K18 vs Olaplex vs Kérastase: What’s Actually Best for Damaged Hair? - Shelley and Co

K18 vs Olaplex vs Kérastase: What’s Actually Best for Damaged Hair?

K18 vs Olaplex vs Kérastase: What’s Actually Best for Damaged Hair?

If your hair feels dry, damaged, brittle or overprocessed, chances are you’ve heard about:

  • K18

  • Olaplex

  • Kérastase

But which one is actually best?

At Shelley & Co, this is one of the most common questions we get asked in salon — especially from blondes, extension clients and anyone trying to repair damaged hair.

The truth is, these products all work differently.

The best option depends on:

  • your level of damage

  • your hair type

  • whether your hair is coloured or bleached

  • whether you wear extensions

  • and what result you actually want

Here’s our honest salon breakdown of K18 vs Olaplex vs Kérastase — and who each range is best suited for.

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What Causes Hair Damage?

Before choosing repair products, it helps to understand what’s actually damaging the hair.

The most common causes include:

  • bleaching

  • excessive heat styling

  • colouring

  • hard water

  • sun exposure

  • extensions

  • chemical treatments

  • over-washing

  • poor quality products

Hair damage often shows up as:

  • dryness

  • breakage

  • frizz

  • split ends

  • dullness

  • tangling

  • lack of elasticity

Different products target different parts of the problem.

What Is K18 Best For?

Best for:

  • severe bleach damage

  • brittle hair

  • overprocessed hair

  • chemically damaged hair

  • internal repair

What makes K18 different?

K18 focuses on repairing damage inside the hair structure.

Unlike traditional masks that mainly coat the hair, K18 is designed to reconnect broken keratin chains caused by bleaching and chemical damage.

This makes it especially popular for:

  • platinum blondes

  • heavily highlighted hair

  • compromised hair

  • hair snapping or breaking

Clients often notice:

  • stronger hair

  • improved elasticity

  • softer ends

  • less breakage

K18 is best if:

Your hair feels stretchy, fragile, gummy or severely compromised after colouring.

👉 Shop K18 here:
Shop K18 Hair Repair Products

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What Is Olaplex Best For?

Best for:

  • ongoing maintenance

  • coloured hair

  • preventing future damage

  • strengthening weakened hair

Olaplex became famous for bond-building technology — helping reduce damage during and after colouring services.

It’s particularly good for:

  • maintaining healthier blonde hair

  • reducing breakage over time

  • supporting colour-treated hair

  • strengthening weakened strands

Olaplex is best if:

Your hair is damaged but still relatively healthy overall and you want consistent strengthening maintenance.

Many clients use Olaplex as part of their regular weekly routine rather than as an intensive rescue treatment.

👉 Shop Olaplex here:
Shop Olaplex Haircare

What Is Kérastase Best For?

Best for:

  • luxury hydration

  • softness

  • shine

  • manageability

  • dry or frizzy hair

Kérastase focuses heavily on hair feel, softness and overall hair health.

While some Kérastase ranges target repair, the brand is especially loved for creating hair that feels:

  • silky

  • smooth

  • glossy

  • expensive

At Shelley & Co, we often recommend:

  • Kérastase Première for damaged hair

  • Kérastase Gloss Absolu for shine and smoothness

  • Kérastase Blond Absolu for blonde maintenance

Kérastase is perfect for clients wanting hair that not only feels healthier — but also looks polished and luxurious.

👉 Shop Kérastase here:
Shop Kérastase Haircare

Which Is Best for Blonde Hair?

Blonde hair usually needs:

  • repair

  • hydration

  • heat protection

  • softness

Our salon opinion:

The best results often come from combining repair with hydration.

For example:

  • K18 for rebuilding damage

  • Kérastase for softness and shine

Blondes often struggle when using only strengthening products without enough moisture.

Our blonde hair favourites:

Which Is Best for Hair Extensions?

Hair extensions need:

  • lightweight hydration

  • softness

  • minimal buildup

Heavy repair products can sometimes make extensions feel coated or heavy.

For extension clients, we usually recommend balancing repair with moisture and using extension-safe products alongside treatments.

Some of our extension favourites include:

Seamless1 Leave In Cream

👉 Shop here:
Shop Seamless1 Leave In Cream

and:

Great Lengths Medium Oval Brush

👉 Shop here:
Shop Great Lengths Medium Oval Brush


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Which Is Best for Fine Hair?

Fine hair can become easily weighed down.

Usually:

  • K18 works well for targeted repair

  • lightweight Kérastase products help maintain softness

  • heavy masks should be used carefully

Fine hair generally benefits from:

  • lightweight hydration

  • less buildup

  • heat protection

  • minimal over-conditioning

👉 Shop lightweight haircare:
Shop Lightweight Haircare Products

Which Is Best for Severely Damaged Hair?

If your hair feels:

  • stretchy

  • gummy

  • snapping

  • extremely fragile

K18 is often the strongest starting point.

But long-term healthy hair usually requires:

  • repair

  • moisture

  • protection

  • reduced heat exposure

  • professional maintenance

No single product fixes everything instantly.

👉 Shop repair products:
Shop Hair Repair Treatments

Can You Use K18, Olaplex and Kérastase Together?

Yes — and honestly, many salon routines combine them.

For example:

  • K18 for intensive repair

  • Kérastase for daily softness and hydration

  • Olaplex for ongoing strengthening maintenance

The key is choosing the right balance for your hair type and damage level.

Our Honest Salon Recommendation

At Shelley & Co, we don’t believe there’s one “best” product for everyone.

The right choice depends on:

  • your hair goals

  • your colour history

  • your styling habits

  • your level of damage

  • whether you wear extensions

But generally:

  • K18 = strongest repair focus

  • Olaplex = maintenance strengthening

  • Kérastase = luxury softness, hydration and shine

The best results usually come from a customised routine rather than relying on one hero product alone.

Build Your Perfect Hair Repair Routine

Healthy hair isn’t just about using expensive products — it’s about using the right products for your hair.

Whether your goal is:

  • repairing bleach damage

  • maintaining blonde hair

  • improving softness

  • reducing breakage

  • protecting extensions

the right salon-quality routine can completely transform your hair over time.

✨ Shop professional haircare online at:
Shelley & Co Online Store

Or visit us in salon for personalised haircare recommendations tailored to your hair goals.

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