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.

This 15ml mini size features a lightweight cream formula suitable for all hair types, with no extra rinse required.

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
• needs improved strength and elasticity
• feels damaged and needs greater softness and smoothness
• would benefit from a lightweight leave-in repair treatment

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

What problem does it solve?

Bleaching, colouring, chemical services and heat can cause damage to 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.

This helps renew core strength and elasticity for stronger, smoother and bouncier hair. K18 states that the treatment provides immediate and lasting results, with hair repaired from the first use and ongoing reparative benefits with continued use.

Key ingredient

K18PEPTIDE™: A biotech-developed peptide that mimics the structure of hair. It is designed to reverse damage by reconnecting polypeptide chains and disulfide bonds broken during bleaching, colouring, 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 15ml

Shampoo your hair but do not condition, then towel-dry thoroughly. Apply 3–9 pumps of K18 Leave-In Molecular Repair Hair Mask depending on your hair length and density, starting at the ends and working upwards towards the roots.

Leave the mask to sit for 4 minutes and do not rinse. Once the 4 minutes have passed, comb through, 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: 15ml
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

Less is more when using K18 Leave-In Molecular Repair Hair Mask. Apply it to clean, damp hair after shampooing and make sure you wait the full 4 minutes before combing or adding your styling products. Skip conditioner before applying the mask, as K18 states that conditioner can leave a film that prevents K18PEPTIDE™ from penetrating effectively.

Is K18 Leave-In Molecular Repair Hair Mask 15ml right for me?

Choose this if: your hair has damage caused by bleaching, colouring, chemical services or heat and you want a lightweight, 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 primary concern or you are specifically looking for a traditional rinse-out treatment rather than a leave-in molecular repair mask.

Frequently asked questions

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

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

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

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

How long should I leave K18 Hair Mask in my hair?

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

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

No. K18 is a leave-in treatment. Allow it to sit for 4 minutes and do not rinse it out.

Should I use conditioner before K18 Hair Mask?

No. K18 recommends shampooing without conditioning before applying the mask. According to K18, conditioner can leave a film that prevents the peptide from penetrating effectively.

How much K18 Leave-In Molecular Repair Hair Mask 15ml should I use?

K18's instructions for the 15ml mask recommend applying 3–9 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 treatment 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 the full 4 minutes after applying the mask, then comb through your hair and add your usual styling products.