K18 Leave-In Molecular Repair Hair Mask 50ml

Repair hair damaged by bleach, color, chemical services and heat with K18 Leave-In Molecular Repair Hair Mask 50ml, a concentrated 4-minute leave-in treatment powered by patented K18PEPTIDE™ technology.

Unlike a traditional conditioning mask that primarily improves softness at the surface, K18 is designed to work within the hair's internal keratin structure. Its biomimetic peptide reconnects damaged polypeptide chains, which also helps reconnect disulfide bonds, restoring strength and elasticity through the length and width of the hair.

The result is stronger, smoother, softer and more resilient hair with improved bounce and manageability. K18 says repair begins from the first use and continues progressively, while many users see their most noticeable results after 2–3 applications.

There is no lengthy treatment time and no rinsing required. Apply after shampooing, wait just 4 minutes, then continue with your normal styling routine.

Repair → Strengthen → Restore Elasticity → Reduce Breakage → Improve Softness

Why You'll Love It

• Repairs damage caused by bleach and color
• Repairs damage from chemical services
• Helps repair heat-damaged hair
• Powered by patented K18PEPTIDE™
• Works at the molecular level within the hair
• Helps restore strength and elasticity
• Improves softness and smoothness
• Helps damaged hair feel more resilient
• Works in just 4 minutes
• No rinsing required
• Immediate and progressive repair benefits
• Lightweight, highly concentrated formula
• Suitable for all hair types
• Color-safe
• Vegan and cruelty-free

What Does K18 Leave-In Molecular Repair Hair Mask Do?

Bleaching, coloring, chemical treatments and repeated heat can damage the internal structure responsible for hair's strength and elasticity.

K18's patented K18PEPTIDE™ was developed to mimic part of hair's natural keratin structure. According to K18, the peptide fits into damaged areas and reconnects broken polypeptide chains; as a result, disulfide bonds are also reconnected.

This is why K18 is positioned differently from a conventional moisturizing hair mask.

Traditional conditioning mask → primarily conditions and softens

K18 Molecular Repair Mask → targets structural damage within the hair

It is particularly relevant when hair has become weak, brittle, rough or less elastic after bleaching, coloring, chemical processing or repeated heat styling.

Who Is It For?

Ideal for:

• Bleached hair
• Highlighted hair
• Color-treated hair
• Chemically processed hair
• Heat-damaged hair
• Fragile and brittle hair
• Hair experiencing breakage from damage
• Overprocessed hair
• Hair that has lost elasticity
• Rough, dull or damaged lengths
• Straight, wavy, curly and coily hair
• Fine, medium and coarse hair
• Anyone wanting intensive repair after a salon chemical service

Pair Me With

• K18 PEPTIDE PREP™ Detox Shampoo – deep-cleansing preparation to remove buildup and help create the optimal starting point for K18PEPTIDE™.
• K18 Molecular Repair Hair Oil – lightweight repair and finishing oil for additional smoothing, frizz control and shine after the mask's 4-minute activation period.
• K18 HeatBounce™ Conditioning Heat Protectant – protects damaged hair from heat up to 232°C / 450°F before blow-drying or hot-tool styling.
• K18 DAMAGE SHIELD Protective Conditioner – lightweight conditioning and everyday damage protection when additional softness and detangling are needed.

My Hair Feels Like Straw After Bleaching – Can K18 Help?

This is one of the strongest reasons to choose K18.

Bleaching can leave hair feeling rough, brittle, weak and less elastic because the chemical process damages the structures responsible for the hair fiber's strength.

K18 is specifically clinically tested for damage caused by bleach and color, chemical services and heat. Rather than simply coating damaged hair to make it temporarily feel smoother, K18PEPTIDE™ is designed to reconnect damaged polypeptide chains within the hair structure.

For severely overprocessed hair, results may become progressively more noticeable across several uses rather than expecting one application to completely reverse every visible sign of damage.

Does K18 Actually Repair Hair or Just Make It Feel Softer?

K18 is designed as a repair treatment rather than simply a conditioning mask.

Its K18PEPTIDE™ is a biotech-developed biomimetic peptide designed to reconnect damaged polypeptide chains within hair's keratin structure. K18 states that this also results in the reconnection of disulfide bonds, restoring strength along both the length and width of the hair fiber.

The softness, smoothness and bounce are therefore positioned as results of improved hair condition rather than simply a heavy surface coating.

How Often Should I Use K18 for Damaged Hair?

For damaged hair, K18 recommends using the mask for the first 4–6 consecutive washes, particularly following a salon service, and then using it as needed for maintenance.

K18 notes that most users see results after approximately 2–3 uses, although this varies depending on the type and severity of damage.

Importantly, more product doesn't mean more repair. The formula is highly concentrated, so correct application and dosage matter.

Full-Size Leave-In Molecular Repair Hair Mask 50mL | K18Hair

1. Shampoo, do not condition. Towel-dry thoroughly.
2. Apply 1-3 pumps of K18 leave-in molecular repair hair mask based on your length and density, starting at the ends and working up towards the roots.
3. Let sit for 4 minutes. Do not rinse out.
4. Comb, add product + style as usual. Use for 4-6 washes post-salon service, then as needed.

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.