Best for: All hair types with damage caused by bleach and colour, chemical services or heat.

What is K18 Leave-In Molecular Repair Hair Mask?

K18 Leave-In Molecular Repair Hair Mask is a 4-minute leave-in treatment designed to repair hair damage at a molecular level. Powered by K18PEPTIDE™, the formula works to reconnect polypeptide chains and disulfide bonds broken during bleaching, colouring, chemical services and heat, helping to restore strength, softness, smoothness and bounce to damaged hair.

Its lightweight cream format is suitable for all hair types and provides detangling and softening benefits without requiring an additional rinse.

Who is it best for?

K18 Leave-In Molecular Repair Hair Mask may suit you if your hair:

• has been damaged by bleach or colour
• has undergone chemical services
• has been exposed to heat damage
• feels damaged and needs improved strength and elasticity
• needs greater softness, smoothness and bounce
• would benefit from a lightweight leave-in repair treatment

The formula is designed to work across all hair types.

What problem does it solve?

Bleaching, colouring, chemical services and heat can damage the structure of the hair. K18 Leave-In Molecular Repair Hair Mask is designed to work at the innermost layer of the hair, reconnecting polypeptide chains and, as a result, disulfide bonds.

K18 describes this as providing repair across the length and width of the hair, helping renew core strength and elasticity for stronger, smoother and bouncier hair.

The treatment starts working from the first use, with K18 stating that the results last beyond the next wash and become progressively reparative with continued use.

Key ingredient

K18PEPTIDE™: A biotech-developed peptide designed to mimic the structure of hair. It works by reconnecting polypeptide chains and disulfide bonds that have been broken by bleaching, colour, chemical services and heat.

The formula is also pH-optimised at 5.0–6.0 to help minimise cuticle swelling and put hair proteins in their most resilient state.

Ingredients

Water (Aqua) (Eau), Alcohol Denat., Propylene Glycol, Cetearyl Alcohol, Dicaprylyl Ether, Cetyl Esters, Behentrimonium Chloride, Polysorbate 20, sh-Oligopeptide-78, Hydrolyzed Wheat Protein, Hydrolyzed Wheat Starch, Isopropyl Alcohol, Tocopherol, Phenoxyethanol, Potassium Sorbate, Citric Acid, Fragrance (Parfum), Geraniol, Linalool, Hexyl Cinnamal, Benzyl Alcohol, Amyl Salicylate, Benzaldehyde.

How to use K18 Leave-In Molecular Repair Hair Mask

Shampoo your hair but do not condition. Towel-dry thoroughly, then apply 1–3 pumps of K18 Leave-In Molecular Repair Hair Mask depending on your hair length and density, beginning at the ends and working upwards towards the roots.

Leave for 4 minutes and do not rinse. Once the 4 minutes have passed, comb through your hair, add your usual styling products and style as normal.

Use for 4–6 washes following a salon service, then use as needed.

Why choose it?

Hair type: All hair types
Primary concern: Hair damage
Best for: Damage caused by bleach, colour, chemical services and heat
Texture: Lightweight cream
Key ingredient: K18PEPTIDE™
Size: 50ml
Routine step: Treat
Treatment time: 4 minutes
Rinse out: No
pH: 5.0–6.0
Vegan: Yes
Colour-safe: Yes
Cruelty-free: Yes
Brand: K18

Millies Expert Advice

Because less is more with K18, start with the recommended amount for your hair length and density rather than applying a large amount like a traditional rinse-out hair mask. Make sure you shampoo without conditioning first, towel-dry thoroughly and allow the mask to sit for the full 4 minutes before combing or adding your styling products.

Is K18 Leave-In Molecular Repair Hair Mask right for me?

Choose this if: your hair has damage caused by bleaching, colouring, chemical services or heat and you want a 4-minute leave-in treatment designed to restore strength, softness, smoothness and bounce.

Consider another product if: repairing this type of hair damage isn't your main hair concern or you're specifically looking for a traditional rinse-out conditioning mask rather than a leave-in molecular repair treatment.

Frequently asked questions

What does K18 Leave-In Molecular Repair Hair Mask do?

K18 Leave-In Molecular Repair Hair Mask is designed to reverse hair damage at a molecular level. Its K18PEPTIDE™ reconnects polypeptide chains and disulfide bonds broken by bleaching, colour, chemical services and heat.

Is K18 Leave-In Molecular Repair Hair Mask suitable for all hair types?

Yes. K18 states that the mask is effective across all hair types because K18PEPTIDE™ works at a molecular level.

How long do you leave K18 Hair Mask in your hair?

Leave K18 Leave-In Molecular Repair Hair Mask in the hair for 4 minutes before combing or adding styling products.

Do you rinse out K18 Leave-In Molecular Repair Hair Mask?

No. K18 is a leave-in treatment and should not be rinsed out after the 4-minute treatment time.

Should I use conditioner before K18?

No. Shampoo your hair and skip conditioner before applying the K18 mask. K18 advises that conditioner can leave a film that prevents the peptide from penetrating effectively.

How much K18 Hair Mask should I use?

Apply 1–3 pumps depending on the length and density of your hair, beginning at the ends and working upwards towards the roots.

How often should I use K18 Leave-In Molecular Repair Hair Mask?

K18 recommends using the mask for 4–6 consecutive washes following a salon service and then using it as needed.

Can I use styling products after K18 Hair Mask?

Yes. Wait for the full 4 minutes after applying K18, then comb your hair and apply your usual styling products.