand test and patch test: two different jobs

People mix these up. You need both.

• The patch test checks your skin. A small dab of the dye mixture goes behind the ear or on the inner elbow and stays there, dry, for 48 hours. Any itching, redness, swelling or rash means don’t colour. Permanent dyes and some toners contain PPD and related chemicals that can cause serious allergy. Our detailed guide to hair dye allergy and PPD explains the reactions and safer options.
• The strand test checks your hair. A thin section from underneath is lightened on its own. You see the real result, how long it takes, and whether the hair turns gummy or snaps when gently pulled. If it does, the full head will too.

A good colourist will offer both without being asked, and if a salon tells you “our brand doesn’t need a patch test” or “you’ve coloured before, so you’re fine”, walk out, because allergy to hair dye can develop after years of trouble-free use and the next reaction may be much worse than the last. Walk out.

How to get lighter without wrecking your hair

1. Two weeks before: stop heat styling where you can, use a moisturising conditioner every wash, and get a light trim of dry ends.
2. 48 hours before: do the patch test. Also tell the colourist about henna, black mehndi, box dye or keratin treatments in the last year. Henna with metallic salts can react badly with bleach.
3. The day before: don’t scrub your scalp or shampoo hard. A little natural scalp oil acts as a buffer.
4. At the salon: ask for a strand test and a realistic target. From very dark hair, two or three levels lighter in one session is a gentler goal than going straight to blonde.
5. During: bleach should go on new growth only for a root touch-up, not pulled over previously lightened lengths.
6. After: wait 48 to 72 hours before the first shampoo, then wash with lukewarm water and a mild shampoo, and condition every time.
7. Next session: space lightening 6 to 8 weeks apart. Toners and glosses in between are gentler than more bleach.

Bond-building products, honestly

Bond builders are added to bleach at the salon or used as a treatment afterwards, and they aim to protect or reconnect some of the bonds that bleach breaks, so used properly they can make hair less brittle and cut breakage, which is why many colourists won’t lighten without them now. That’s real.

The honest limit? They don’t turn over-processed hair back into virgin hair, and they don’t make it safe to bleach again and again. Treat them as a helmet, useful, but you still shouldn’t crash. Home “bond repair” treatments can help with feel and manageability; a deep conditioner and a regular trim do much of the same work for less money.

Aftercare in the first eight weeks

• Use conditioner after every wash and a hair mask once a week.
• Detangle wet hair with a wide-tooth comb, from the ends up, very gently. Lightened hair is weakest when wet.
• Turn straighteners and curlers down; bleached hair usually needs 150 to 165 °C at most.
• Sleep with hair in a loose plait, not a tight bun.
• Wear a cap in chlorinated pools; chlorine and sun both dry lightened hair and can shift the tone.
• Skip lemon juice, strong vinegar rinses and “natural lighteners” at home. They dry the hair further.

Myth: bleaching at home is just as safe if you follow the box

Box lighteners come with instructions, and some people do well with them, but the problems usually come from overlapping the product on hair that’s already light, leaving it on “a bit longer to be sure”, or using high-strength developer on the scalp. Salons can see the hair. The box can’t. If you do colour at home, always patch test, always strand test, set a timer, and never bleach eyebrows or eyelashes with hair products.

Questions about bleach and highlights