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K18 vs Olaplex: Which Works Better?

K18 and Olaplex No.3 are two popular hair treatments for damaged hair. Both treatments repair damage to the hair shaft, but they work in different ways.

Both brands offer professional in-salon and at-home treatments to repair damaged hair, but which is better? Today, we’ll compare at-home hair repair products from both brands in this K18 vs Olaplex post.

K18 Leave-In Molecular Repair Hair Mask and Olaplex No.3 Hair Perfector

Which brand should you use? It depends on your hair condition and needs (and budget). Here’s a quick comparison of K18 and Olaplex to help you decide which treatment is right for you.

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How They Work:  Restores keratin chains (plus disulfide bonds)  Restores disulfide bonds
How They Are Used:  K18 is a post-shampoo treatment Olaplex is a pre-shampoo treatment
How Long To Work:  Minimum of 4 minutes to work  Minimum of 10 minutes to work
Price:  $75.00 for 1.7 oz  $30.00 for 3.3 oz.
K18 vs Olaplex:

K18 vs Olaplex

K18 Leave-In Molecular Repair Hair Mask and Olaplex No.3 Hair Perfector handheld.

The MAIN DIFFERENCE between K18 and Olaplex is that K18 restores keratin chains and disulfide bonds, and Olaplex restores disulfide bonds, so it can argued that K18 is a more complete treatment.

Keratin chains are a structural component of hair (think of the vertical legs/sides of a ladder), and disulfide bonds (think of the horizontal rungs of a ladder) are the chemical bonds that hold keratin chains together.

K18 Leave-In Molecular Repair Hair Mask and Olaplex No.3 Hair Perfector sampled on hand.

Differences Between K18 and Olaplex

  • ✅ Instead of providing a temporary fix and restoring one type of bond, as Olaplex does with disulfide bonds, K18 mimics the molecular makeup of keratin chains along the length and width of your hair fibers to improve strength and elasticity.
  • ✅ K18’s proprietary ingredient is K18PEPTIDE (sh-Oligopeptide-78), and Olaplex’s proprietary ingredient is Bis-Aminopropyl Diglycol Dimaleate.
  • ✅ Olaplex is a pre-shampoo treatment, and K18 is a post-shampoo treatment.
  • ✅ K18 takes a minimum of 4 minutes to work. Olaplex No.3 takes a minimum of 10 minutes to work.
  • ✅ While K18 is my pick for complete damage repair, it doesn’t come cheap. The price of K18’s best-selling hair mask is more than 2x that of Olaplex No.3 Hair Perfector treatment, and the K18 bottle size is smaller.

K18 Leave-In Molecular Repair Hair Mask

K18 Leave-In Molecular Repair Hair Mask

K18 Leave-In Molecular Repair Hair Mask is K18’s star at-home product. It is a biotech-driven leave-in hair treatment that repairs hair damage in 4 minutes.

Quite a bold claim, I know. But K18PEPTIDE works deep within your hair strand to repair damage from heat, bleaching, coloring your hair, and chemical services.

And…the more you use it, the better it works. (It doesn’t wash out.) I can attest to this. I’ve had great results with K18 improving my hair elasticity.

The full-size bottle with pump is 1.7 oz, and it also comes in a smaller 0.5 oz bottle.

How Does K18 Leave-In Molecular Repair Hair Mask Work?

K18 uses its proprietary K18PEPTIDE to restore broken keratin chains in your hair.

K18 uses an easy-to-understand analogy to describe how K18 works:

Think of skincare vs makeup. While concealer (most hair care products) may cover up an imperfection, K18 works like retinol.

Retinol works at a deeper layer to improve your skin, so you will need less concealer in the future.

The mask contains added fragrance that is described as a light floral scent with notes of jasmine and peony. Results can typically be seen after 2-3 uses.

K18 Hair Mask does not contain parabens, sulfates, silicones, phthalates, sodium chloride, artificial colors, formaldehyde, or formaldehyde donors.

K18 is vegan, cruelty-free, and color-safe.

How To Use K18 Leave-In Molecular Repair Hair Mask

Shampoo your hair, and do not use a conditioner.* Apply K18 Leave-In Molecular Repair Hair Mask to towel-dried hair. Start with 1 pump and apply it evenly from root to ends.

You can use more than 1 pump depending on your hair length and condition, but most people will need only about a dime-size or two dime-size amounts since the treatment is highly concentrated.

Curly, coily, and thick hair might need up to 3 pumps, whereas the average amount required is 2 pumps. Avoid using more than 3 pumps.

Wait for 4 minutes until you comb or style your hair. You can apply styling products after using K18 mask, but don’t use them before you apply the hair mask.

Use K18 for 4-6 consecutive hair washes, and then use it as needed to maintain your smoother, softer, healthier hair. (If you wash your hair daily, you can use K18 every day for 4-6 days.)

*Because conditioner or other hair products will form a film on your cuticle, it will block K18 from being absorbed into the inner layers of your hair.

You can apply a leave-in conditioner after the 4-minute waiting period if you want extra conditioning.

Olaplex No.3 Hair Perfector

Olaplex No.3 Hair Perfector

Olaplex No.3 Hair Perfector is a WEEKLY at-home hair repair treatment that strengthens hair while reducing breakage. It’s very popular as it’s the #1 product in prestige haircare.

The pH-balanced treatment works to rebuild and relink the broken disulfide bonds during thermal, mechanical, and chemical hair processes for stronger, healthier hair.

You can use No.3 on its own or pair it with No.0 Intensive Bond Building Hair Treatment, which contains the highest concentration of Olaplex’s patented bond-building technology of all of Olaplex’s at-home products.

No.0 primes the hair for repair and must be used with No.3, as it boosts No.3’s benefits. The duo forms a two-part system for better results.

Per Olaplex, they provide 68% more repair & 3x stronger hair in just one use.

This Olaplex hair treatment is vegan and cruelty-free. It’s also free of DEA, aldehydes, formaldehyde, gluten, nuts, parabens, phthalates, phosphate, and sulfate.

How Does Olaplex No.3 Work?

Olaplex No.3 works by rebuilding broken disulfide bonds in the hair. Disulfide bonds give our hair its structure and strength.

The patented ingredient in Olaplex, Bis-Aminopropyl Diglycol Dimaleate, seeks out and reconnects these broken bonds.

When used as directed, Olaplex No.3 can help to repair damaged hair, making it stronger and healthier.

It can also be used as a preventative measure to help protect hair from damage caused by heat styling, chemical treatments, and exposure to the sun and pollution.

How To Use Olaplex No.3 Hair Perfector

Apply Olaplex No.3 Hair Perfector to damp, towel-dried hair and comb through from roots to ends.

You don’t have to wash your hair before using No.3, but it’s probably a good idea to wash your hair before using No.3 if you have a lot of product in your hair.

Leave No.3 on your hair for a minimum of 10 minutes. Olaplex notes that maximum effectiveness is achieved at 30-45 minutes.

Once you’re ready, rinse, shampoo, and condition your hair as usual. With each use, you’ll notice that your hair is softer, shinier, and healthier-looking.

Use Olaplex Nº.3 once a week or two to three times a week for damaged hair.

Can You Use K18 and Olaplex Together?

K18 Leave-In Molecular Repair Hair Mask and Olaplex No.3 Hair Perfector

Good news! Since K18 and Olaplex work on the structure of your hair in different ways, you can use them together for even better results.

Use Olaplex N0.3 Hair Perfector before you shampoo and use K18 Leave-In Molecular Repair Hair Mask after you shampoo (skip the conditioner).

You can also mix and match products. You can use K18 Hair Mask and follow with Olaplex styling products for a bond-building boost after you work on repairing keratin chains.

If you like Olaplex shampoos like I do, you can use one with K18 Hair Mask. Or use K18 shampoos with Olaplex treatments and conditioners.

K18 Peptide Prep pH Maintenance Shampoo vs Olaplex Bond Maintenance Shampoo

  • ✅ The main difference between these two shampoos is that K18 contains K18PEPTIDE and Olaplex contains Bis-Aminopropyl Diglycol Dimaleate to treat damaged hair.
  • ✅ Olaplex has a thicker and more concentrated consistency.
  • ✅ K18 is more expensive than Olaplex.
K18 Peptide Prep pH Maintenance Shampoo and Olaplex No.4 Bond Maintenance Shampoo.

K18 Peptide Prep pH Maintenance Shampoo

K18 Peptide Prep pH Maintenance Shampoo is a color-safe shampoo that is pH-optimized to support the hair cuticle and prevents excess water from entering the hair, which can create frizz, tangles, and dullness.

This shampoo, formulated with K18PEPTIDE, prevents the hair cuticle from swelling during washing, protecting your hair color and moisture levels.

The formula removes dirt and oil without disrupting the hair or scalp microbiome. It has a light floral scent.

Olaplex Bond Maintenance Shampoo

Olaplex Bond Maintenance Shampoo is a reparative shampoo that protects hair from frizz, split ends, and other damage.

It relinks broken bonds and helps reduce breakage. It contains Bis-Aminopropyl Diglycol Dimaleate, Olaplex’s patented ingredient that reconnects broken disulfide bonds.

The color-safe shampoo is very concentrated, so a little bit goes a long way. It has the same bright, citrusy Olaplex scent as the rest of the Olaplex product line.

Formulated at a pH of 6-6.5, the shampoo leaves your hair softer, shinier, and more manageable. This is one of my favorite shampoos, leaving my hair so soft and silky.

K18 Peptide Prep Detox Shampoo vs Olaplex Nº.4C Bond Maintenance Clarifying Shampoo

  • ✅ Both detox shampoos target product buildup, oil, sebum (oil), and metal found in tap and hard water.
  • ✅ K18 contains K18PEPTIDE to repair broken keratin chains, activated charcoal, and salicylic acid to clear away buildup, while Olaplex contains Bis-Aminopropyl Diglycol Dimaleate to repair broken disulfide bonds in your hair.
  • ✅ Both detox shampoos have a light, refreshing scent and are color-safe.
  • ✅ K18 is more expensive than Olaplex.

K18 Peptide Prep Detox Shampoo

K18 Peptide Prep Detox Shampoo is a clarifying shampoo that removes 99% product buildup, 95% sebum, and 76% copper without stripping your hair.

It contains activated charcoal to remove oil and other buildup and salicylic acid to help unclog pores in the scalp.

The color-safe shampoo removes buildup that can damage hair, weigh hair down, and leave hair dull and frizzy with a rough, dry texture.

The shampoo unclogs hair follicles, sweeping away dirt, oil, silicone, and other buildup, and removes metals commonly found in tap and hard water.

The pH-optimized formula contains K18PEPTIDE and preps hair for K18 Molecular Repair Leave-in Treatment. It has a pH of 3.8-4.2 to maintain hair color without dryness.

K18 Peptide Prep Detox Shampoo pairs really well with K18 Hair Mask because it removes product or other pollutants that prevent the mask and its biomimetic peptide from penetrating your hair.

So, if you don’t see the results you want from K18, this shampoo might improve your results (it did for me!).

The shampoo has a dark gray shade and K18’s light floral scent.

Olaplex No.4C Bond Maintenance Clarifying Shampoo

Olaplex No. 4C Bond Maintenance Clarifying Shampoo, handheld.

Olaplex No.4C Bond Maintenance Clarifying Shampoo removes impurities in a sulfate-free & pH-balanced formula. It contains Bis-Aminopropyl Diglycol Dimaleate to repair broken bonds in your hair.

This once-weekly shampoo gets rid of excess oil, product buildup, chlorine, hard water minerals, heavy minerals, and other pollutants without drying out your hair.

The shampoo uses Olaplex’s patented Bond Building Technology and a Broad Spectrum Clarifying System to clean your scalp, restore shine, and leave your hair with volume, softness, and vibrant color clarity.

The shampoo contains Olaplex’s signature citrus scent.

K18 Hair Oil vs Olaplex Oil

K18 Molecular Repair Hair Oil and Olaplex No. 7 Bonding Oil.
  • ✅ Both oils are lightweight and don’t leave your hair greasy or feeling heavy.
  • ✅ K18 contains K18PEPTIDE to repair broken keratin chains, including disulfide bonds; Olaplex contains Bis-Aminopropyl Diglycol Dimaleate to repair broken disulfide bonds in your hair.
  • ✅ Both oils maintain color vibrancy and are color-safe up to 450°F (232°C).
  • ✅ K18 is more than twice the price of Olaplex.

K18 Molecular Repair Hair Oil

K18 Molecular Repair Hair Oil, handheld.

K18 Molecular Repair Hair Oil is a nourishing hair oil designed to transform damaged and brittle hair.

The concentrated oil contains avocado oil, sunflower oil, hemi-squalane, squalane, and K18’s proprietary biomimetic peptide to help repair and restore damaged hair.

Benefits include:

  • Reverses Hair Damage: Works at two levels of the hair fiber to repair damaged hair with K18’s patented biomimetic peptide.
  • Reduces Frizz/Flyaways: The natural oils in the formula smooth your hair cuticles and soften your tresses.
  • Boosts Shine: Provides nourishment and hydration, leaving your hair shiny and vibrant.
  • Color Vibrancy:  Helps to maintain color clarity and reduce fading.
  • Heat Protection: Protects against heat styling damage by creating a barrier between the hot tools and your hair. Protects up to 450°F (232°C).

Olaplex No. 7 Bonding Oil

Olaplex No. 7 Bonding Oil

Enriched with a unique blend of moringa seed oil, sunflower seed oil, and Olaplex’s patented bond-building technology, Olaplex No. 7 Bonding Oil is formulated to rejuvenate and fortify damaged hair with its lightweight formula.

Benefits include:

  • Olaplex Bond Building: Formulated with OLAPLEX’s patented technology, this oil is specifically designed to strengthen and protect hair, ensuring visibly healthier-looking locks.
  • Boosts Hair Health: The oil significantly boosts shine and softness, leaving your hair not only repaired but also brighter and more vibrant.
  • Heat Defense: Offers protection against heat styling, withstanding temperatures up to 450º F (232º C).
  • Color-Safe: Helps to maintain hair color and prevent fading, making it a must-have for color-treated hair.

About K18

Although K18 was launched in 2020, K18 scientists spent the prior decade testing decapeptide sequences in the human keratin genome.

They found a unique sequence with the correct size and molecular structure that would reconnect broken polypeptide chains and bring back over 90% of hair strength and elasticity.

The result of their research is K18PEPTIDE (sh-Oligopeptide-78), K18’s patented peptide that reverses hair damage from bleach and color, chemical services, and heat in just 4 minutes.

A peptide is a short chain of amino acids that occurs naturally in the body. Peptides are the building blocks of protein, and they play an important role in many biological processes.

K18PEPTIDE is a biomimetic peptide, which means it mimics the structure of keratin proteins and reconnects broken keratin chains.

K18 Reset + Repair Hair Kit box with K18 Peptide Prep Detox Shampoo and K18 Leave-In Molecular Repair Hair Mask, overhead shot" "hair like new in 4 minutes."

K18 targets the broken polypeptide chains (keratin chains), which are deep in the core of the hair strand. In fact, there are billions of polypeptide chains in each hair strand.

While traditional bond repair products only reach the cortex of the hair strand and wash out over time, K18 reaches the molecular level and reconnects broken chains.

It also re-conforms broken disulfide bonds, which is what Olaplex is known for.

K18 works on the y-axis (length) and the x-axis (width) of your hair strands. It restores hair strength and elasticity for softer, smoother, shiner, and healthier hair.

Besides K18’s star at-home product, K18 Leave-In Molecular Repair Hair Mask, the brand also offers two shampoos, Peptide Prep pH Maintenance Shampoo and Peptide Prep Detox Shampoo, along with in-salon treatments.

K18 products are formulated for all hair types.

Related Post: Gisou Hair Oil Dupes

About Olaplex

Olaplex Bond Building Haircare System.

Olaplex Bond Maintenance System is a multi-step at-home system that works on all hair types to restore strength, structure, and integrity to damaged hair.

Our hair contains millions of disulfide bonds, which can weaken and break due to chemical treatments, heat styling, aging, environmental stress, and everyday wear and tear.

When these bonds break, our hair becomes damaged, dry, and brittle.

Olaplex repairs all types of hair damage with its patented Bond Building Technology. This technology uses Olaplex’s proprietary ingredient, Bis-Aminopropyl Diglycol Dimaleate, to repair broken disulfide bonds between the proteins in your hair.

The technology works at a molecular level and provides immediate results. It improves hair strength and prevents future breakage for shiny, healthy hair with improved resilience.

Olaplex products are vegan, cruelty-free, and do not contain sulfates, parabens, or phthalates.

The Olaplex at-home system is comprised of several products:

  • No.0 Intensive Bond Building Hair Treatment
  • No.3 Hair Perfector
  • No.4 Bond Maintenance Shampoo
  • No.4P Blonde Enhancer Toning Shampoo
  • No.4C Bond Maintenance Clarifying Shampoo
  • No.5 Bond Maintenance Conditioner
  • No.6 Bond Smoother
  • No.7 Bonding Oil
  • No.8 Bond Intense Moisture Mask
  • No.9 Bond Protector Nourishing Hair Serum

Olaplex Steps No.1 and No.2 are in-salon services.

K18 vs Olaplex: Which Is Best For Your Hair?

Both K18 and Olaplex work to repair damaged hair, no matter your hair type.

K18 targets keratin chains, which helps rebuild the hair’s structure from the inside out, strengthening both the length and the width of the hair shaft (i.e., the sides and rungs of a ladder).

Olaplex works by reconnecting the broken disulfide bonds in the hair (i.e., the rungs of a ladder).

So, which treatment is best for your hair?

If you have damaged hair, both K18 and Olaplex can help. If you have very damaged hair, K18 may be a better option because it helps to rebuild the hair’s structure and won’t eventually wash out.

For another comparison of hair care products for damaged hair, check out this post on Pureology vs Redken.

Thanks for reading!


Friday 25th of November 2022

K18 is damn damn expensive it's catered only to the super rich not for us middle class people 😭😭


Sunday 27th of November 2022

It is expensive. I waited until the Sephora Fall Sale to buy it at a discount.