Molecular and bond repair hair products are all over social media—these 5 are worth your time

If you have any degree of damage to your hair, whether that’s from heat styling, colouring or chemical treatments, you've probably heard about bond repair hair products (i.e. those that repair damage). Several brands, including Olaplex, L’Oreal Professionnel and Redken, offer professional molecular or bond repair treatments that are applied in-salon by your hairdresser. But the at-home options are designed to maintain these results, offering a lower-strength alternative that can be applied in the comfort of your own home. 

This is an incredibly sciencey subject, so we'll really only be getting into a top level of how bond-building products work. What's important to know is that these products are designed to repair damage, so the most dramatic results will be seen in hair that is damaged—they don't boost moisture like some other hair masks, for example. As a beauty editor who tests hot tools like the best hair straighteners for a living and colours her hair, I’ve tried quite a few of the molecular or bond repair hair products on the market. 

While the best results usually come from either a pre-shampoo or leave-in treatment that sit on the hair for an extended period of time, bond-building technology can also be found in shampoos, conditioners and styling products. These are the at-home options that are worth knowing about. 

The best bond hair repair prorducts according to a beauty editor

1. Olaplex No.3 Hair Perfector 

Olaplex is probably the most famous bond-building range. The brand cemented itself as a celebrity go-to within the first few years of launching because it could reduce the damaging effects of major hair colour makeovers in a short space of time.

Without delving into too much of a science lesson, the patented ingredient (meaning it's not in any other formulas), bis-aminopropyl diglycol dimaleate, repairs broken disulphide bonds, which hold the protein of our hair together. “Disulphide bonds get broken down by mechanical, chemical and thermal damage,” says hairdresser and trend forecaster Tom Smith, who is also an Olaplex Artist. 

No.1 and No.2 are the professional strength treatments applied in-salon, while the famous Olaplex No. 3 is the at-home treatment containing this reparative ingredient. "You can get the exact same results from the treatment at home [as the in-salon options], but you might need to leave it on for longer or do more treatments with the No. 3 to get the same effect, and it builds up over time," Smith confirms.

2. Living Proof Triple Bond Complex

I love Living Proof and this is up there with my favourite products from the brand. As well as those all-important covalent bonds, the Triple Bond Complex formula also targets two (temporary) bonds within the hair - hydrogen and ionic - and works to build new bonds. The patent-pending 3D fortifying technology also helps to protect hair against future damage. 

This product is heat-activated, so it does require you to blow dry your hair for it to
work. But I’m a big fan and have been through a few tubes of it—and while the other products in my styling regime of course play a role in the end result, my hair feels great every time I use this. 

3.  K18 Leave-In Molecular Repair Hair Mask

Biotech haircare brand K18 doesn’t class its products as bond-building, rather repairing hair at a molecular level. It also uses its own patented ingredient, the K18PEPTIDE, which reconnects polypeptide chains within the hair as well as disulphide bonds, by mimicking the hair's natural protein structure. According to the brand, this approach "promotes long-term rejuvenation". 

A big plus is that the mask gets to work in four minutes and doesn’t require washing out; the idea is to skip conditioner then apply to damp hair. The downside is that this technology is very pricey, with the mask retailing for £70 for 50ml. But not only does it give my hair noticeable bounce, it’s been a huge hit since it launched in the UK—according to the brand, at one point this mask was selling once every two minutes on Cult Beauty.

Marie Claire's Senior Beauty Editor, Katie Thomas, visits her colourist every six weeks and he recommends K18 to all of his clients. 

4. Redken Acidic Bonding Concentrate 5 Minute Liquid Mask 

A newer addition to the line-up is this mask, which has bond repair benefits in a (surprisingly lightweight) very moisturising formula for a nice all-rounder. It gets to work quickly and I often reach for it instead of conditioner. The leave-in Acidic Perfecting Concentrate Leave-In is also one of my favourite products to apply before drying my hair with a hot brush.

Anewer addition to the line-up is this mask, which has bond repair benefits in a (surprisingly lightweight) very moisturising formula for a nice all-rounder. It gets to work quickly and I often reach for it instead of conditioner. The Acidic Perfecting Concentrate Leave-In is also one of my favourite products to apply before drying my hair with a hot brush.

5. L'Oreal Professionnel Absolut Repair Molecular Shampoo

One of L’Oréal Professionnel’s latest innovations, the aptly named Absolut Repair Molecular also works at a molecular level with amino acids and peptide bonder to improve strength and elasticity. There's an in-salon treatment that's more concentrated, then three at-home products—a rinse-off serum, leave-in mask (a favourite of Marie Claire's Executive Beauty Editor, Shannon Lawlor), and this shampoo.

This has a rich formula that, of course, doesn’t feel like it strips the hair. But while it's not a leave-on treatment, I do notice a difference in how my hair feels even when I don't use it alongside the other products from the range. The scent is also lovely, a bit like it's been infused with one of the best woody perfumes.