K18 Leave-In Molecular Repair Hair Mask

K18's bestselling hero product and the one that made the brand famous. Applied to towel-dried hair after shampooing (skip the conditioner beforehand — it blocks the peptide), left for four minutes, then styled as normal without rinsing. The K18PEPTIDE™ reconnects broken keratin chains and disulfide bonds at the molecular level, reversing damage from bleach, colour, chemical services, and heat. Contains small amounts of drying alcohols — necessary to open the cuticle and allow the peptide to penetrate — which makes it technically CGM-modified, though it is silicone and sulphate-free. Most curly users with damaged or colour-treated hair report significantly improved elasticity, reduced breakage, and better curl definition after two to three uses. Available in a 15ml mini and 50ml full size.

Who is this for?

Our assessment — not the brand's claim

Free From

How to Use

After shampooing, towel-dry hair thoroughly — do not condition first, as conditioner blocks the peptide. Apply 1–3 pumps starting at the ends and working towards the roots. Leave for 4 minutes without rinsing. Style as normal. Use weekly or as needed — the more damaged the hair, the more dramatic the results after 2–3 uses.