Hair Damage/BreakageLeave-In Conditioner
Leave-In Molecular Repair Hair Mask — Reddit Reviews
by K18
Updated November 5, 2026
SH-Oligopeptide-78 strengthens brittle, processed lengths in four minutes; overuse triggers dryness.
What the community says
A leave-in peptide treatment with SH-Oligopeptide-78 and Hydrolyzed Wheat Protein, designed for chemically or heat-damaged hair. Best for brittle, bleached lengths needing strength rather than daily hydration. Overuse can leave fine hair dry, stiff, tangled, or limp.
What this means for you
What people love
- Four-minute leave-in treatment; no rinse
- Noticeably reduces breakage on bleached, heat-damaged hair
- Fine-hair HG when used sparingly
Watch out for
- Protein-overload complaints: stiff, brittle, dry hair
- Overuse can worsen tangles, frizz, or snapping
- Expensive for a tiny bottle; pump frustrates near-empty use
Product details
Use caution
Product Traits
Where to buy
Real Reddit threads — 410 mentions across 27 threads
K18 Leave-In Molecular Repair Hair Mask on Reddit, in one place — 27 threads from r/finehair, r/Haircare and 1 more, summarized.
“I'm not sure I'd spend $220 but the K18 mask was great for my hair when it was bleached.”
Positive
“stay away from k18 repair mask”
Cautionary
“K18 gives shine and sleekness and Olaplex gives fullness”
Positive
“The leave in! Pricey as hell, but I look at it more like a ’one time saloon’ treatment”
Positive
“K18 leave in mask… sorry girls but unfortunately this stuff IS worth £70.”
Positive
“Two small bottles of K18 later and you genuinely cannot even tell my hair is bleached.”
Positive
“it was noticeably more brittle and damaged”
Positive
“I like it but also makes my hair snap near the ends.”
Positive
“I've narrowed it down to the pre shampoo oil treatment, occasional clarifying shampoo, and K18 making the biggest difference in my hair.”
Positive
“K18 (Once a month)”
Positive
“K18 leave in molecular repair hair mask. You’re supposed to shampoo, rinse, towel dry your hair, put this in for 4 mins, rinse and use conditioner”
Positive
