When I first searched Olaplex vs K18, I was desperate for answers just like you.
As someone with fine, easily damaged hair, I’ve spent years babying my strands with every “bond-building” product on the market. But lately, everyone’s been raving about K18 as the next big thing.
So I did what any beauty editor would do: I tested both Olaplex and K18 on my own hair, and documented the entire experience.
Here’s everything I learned (and what you need to know before spending your money).
Products I Tested: Olaplex vs K18 (My Personal Experiment)
To get an honest comparison, I used a complete regimen from both brands over several weeks. Here’s what I used:
- READ NEXT: Olaplex Vs Ouai – I choose the winner
Olaplex Routine:
- Olaplex No.3 Hair Perfector (pre-wash treatment)
- Olaplex No.4 Bond Maintenance Shampoo
- Olaplex No.5 Bond Maintenance Conditioner
- Olaplex No.7 Bonding Oil (on damp and dry hair)
K18 Routine:
- K18 Leave-In Molecular Repair Hair Mask
- (Washed with a gentle clarifying shampoo beforehand as recommended, used Ouai Detox Shampoo)
- No conditioner or mask after shampoo (per K18 instructions)
- No other styling products, so I could test K18 on its own
Olaplex Vs K18 Comparison In Deeper Detail
Week 1-2: My Experience Using Olaplex on Fine Hair
I’ve used Olaplex for years, but this time I committed to the full regimen consistently, twice a week. No.3 before shampoo, followed by No.4 and No.5, then No.7 to seal everything in.
What I Noticed:
- My hair looked shinier by the second wash
- Breakage around my part line reduced significantly
- Felt stronger, but also a little heavy if I used too much No.5 or No.7
My thoughts: “Olaplex is the one I trust when my hair feels damaged after bleaching or heat styling. It’s the real MVP for deep repair but a bit high-maintenance as it requires more products.”
Shop The Olaplex Product I Highly Recommend
How To Use Olaplex (3) Hair Product
- Apply to damp hair from roots to ends (before shampooing).
- Leave it on for at least 10 minutes – longer if your hair is very damaged.
- Rinse thoroughly, then follow with shampoo and conditioner.
- Use once a week, or 2–3 times weekly if your hair is severely damaged.
Week 6-7: My Experience Using K18 on Fine Hair
Then after a month, I tried K18 on my colour treated hair. I’ll be honest: I was skeptical at first. No conditioner? No mask? Just one leave-in product?
But after using K18 twice a week (as directed) for two weeks, I was shocked.
What I Noticed:
- Zero frizz after my first blow-dry
- My ends looked less frayed, especially after heat styling
- Hair felt silky, lightweight, and soft, but not slippery or oily
- After 4 uses, my hair genuinely looked healthier, bouncier, and more elastic
My thoughts: “K18 gave me that ‘salon blowout’ feeling after just one use and it stayed soft even after day two. For my fine hair, this was a game-changer.”
Shop The K18 Product I Highly Recommend:
How To Use K18 Hair Product:
- Shampoo your hair (skip conditioner).
- Towel dry thoroughly to remove excess water.
- Start with 1 pump of K18 Mask. Add more if needed based on hair length, thickness, or damage.
- Work it through your hair, one pump at a time, from ends to roots.
- Wait 4 minutes to let the formula activate.
- Do not rinse out. Style your hair as usual.
K18 vs Olaplex For Breakage (find out the winner below)
Olaplex vs K18: Key Differences You Should Know
Science & Technology
- Olaplex works by rebuilding disulfide bonds in the hair shaft, especially useful after bleach, heat, and chemical treatments.
- K18 uses peptide technology that travels deeper into the cortex of the hair to reconnect broken keratin chains (the stuff hair is made of).
Both brands are backed by real science, but K18’s claims suggest fewer steps and deeper repair.
Comparison Table: Olaplex vs K18
| Feature | Olaplex | K18 |
|---|---|---|
| How it works | Repairs broken disulfide bonds | Rebuilds keratin chains at the molecular level |
| Steps involved | Multi-step system | One product, leave-in only |
| Best for | Bleached/damaged hair needing consistent TLC | All hair types, especially dry, frizzy, or fragile hair |
| Scent & Texture | Mild scent, thicker creams | Light scent, lotion-like leave-in |
What A TikTok Beauty Expert Says: Olaplex vs K18
Olaplex vs K18: Pros and Cons
Olaplex Pros
- Widely available and tested
- Great for regular damage maintenance
- Scalable system for different hair needs
Olaplex Cons
- Multi-step routine
- Can feel heavy on fine hair
- Requires consistency to see results
- Can cause breakage
K18 Pros
- Only one product needed
- Results are noticeable within 1–2 uses
- Lightweight and ideal for fine hair
- Helps with elasticity and frizz
K18 Cons
- A tiny bit expensive than Olaplex no 3
- Not a conditioner replacement (may still need hydration masks)
- Less effective if hair isn’t clarified first
The Key Differences Between K18 & Olaplex – on black hair
READ NEXT: Olaplex Clarifying Shampoo vs Ouai Detox Shampoo
FAQs: Olaplex vs K18
Is K18 better than Olaplex for damaged hair?
If you’re looking for faster results with fewer steps, K18 wins. But Olaplex may work better for long-term bond repair and deep damage after bleach.
Can you use K18 and Olaplex together?
Yes, but not at the same time. Use K18 after a separate wash, and skip conditioner. Don’t apply K18 on top of Olaplex No.3 – it’ll block absorption.
Is K18 safe for color-treated or bleached hair?
Yes! It’s specifically designed for chemically processed hair. Just make sure to clarify first for best results.
Which is better for fine hair?
K18. It delivers strength without heaviness. Olaplex can sometimes weigh fine strands down if you overdo it.
Final Thoughts: Should You Switch to K18?
After testing both, here’s what I’ve decided:
- I still love Olaplex for post-bleach days, or when I want a deep bond-building treatment.
- But when I want a quick fix, glassy ends, and lightweight volume? I’m reaching for K18 every time.
If your hair is tired, frizzy, or just not behaving lately, K18 feels like magic in a bottle.
But if you’re already mid-way through your Olaplex journey, don’t ditch it, just alternate depending on your hair’s needs.
Written by Annabelle Williams, Hair & Beauty Editor at Surge of Style
Email our team: marketing@surgeofstyle.com
This article contains affiliate links. If you purchase through my links, I may earn a commission at no extra cost to you. Prices correct at time of publication.
