Name: Iron And Ivy Hair Studio
Price range: $$

If you’ve been in any conversation about hair health in the last few years, you’ve heard the names Olaplex and K18. Both are celebrated, both are used by professional salons worldwide, and both promise to repair and protect damaged hair. But they work through completely different mechanisms — and understanding the difference will help you choose the right one for your hair.

How Olaplex Works

Olaplex works by rebuilding disulfide bonds in the hair — the internal structural bonds that give hair its strength and integrity. During chemical processing (bleaching, colouring, perming), these bonds are broken. Olaplex contains a patented active ingredient (bis-aminopropyl diglycol dimaleate) that locates broken bonds and links them back together, rebuilding the hair’s structure from the inside out.

Olaplex is available as an in-salon treatment (used during colour services or as a standalone) and as a home-use product (the No.3 Hair Perfector). It’s cumulative — the more you use it, the more bonds are repaired and the stronger your hair becomes over time.

How K18 Works

K18 uses a different approach: it targets keratin chains — the protein structure of the hair — rather than disulfide bonds. The active ingredient (a polypeptide biomimetic) physically reconnects broken keratin chains, restoring the hair’s elasticity, strength, and softness. K18 works very quickly (4 minutes) and doesn’t require rinsing after application.

K18 is particularly effective for hair that’s lost elasticity — hair that snaps rather than stretches, or hair that feels straw-like and rough.

Which Should You Choose?

Choose Olaplex if you’re regularly bleaching or colouring your hair and want ongoing bond maintenance as part of your colour service. The cumulative effect makes it excellent for preventive care.

Choose K18 if your hair is noticeably damaged — lacking elasticity, feeling rough, or prone to breakage — and you want a fast, dramatic improvement in feel and manageability.

Use both — they don’t conflict and complement each other well. Many of our Iron + Ivy clients use Olaplex No.3 at home weekly and receive K18 as an in-salon add-on when needed.