Leave-In Molecular Repair Hair Mask

The Leave-In Molecular Repair Hair Mask by K18 is a no-rinse treatment that works at the molecular level to reverse hair damage in just 4 minutes, restoring strength, softness, shine and bounce to even the most compromised hair.

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A leave-in molecular repair treatment powered by patented K18PEPTIDE™

The product that put K18 on the map, and redefined what hair repair could actually mean.

Born from over a decade of bioengineering research, this leave-in mask goes far beyond surface conditioning, working deep within the hair fibre to reverse damage at its molecular source.

Its star active, the patented K18PEPTIDE™, is a biotech-developed biomimetic peptide engineered to slot seamlessly into hair's keratin structure and reconnect the broken polypeptide chains and disulfide bonds severed by bleaching, colour, chemical services and heat.

The result of K18 hair mask is comprehensive, lasting repair that doesn't wash away.

The lightweight cream formula applies effortlessly to damp, towel-dried hair, works its magic in just 4 minutes, then stays put as a leave-in, no rinse required. 

The hair benefits of a molecular leave-in treatment for damaged hair

• Deep molecular repair: broken polypeptide chains and disulfide bonds within the hair fibre are reconnected at the innermost level, restoring true structural strength and elasticity along the full length and width of each strand.
• Immediate and progressive results: hair feels repaired from the very first use, with benefits that build with each application and persist beyond washing.
• Addresses all damage types: bleach, colour, perms, relaxers, heat — the K18 mask targets the full spectrum of causes behind hair fibre damage.
• Stronger, smoother, bouncier hair: a rebuilt internal structure translates to visibly shinier, softer and more resilient hair, even on severely damaged strands.
• Universal formula: because K18PEPTIDE™ operates at the molecular level — where all hair is structurally identical — this mask delivers results across every hair type and texture, from fine and straight to thick and coily.

Key ingredients

• K18PEPTIDE™ – a patented biotech-developed biomimetic peptide that mirrors hair's keratin structure, reconnecting broken polypeptide chains and disulfide bonds caused by chemical, mechanical and thermal damage for comprehensive, lasting molecular repair
• Hydrolysed wheat protein – hair-identical proteins that reinforce fibre resilience, smooth the cuticle and improve softness and shine
• Hydrolysed wheat starch – a lightweight film-forming active that envelops the hair shaft, eases detangling and improves manageability without weighing hair down
• Tocopherol – vitamin E that shields the hair fibre from oxidative stress and environmental aggressors
• Citric acid – a naturally derived pH regulator that maintains the formula's optimal acidic balance, supporting cuticle closure and maximising K18PEPTIDE™ penetration

Clean leave-in molecular repair treatment suitable for all hair types and textures, particularly recommended for colour-treated, bleached, heat-damaged and chemically processed hair.

How to use the K18 Leave-In Molecular Repair Hair Mask

Shampoo hair, do not condition. Towel-dry thoroughly.

Apply 1-3 pumps depending on length and density, starting at the ends and working up toward the roots. Leave in for 4 minutes. Do not rinse out. Comb through, then style as usual with your regular products.

Use for 4-6 consecutive washes following a salon service, then as needed. Conditioner should not be applied before the mask, it can be used after the 4-minute wait if desired.