If you've been on a hair care journey, chances are you've come across two names that dominate the conversation around damaged hair repair: K18 and Olaplex. Both promise to transform brittle, over-processed, or chemically damaged hair — but they work in very different ways. So which one is actually better for your hair?

Let's break it down.

How They Work: The Science

Olaplex

Olaplex was a game-changer when it launched, introducing a patented active ingredient called bis-aminopropyl diglycol dimaleate. This molecule works by seeking out and relinking broken disulfide bonds in the hair — the bonds that are damaged by bleach, colour, heat, and chemical treatments. Olaplex essentially repairs the hair's internal structure from the inside out.

K18

K18 takes a different approach. Its hero ingredient is a patented biomimetic peptide — a small chain of amino acids that mirrors the natural structure of keratin in your hair. Rather than relinking disulfide bonds, K18 reconnects broken polypeptide chains, which are the building blocks of the hair's cortex. The result? Hair that behaves more like it did before damage occurred.

Key Differences at a Glance

The Olaplex Range: A System Approach

One of Olaplex's biggest strengths is its comprehensive product system. From the in-salon No.0 and No.1 treatments to the at-home No.3 Hair Perfector, shampoo, conditioner, and styling products, Olaplex offers a full routine designed to work together. This makes it ideal for those who want a structured, step-by-step repair regimen.

It's particularly effective when used during colour or bleach services, as it actively protects the hair while chemical processes are taking place.

K18: Speed and Simplicity

K18's appeal lies in its simplicity and speed. The K18 Leave-In Molecular Repair Mask works in just four minutes and doesn't require rinsing. It's designed to be used after shampooing, before any other styling products, and it works on all hair types — colour-treated, heat-damaged, or naturally fragile.

Because K18 targets polypeptide chains rather than just disulfide bonds, it can address a broader spectrum of damage — including the kind caused by repeated heat styling, which Olaplex doesn't specifically target.

Which One Should You Choose?

Choose Olaplex if:

• You regularly colour, bleach, or chemically treat your hair
• You want a full at-home repair system
• You're looking for a salon-compatible treatment to use during colour services
• You prefer a rinse-out treatment as part of your wash routine

Choose K18 if:

• You want fast, fuss-free repair in four minutes
• Your damage is from heat styling as well as chemical treatments
• You prefer a leave-in formula that doesn't add extra steps
• You want visible results from the very first use

Can You Use Both?

Absolutely — and many hair professionals recommend it. Olaplex and K18 target different types of bonds within the hair, so they can complement each other rather than compete. A common approach is to use Olaplex during colour services and the K18 Molecular Repair Mask as a post-wash leave-in treatment for ongoing maintenance.

The Verdict

There's no single winner here — it really depends on your hair's needs and your lifestyle. Olaplex is the gold standard for colour-treated hair and offers a complete system for those who want a structured routine. K18 is the go-to for quick, effective repair that works across a wider range of damage types.

The good news? Both are available at Bohairmia, so you can find the right solution — or the perfect combination — for your hair.

Not sure which is right for you? Browse our full range of professional hair treatments or get in touch with our team for personalised advice.