What is bond repair and how does it work?
10 min read Hair concerns Updated 5 October 2026 By Anna Sophie Schulenburg
Bond repair is hair care for the inner links of the hair fibre, above all the sulphur bridges that break during bleaching, perms, chemical straightening and frequent heat styling. The active ingredients are small enough to get into the fibre, where they are meant to support the broken points so your lengths snap less often when you comb and blow-dry. The stretch test further down, done with one wet hair from your brush, shows whether a bond repair treatment at the salon or at home is worth it for you. After the first few washes, watch for two things: whether wet hair gives less like rubber, and whether fewer short pieces stay caught in the comb.
What bond repair does inside the hair
Picture the inside of a hair as many long protein chains lying side by side like the rails of a rope ladder. Rungs hold them together, and there are three kinds. Hydrogen bonds come apart as soon as hair gets wet and close again in the new shape as it dries. That is why a blow-dried wave lasts until the next wash or the next damp day. Salt bonds depend on pH and loosen when a mixture is strongly acidic or strongly alkaline.
The third kind are disulphide bonds, also called sulphur bridges. They link two sulphur-containing building blocks of keratin so firmly that water, shampoo and brushing cannot touch them. They break mainly through chemistry and high heat, and more slowly through a lot of sun. Bleach opens the cuticle with an alkaline mixture and breaks down pigment with hydrogen peroxide. In the process it also oxidises some of the sulphur bridges, and the separated ends do not find each other again on their own. A perm breaks the bridges on purpose and closes them again in the new shape, though far from every one re-forms. Chemical straightening breaks them too, and some never come back. A flat iron gliding hot over the same section several times a week also wears down the keratin over time.
With every missing rung the ladder gets shakier. Wet hair then stretches a long way and gives like chewing gum, while dry hair snaps mid-length when you brush it.
Bond repair works at these broken points. The active ingredients are small molecules or short protein fragments called peptides, which get into the fibre and are meant to attach to open ends. Depending on the product, they are supposed to reconnect separated chains or protect the remaining bridges during bleaching. On the ingredient list you can spot the small molecules by maleic acid compounds such as Maleic Acid or Bis-Aminopropyl Diglycol Dimaleate.
Bond repair, protein treatment and moisture compared
All three turn up in masks for damaged hair, often in the same tube, yet they work in different places.
| Feature | Bond repair | Protein treatment | Moisture care |
|---|---|---|---|
| Works on | The links between the protein chains inside | Rough, porous spots on and in the fibre | The water content of the fibre |
| Typical ingredients | Peptides, maleic acid compounds | Hydrolysed keratin, wheat, silk or rice protein | Glycerin, panthenol, aloe vera |
| What you notice | Wet hair gives less, less snaps off when you comb | Lengths feel firmer and have more grip | Lengths turn soft and supple |
| When it's too much | Rich creams weigh fine hair down | Lengths turn hard and straw-like and snap more easily | Lengths hang limp and hold no shape |
| Suits | Bleached, coloured, chemically treated hair | Porous hair that loses moisture fast | Dry, rough hair that still stretches well |
A protein treatment lays protein into the gaps in the fibre, a bit like filler in hairline cracks. It washes out over the weeks and leaves the inner links unchanged. Bond repair aims at those links themselves. On bleached hair the two complement each other, and every head of hair needs moisture anyway. Whether your lengths are getting too much or too little protein right now shows in the balance between protein and moisture in your hair.
What bond repair can and cannot do
Bond repair is cosmetics, and “repair” on a bottle means something more modest than it does in a workshop. At best you notice wet hair that springs back better after stretching, less breakage when you detangle and lengths that feel smoother. A bond additive in the bleach mixture is also meant to make less hair snap during lightening.
What no bond care manages: rebuilding a worn-away cuticle, sealing split ends or putting bleached hair back to how it was before bleaching. At the root, meaning growth and density, it does nothing at all. And care from a tube washes out over time. That is why it belongs in your hair regularly for as long as the damaged lengths are there.
That bleach breaks sulphur bridges is well researched. What remains open is how many of them a bond product actually closes again and how long that lasts after several washes. Published measurements come mostly from the manufacturers themselves, and for some active ingredients the exact mode of action is disputed. What you can check yourself is how your hair behaves when stretched and how many broken pieces are caught in the comb.
Do you need bond repair? The stretch test
Bond care does the most for lengths that are bleached, lightened with highlights or balayage, coloured repeatedly, permed or chemically straightened, and for hair that goes under the flat iron several times a week. A simple test shows whether your lengths are among them.
Take a long hair from your brush that came out while you were combing. Wet it, hold a piece from the lengths between the thumb and index finger of both hands about five centimetres apart, and pull slowly. Leave out the end nearest the root, as the hair there is usually still untreated. Test two or three hairs, because a single one can mislead.
| What the wet hair does | What it means | What helps |
|---|---|---|
| Stretches a little and springs back | The inner links are holding | Your usual care, bond repair adds little |
| Stretches far like chewing gum, stays long or snaps only late | Many inner links are missing | Bond repair, plus protein in a small dose |
| Snaps straight away, with almost no stretch | The fibre is dry and stiff | Moisture first, pause protein treatments |
| Stretches normally but feels rough once dry | The cuticle is roughened | Conditioner and leave-in, bond repair as needed |
Bleached lengths also need the basics, such as a mild shampoo, a flat iron that starts at 150 °C and the other rules for caring for bleached hair. Does your hair fit no row clearly, or do two apply? The free hair analysis asks about treatments, heat and hair structure one by one.
Bond repair treatment at the salon or at home
At the salon the bond builder usually goes straight into the bleach or colour mixture. It is meant to protect the sulphur bridges while the lightening is under way, because most of the damage happens in those minutes. So before every lightening appointment, ask whether a bond additive goes into the mixture. After rinsing there is often a second, concentrated step as a treatment. This is meant to make bleaching kinder to the fibre. Several levels of lift in one appointment still put it under heavy strain.
At home, bond care comes as shampoo, conditioner, mask and leave-in. Shampoo and conditioner stay in the hair for seconds to a few minutes, a mask works for several minutes, and a leave-in stays until the next wash. For visibly damaged lengths, what counts most is whatever is left on or stays in. The salon additive protects during lightening, and home care carries you through the weeks until the next appointment.
How to use bond care at home
Step 1 — Wash. Shampoo on the scalp only, letting the lather run through the lengths as you rinse. A bond shampoo is fine to use without being essential, as it only stays in the hair briefly.
Step 2 — Leave a mask on. Once a week after shampooing, apply a bond mask to towel-dried hair from ear level down: hazelnut-sized for chin-length hair, walnut-sized for shoulder-length and two walnuts for chest-length. Stick to the time on the pack, as leaving it longer adds nothing. Rinse thoroughly, then use your conditioner as usual.
Step 3 — Apply a leave-in. After every wash, use a pea-sized amount for chin-length hair, two for shoulder-length and three for chest-length. Rub the leave-in between your palms, scrunch it into the mid-lengths and ends and keep it off the roots. Then comb through with a wide-tooth comb, working up from the ends.
Step 4 — Protect from heat. Heat protectant goes on over the leave-in. Blow-dry on a medium setting at 15 cm, start the flat iron at 150 °C and give each section one pass.
If you have sensitive skin, apply a new product to a coin-sized patch in the crook of your elbow first and wait 24 hours. Masks and leave-ins don't belong on the scalp anyway.
After the first wash, check whether the comb glides through the wet lengths without catching. After four weeks, repeat the stretch test with a fresh hair and look into the basin after combing. Fewer short, broken pieces and hair that springs back when wet are reasons to keep going. If your lengths feel hard and straw-like instead, that points to too much protein, because many bond products also contain proteins. Drop the mask for two weeks and use a moisture mask in the meantime.
The most common mistakes and what to do instead:
- Mask and leave-in on the roots → only into the lengths from ear level
- Stopping after a week because nothing happens → use it for four weeks, then compare with the stretch test
- Leave-in instead of heat protectant → leave-in first, then heat protectant
- Stacking bond mask, protein mask and leave-in every day → one mask a week, the leave-in after every wash
Who can skip bond repair
Hair that has never been bleached, permed or chemically straightened and springs back in the stretch test has few broken sulphur bridges. A good conditioner helps it more than a bond product. If only the ends are dry and rough, what is missing is moisture.
No care closes split ends for good; they have to be cut off. How far the scissors need to go at your next appointment depends on how well you prevent split ends and breakage. If a hair that has fallen out has a pale bulb at its end, it came out at the root and did not break off. A few such hairs are part of normal shedding, and care in the lengths does nothing against more of them. Knowing how to tell hair breakage from hair loss therefore decides whether your lengths are the right place to work on at all. If your hair suddenly falls out in clumps or in round patches, see a dermatologist, because the cause may then lie inside the body.
If you use MONAT
At MONAT the line for damaged, breakage-prone hair is called Bond IQ™. For home use the key product is the Bond IQ™ Peptide Therapy Leave-In Cream, because it stays in the mid-lengths and ends until the next wash. It is meant to make the lengths easier to comb and protect them from avoidable breakage during styling. It does not seal split ends, and it does not replace heat protection either. The strengthening Bond IQ™ Shampoo is the basis of the wash, though it only stays in the hair briefly. How much of each to use for your hair length is covered in how to use Bond IQ™. For visible split ends there is REJUVABEADS®, a finish that makes the ends look smoother for a while. Brittle lengths call for the ongoing care, forked ends for the finish, and if you have both you can combine Bond IQ™ and REJUVABEADS®.
What care can do
Support cleansing, conditioning, manageability, shine, frizz control, protection from avoidable breakage and a fuller-looking appearance, depending on the product and its substantiated claims.
What it cannot do
Diagnose disease, correct hormonal causes, create new follicles or permanently fuse fully split hair ends.
Right away
Right after use, the lengths feel softer and smoother and comb more easily.
With continued use
With regular use, stressed hair can look more resilient over a few weeks, so avoidable breakage goes down.
What it can't do
Bond care is cosmetic: it doesn't stimulate growth and doesn't seal ends that have already split; only a cut removes those.
Quick questions
What does bond repair mean?
Literally, repairing the bonds. The term covers care that works on the links between the protein chains in hair, above all the sulphur bridges. Packaging also calls it “bond builder” or “bond care”.
How soon after bleaching can I use bond care?
From the first wash afterwards. At the salon the first step often goes into the bleach mixture and the second straight after rinsing, and at home you carry on with a mask and a leave-in.
Can I colour my hair after a bond repair treatment?
Yes. Tell your hairdresser beforehand which care you use. Residue from leave-in and mask can make the colour take unevenly, and she then decides whether you should wash your hair the day before.
Is bond repair suitable for curly hair?
Yes. Curls break more easily at their bends than straight hair does, and lightened curls even more so. If your curls droop under creams, choose a lighter texture and scrunch the leave-in into wet hair instead of combing it through.
The free hair analysis sorts out whether your lengths need bond repair, more protein or mainly moisture, based on your answers about bleaching, heat and hair structure.