Olaplex, K18 and bond repair treatments: differences and how to choose them
Bleaching, hair color, straighteners, and blow dryers put a strain on hair structure. In recent years, there has been increasing talk of bond repair or bond building, and names like Olaplex and K18 have become very famous. But what do they really do, how do they differ, and how do they fit into a routine? In this guide, we explain everything in simple terms so you can choose the treatment best suited to your hair.
What "bond repair" means, in simple terms
Hair is largely made of keratin, a protein held together by different types of bonds. Among these, the most important for strength are disulfide bridges: you can imagine them as the "rungs" of a ladder that hold the internal structure together. Chemical treatments like bleaching, coloring, and perms, as well as frequent heat, can break some of these bonds. The result is hair that is more fragile, elastic when wet, porous, frizzy, and prone to breakage.
Bond repair treatments work right at this internal level, helping to rebuild damaged bonds. They are different from a traditional nourishing mask, which acts mainly on the surface, making hair soft and easy to detangle. The two approaches are not mutually exclusive; in fact, they work well together.
Olaplex: the numbered system
Olaplex was among the first brands to bring the concept of bond building into salons. Its system is organized by numbers, and each product has a specific role.
In the salon: N°1 and N°2
- N°1 Bond Multiplier: added to the bleach or color mixture to protect bonds during the service.
- N°2 Bond Perfector: applied after the chemical service to continue the repair work.
These are professional products designed for use by hairdressers.
At home: N°0, N°3, N°4, N°5, N°6, N°7
- N°0: an intensive treatment to be applied before N°3 for deeper action.
- N°3 Hair Perfector: the weekly treatment to use before shampooing on damp hair.
- N°4 Shampoo and N°5 Conditioner: the pair for daily maintenance. There is also the N°4P purple version for blondes.
- N°6 Bond Smoother: a leave-in cream to combat frizz.
- N°7 Bonding Oil: a lightweight oil for shine and styling.
To get started, you can choose the Olaplex N°4 + N°5 + N°7 kit, while for blondes, there is the Blonde Enhancer N°4P + N°5P + N°7 kit, which combines care with an anti-yellow effect. You can find the entire range in the Olaplex collection.
K18: the 4-minute leave-in mask
K18 has a different approach: the heart of the line is the K18 Leave-In Molecular Repair Hair Mask, a leave-in mask based on a patented peptide, designed to act inside the hair.
How to use K18
- Wash your hair with shampoo, without using conditioner.
- Towel dry well until excess water is removed.
- Distribute a small amount of the mask through lengths and ends.
- Leave it on for 4 minutes without rinsing.
- Proceed with styling as usual, even with other products.
A very small amount is enough: with very fine hair, if you use too much, there is a risk of weighing it down. To prep your hair, you can combine it with the K18 Peptide Prep Detox Shampoo, designed to remove residue and build-up.
Other professional options
Wellaplex
This is Wella Professionals' bond system. In the salon, N°1 Bond Maker is used during chemical services, followed by N°2 Bond Stabilizer, both available in the Wellaplex Salon Kit. At-home maintenance is done with the Wellaplex N°3 Hair Stabilizer, a treatment to use periodically.
Schwarzkopf Fibre Clinix
Fibre Clinix is a customizable care system: in the salon, the hairdresser combines a base treatment with specific boosters based on needs. For damage from bleaching and chemical stress, there is the Fortify line, which you can also take home with the Fibre Clinix Fortify kit.
Redken Acidic Bonding Concentrate
Redken's line focuses on acidic pH formulas, designed for chemically treated and damaged hair. It is very comprehensive: shampoo, conditioner, serum, quick mask, and leave-in treatment. Two products to watch out for are the Leave-in Treatment and the 5 Min Liquid Mask, which is convenient when you are short on time.
Salon or home?
Salon treatments, like Olaplex N°1-N°2 or Wellaplex N°1-N°2, are primarily used to protect hair during chemical services. If you get frequent bleaching or highlighting, ask your hairdresser to include them: this is when hair is most exposed.
At-home products are instead used to maintain results and support hair between appointments. They do not work miracles on hair ruined by years of treatments, but when used consistently, they help improve its appearance and resistance. Remember that very damaged or broken ends should still be cut.
How to build your routine
- Every wash: a gentle shampoo and conditioner from the same bond repair line or otherwise suitable for treated hair.
- Once a week: an intensive treatment, like Olaplex N°3, Wellaplex N°3, or the K18 mask, following the manufacturer's instructions.
- After washing: a leave-in treatment and, if you use a blow dryer or straightener, always a heat protectant. Here you can find out how to choose the right straightener to reduce heat stress.
- Periodically: a nourishing mask for softness and shine.
You don't need to use five different bond products together: it is better to choose one or two and use them regularly.
Which one to choose?
- You want a complete, proven system with products for every step: Olaplex.
- You have little time and want a single, fast, leave-in treatment: K18.
- Your hairdresser works with Wella and you want to continue at home: Wellaplex N°3.
- You are looking for a complete routine for bleached and damaged hair: Redken Acidic Bonding Concentrate or Fibre Clinix Fortify.
To learn more about the causes of damage and the daily habits that help, read our guide to damaged hair.
Frequently asked questions
Can Olaplex and K18 be used together?
Yes, many people alternate them, for example, using Olaplex N°4 and N°5 for washing and K18 as a treatment. The important thing is not to overload your hair and to follow the instructions for each product.
Are bond repair treatments suitable for all hair types?
They perform best on bleached, colored, or heat-stressed hair. On healthy, untreated hair, the benefit is less noticeable.
How long does it take to see results?
You often notice a difference in softness from the first few applications, but for stronger hair, you need consistency over a few weeks.
Does bond repair replace getting a haircut?
No. It helps strengthen the hair, but split ends and broken lengths can only be removed with a haircut.
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