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OLAPLEX

No.9 Bond Protector Heat Protection & Frizz Reduction Nourishing Hair Serum

Finisher / Serum, lean

  • Finisher
  • serum
Size3 fl oz
Price$29.99seen at one store · 3 oz
Price / oz$10.00/ozat 3 oz
Where to buy1 store

Scent:

The ingredient list declares fragrance. What it smells of is not stated, and we do not guess.

Listing used for research: target.com

Personal fit

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Upper-mid price for a serum

$10.00/oz at 3 oz — more than 53% of the 79 serums , which mostly run $3.27–14.46/oz.

Price and stores

Great for

Maximum slipfor hair that tangles the moment it is wet

Maybe skip if

this product carries a scent
Anyone who dislikes a castthe film formers here can set firm
Hair that reads dullno recognised shine system in the list
Dry or very humid airwhere heavy humectants work against you
Tight budgetsit sits in the upper price tiers
Picking it up locallywe have it recorded in one channel only

Whether a finisher this rich will read as shine or as grease depends on your strand thickness and oil rate — that is what the consultation works out.

What the formula actually does

Read from the label, not the marketing

Each row says where it comes from: F means we derived it from this product’s own ingredient list, S means it is a claim the brand makes that the formula neither confirms nor contradicts.

Oils and butters None

No oils or butters in the list.

Needs detergent to remove No

Nothing here needs a detergent wash to remove.

Fragrance Present

Fragrance is listed; it sits below the working ingredients.

from the formula stated by the brand reported by reviewers Scale: 1 dot low · 5 dots high, within this product type.

Ingredients that matter

The ingredients that change a decision

The workhorse ingredients plus anything lower down that changes a decision. These chips name what an ingredient does — they are not safety scores, and no ingredient here is rated good or bad on its own.

IngredientWhat it doesWhy it mattersChip
WaterWater (aqua/eau) solvent The base everything else is dissolved in Neutral
Propanediol humectant Pulls water into the hair Moisturizes
Betaine humectant Pulls water into the hair Moisturizes
quaternium-22 Neutral
Sodium Hyaluronate humectant Pulls water into the hair Moisturizes
Bis-Aminopropyl Diglycol Dimaleate conditioning agent Reduces combing force Detangles
Cetrimonium Chloride conditioning agent Conditions and softens — this is what makes it comb through Detangles
Panthenol humectant Pulls water into the hair Detangles
Fragrancefragrance (parfum) fragrance The scent Fragrance
Citral fragrance The scent Fragrance
Citronellol fragrance The scent Fragrance
Hexyl Cinnamal fragrance The scent Fragrance
What the list leaves out, and what it carriesFragrance is on the label. Hard-water chelators are present.
Full ingredient list (30)

US labelling rules put ingredients above 1% in descending order of amount; below 1% they may be listed in any order. Annotations keep three readings separate: the ingredient's general function, its role in this product type, and what its position can support.

  • 1 Water · Water (aqua/eau)
    General function

    The base of almost every rinse-off and cream hair product. It carries everything else and is normally the first ingredient on the label.

    Leading ingredient

    Listed in the first three ingredients, it is likely a structural part of this formula.

    • solvent
  • 2 Propanediol
    General function

    A corn-derived humectant and solvent, often chosen as a lighter-feeling alternative to propylene glycol.

    Leading ingredient

    Listed in the first three ingredients, it is likely a structural part of this formula.

    May suitFine or easily flattened hair

    Light and water-binding rather than oily, so it hydrates without contributing weight.

    May suitVery dry or highly damaged hair

    A small water-binding solvent. It holds moisture and helps the rest of the formula spread evenly over the strand.

    DependsClimate-sensitive or frizz-prone hair

    A humectant follows the air: it holds water in humid conditions and can give it up in very dry ones. Climate decides what it does more than the label does.

    PubChem
    • humectant
    • solvent
  • 3 Betaine
    General function

    A sugar-beet derived humectant that binds water. Despite the name it is not a cleanser like cocamidopropyl betaine.

    Leading ingredient

    Listed in the first three ingredients, it is likely a structural part of this formula.

    May suitDry, coarse, or high-porosity hair

    High-porosity hair loses water fast; a humectant holds some of it in place for longer than the wash itself would.

    May suitVery dry or highly damaged hair

    Binds water into the outer layers of the strand, and water is what makes dry hair flexible again rather than brittle.

    DependsClimate-sensitive or frizz-prone hair

    A humectant moves water in whichever direction the air allows: it holds moisture in humid conditions and can pull it back out of hair in very dry ones.

    PubChem
    • humectant
  • 4 quaternium-22
  • 5 Sodium Hyaluronate
    General function

    A large water-binding molecule that sits on the surface holding moisture.

    Supporting ingredient

    Listed in positions 4–8, it likely makes a meaningful contribution alongside the formula's main ingredients.

    May suitDry, coarse, or high-porosity hair

    High-porosity hair loses water fast; a humectant holds some of it in place for longer than the wash itself would.

    May suitVery dry or highly damaged hair

    Binds water into the outer layers of the strand, and water is what makes dry hair flexible again rather than brittle.

    DependsClimate-sensitive or frizz-prone hair

    A humectant moves water in whichever direction the air allows: it holds moisture in humid conditions and can pull it back out of hair in very dry ones.

    • humectant
  • 6 Bis-Aminopropyl Diglycol Dimaleate
    General function

    A bond-repair ingredient that reacts with sulfur groups in the hair. It is the active in one of the widely marketed bond-building systems.

    Supporting ingredient

    Listed in positions 4–8, it likely makes a meaningful contribution alongside the formula's main ingredients.

    May suitFrizz-prone, damaged, or high-friction hair

    Deposits a lubricating layer that makes combing easier, which is most of what stops mechanical damage adding to frizz.

    • conditioning agent
  • 7 Cetrimonium Chloride
    General function

    A quick-acting conditioning agent that reduces static and combing force. It also helps keep the formula stable.

    Supporting ingredient

    Listed in positions 4–8, it likely makes a meaningful contribution alongside the formula's main ingredients.

    May suitFine or easily flattened hair

    The C16 quat binds mostly by charge rather than by chain, so it deposits measurably less than the C22 ones. Less deposit is less conditioning and also less weight, which is usually the trade fine hair wants.

    May suitFrizz-prone, damaged, or high-friction hair

    A cationic conditioning agent: it binds to the damaged, negatively charged parts of the cuticle and lowers combing friction there.

    DependsBuild-up-sensitive routines

    Substantive by design. A routine with no detergent wash gives it nothing to leave with.

    International Journal of Cosmetic Science
    • conditioning agent
    • cleanser
  • 8 Panthenol
    General function

    Provitamin B5. It draws in water and penetrates the strand a little, which is why it is the standard ingredient for softness and shine claims.

    Supporting ingredient

    Listed in positions 4–8, it likely makes a meaningful contribution alongside the formula's main ingredients.

    May suitFine or easily flattened hair

    It hydrates without adding oil or a film, which is the combination fine hair usually needs.

    May suitFrizz-prone, damaged, or high-friction hair

    Deposits a lubricating layer that makes combing easier, which is most of what stops mechanical damage adding to frizz.

    May suitVery dry or highly damaged hair

    A humectant that also penetrates the cuticle, so it holds water inside the strand rather than only on the surface.

    PubChem
    • humectant
    • conditioning agent
    • vitamin
  • 9 Hydroxyethylcellulose
    General function

    A cellulose thickener that gives gels and conditioners their body and adds a soft, flexible film.

    Secondary ingredient

    Lower in the ordered portion of the list, it is more likely playing a supporting role than defining the formula.

    May suitCurls or waves needing flexible hold

    A polysaccharide film stays softer than a synthetic one as it dries, which is what leaves a curl defined but still able to move.

    May suitFrizz-prone, damaged, or high-friction hair

    A soft film binds neighbouring strands together, which is most of what keeps flyaways lying down without stiffness.

    May not suitMaximum-hold styling

    Gum films stay soft. A style that needs firm fixation usually wants a synthetic polymer doing the holding.

    PubChem
    • gum
    • thickener
    • film former
  • 10 PVP
    General function

    A classic hairspray polymer. It gives firm hold but attracts moisture, so humidity can soften the set.

    Secondary ingredient

    Lower in the ordered portion of the list, it is more likely playing a supporting role than defining the formula.

    May suitMaximum-hold styling

    Synthetic film formers dry into a continuous film, which is what holds a shape against movement and against humid air.

    DependsBuild-up-sensitive routines

    Some acrylate copolymers rinse with water and some need a detergent; the label alone does not say which one a formula used.

    May not suitClimate-sensitive or frizz-prone hair

    The film takes up water from the air. The patent work that produced the VP/VA copolymers describes a PVP film turning sticky after time in a humid atmosphere, and being dependable only where humidity is low — so hold and feel both move with the weather.

    PubChem
    • film former
    • polymer
  • 11 Guar Hydroxypropyltrimonium Chloride
    General function

    A conditioning polymer made from guar bean gum. It deposits during rinsing, which is why sulfate shampoos can still leave hair soft.

    Secondary ingredient

    Lower in the ordered portion of the list, it is more likely playing a supporting role than defining the formula.

    May suitCurls or waves needing flexible hold

    Gums thicken and set soft, which gives definition that bends rather than a rigid cast.

    May suitFrizz-prone, damaged, or high-friction hair

    Cationic conditioners bind to the negatively charged damaged cuticle, laying it flat and cutting the friction that causes combing breakage.

    May suitMaximum-hold styling

    A styling polymer dries into a film across the strands, which is what makes a shape hold instead of relax.

    • conditioning agent
    • polymer
    • gum
  • 12 Furcellaria Lumbricalis Extract
    • botanical extract
  • 13 Pelvetia Canaliculata Extract
    • botanical extract
  • 14 Xylitylglucoside
    General function

    A sugar-derived humectant used for lasting moisture without stickiness.

    Secondary ingredient

    Lower in the ordered portion of the list, it is more likely playing a supporting role than defining the formula.

    May suitDry, coarse, or high-porosity hair

    High-porosity hair loses water fast; a humectant holds some of it in place for longer than the wash itself would.

    May suitVery dry or highly damaged hair

    Binds water into the outer layers of the strand, and water is what makes dry hair flexible again rather than brittle.

    DependsClimate-sensitive or frizz-prone hair

    A humectant moves water in whichever direction the air allows: it holds moisture in humid conditions and can pull it back out of hair in very dry ones.

    PubChem
    • humectant
  • 15 Polyquaternium-44
    General function

    A positively charged conditioning polymer. It leaves a thin film that cuts static and eases combing, and it survives rinsing better than a simple conditioner.

    Secondary ingredient

    Lower in the ordered portion of the list, it is more likely playing a supporting role than defining the formula.

    May suitCurls or waves needing flexible hold

    Cationic polymers hold a curl loosely and stay soft, which is why they turn up in definition products rather than firm-hold ones.

    May suitFrizz-prone, damaged, or high-friction hair

    A cationic polymer stays on the hair through rinsing, which is what keeps static and combing friction down after the wash.

    May suitMaximum-hold styling

    Film formers are what hold a style: they dry into a connected film across the strands so the shape resists movement.

    • conditioning agent
    • film former
    • polymer
  • 16 Anhydroxylitol
    General function

    A sugar-derived humectant used with xylitol for a light moisturised feel.

    Secondary ingredient

    Lower in the ordered portion of the list, it is more likely playing a supporting role than defining the formula.

    May suitDry, coarse, or high-porosity hair

    High-porosity hair loses water fast; a humectant holds some of it in place for longer than the wash itself would.

    May suitVery dry or highly damaged hair

    Binds water into the outer layers of the strand, and water is what makes dry hair flexible again rather than brittle.

    DependsClimate-sensitive or frizz-prone hair

    A humectant moves water in whichever direction the air allows: it holds moisture in humid conditions and can pull it back out of hair in very dry ones.

    PubChem
    • humectant
  • 17 Maltitol
    General function

    A sugar alcohol used as a humectant with a light, non-sticky feel.

    Secondary ingredient

    Lower in the ordered portion of the list, it is more likely playing a supporting role than defining the formula.

    May suitDry, coarse, or high-porosity hair

    High-porosity hair loses water fast; a humectant holds some of it in place for longer than the wash itself would.

    May suitVery dry or highly damaged hair

    Binds water into the outer layers of the strand, and water is what makes dry hair flexible again rather than brittle.

    DependsClimate-sensitive or frizz-prone hair

    A humectant moves water in whichever direction the air allows: it holds moisture in humid conditions and can pull it back out of hair in very dry ones.

    • humectant
  • Below about this point, order stops being meaningful — these are typically used at 1% or less.
  • 18 Citric Acid
    General function

    Used to bring the product to a slightly acidic pH, which helps the cuticle lie flat. It is almost always near the end of the list.

    Estimated lower-concentration zone

    It appears around or below the estimated 1% line, where label order no longer indicates relative amount; its role may be minor or technical.

    May suitBuild-up-sensitive routines

    Holds hard-water minerals in solution so they rinse away instead of depositing on the hair.

    May suitFrizz-prone, damaged, or high-friction hair

    The acid side of pH adjustment, and the reason it matters is measured: alkaline formulas raise the fibre's surface negative charge, increase friction between strands and lift the scales, while lower-pH ones do the reverse.

    May suitGray, silver, or brass-prone hair

    Where a warm cast comes from water minerals rather than from the hair itself, holding those metals in solution is what removes it.

    International Journal of Trichology
    • pH adjuster
    • hard-water chelator
  • 19 Trisodium Ethylenediamine Disuccinate
    General function

    A readily biodegradable chelator used in place of EDTA to bind hard-water minerals.

    Estimated lower-concentration zone

    It appears around or below the estimated 1% line, where label order no longer indicates relative amount; its role may be minor or technical.

    May suitBuild-up-sensitive routines

    Binds the calcium and magnesium in hard water, which is what stops mineral deposits accumulating on the strand wash after wash.

    May suitGray, silver, or brass-prone hair

    Copper and iron carried in tap water deposit on the strand and read as a dull, warm cast on gray or light hair. A chelator holds those metals in solution so the wash carries them off.

    PubChem
    • hard-water chelator
  • 20 Xylitol
    General function

    A sugar alcohol that binds water and gives a light, non-sticky moisturised feel.

    Estimated lower-concentration zone

    It appears around or below the estimated 1% line, where label order no longer indicates relative amount; its role may be minor or technical.

    May suitDry, coarse, or high-porosity hair

    High-porosity hair loses water fast; a humectant holds some of it in place for longer than the wash itself would.

    May suitVery dry or highly damaged hair

    Binds water into the outer layers of the strand, and water is what makes dry hair flexible again rather than brittle.

    DependsClimate-sensitive or frizz-prone hair

    A humectant moves water in whichever direction the air allows: it holds moisture in humid conditions and can pull it back out of hair in very dry ones.

    PubChem
    • humectant
  • 21 Sorbic Acid
    • preservative
  • 22 Phenoxyethanol
    • preservative
  • 23 Ethylhexylglycerin
    General function

    A preservative booster that also adds a little softness. Almost always paired with phenoxyethanol.

    Estimated lower-concentration zone

    It appears around or below the estimated 1% line, where label order no longer indicates relative amount; its role may be minor or technical.

    May suitFrizz-prone, damaged, or high-friction hair

    Emollients fill and smooth the surface of the strand, which lowers the friction that lifts the cuticle and reads as roughness.

    PubChem
    • preservative
    • emollient
  • 24 Sodium Benzoate
    • preservative
  • 25 Fragrance · fragrance (parfum)
    General function

    An undisclosed blend of scent ingredients. Regulations let it stay unlisted, so a fragrance-free product is the only way to be certain what is not in it.

    Estimated lower-concentration zone

    It appears around or below the estimated 1% line, where label order no longer indicates relative amount; its role may be minor or technical.

    May not suitFragrance-sensitive routines

    Declared fragrance. On a fragrance-sensitive routine this is the line that decides it, wherever it sits on the label.

    • fragrance
    • declared fragrance
  • 26 Citral
    General function

    A lemon-scented fragrance component listed separately as a recognised allergen.

    Estimated lower-concentration zone

    It appears around or below the estimated 1% line, where label order no longer indicates relative amount; its role may be minor or technical.

    May not suitFragrance-sensitive routines

    One of the 26 scent components the EU requires to be named individually above a threshold. It is named because it is a known contact allergen, not because it is unusual.

    PubChem
    • fragrance
    • named fragrance allergen
  • 27 Citronellol
    General function

    A rose-like fragrance component named separately as a recognised allergen.

    Estimated lower-concentration zone

    It appears around or below the estimated 1% line, where label order no longer indicates relative amount; its role may be minor or technical.

    May not suitFragrance-sensitive routines

    One of the 26 scent components the EU requires to be named individually above a threshold. It is named because it is a known contact allergen, not because it is unusual.

    PubChem
    • fragrance
    • named fragrance allergen
  • 28 Hexyl Cinnamal
    General function

    A jasmine-like fragrance component named separately as a recognised allergen.

    Estimated lower-concentration zone

    It appears around or below the estimated 1% line, where label order no longer indicates relative amount; its role may be minor or technical.

    May not suitFragrance-sensitive routines

    One of the 26 scent components the EU requires to be named individually above a threshold. It is named because it is a known contact allergen, not because it is unusual.

    PubChem
    • fragrance
    • named fragrance allergen
  • 29 Limonene
    General function

    A citrus-smelling fragrance component that EU rules require to be named separately because some people react to it.

    Estimated lower-concentration zone

    It appears around or below the estimated 1% line, where label order no longer indicates relative amount; its role may be minor or technical.

    May not suitFragrance-sensitive routines

    One of the 26 scent components the EU requires to be named individually above a threshold. It is named because it is a known contact allergen, not because it is unusual.

    PubChem
    • fragrance
    • named fragrance allergen
  • 30 Linalool
    General function

    A floral fragrance component listed separately as a recognised contact allergen.

    Estimated lower-concentration zone

    It appears around or below the estimated 1% line, where label order no longer indicates relative amount; its role may be minor or technical.

    May not suitFragrance-sensitive routines

    One of the 26 scent components the EU requires to be named individually above a threshold. It is named because it is a known contact allergen, not because it is unusual.

    PubChem
    • fragrance
    • named fragrance allergen

What the whole list adds up to

  • 8 humectants
  • 6 fragrances
  • 5 named fragrance allergens
  • 4 preservatives
  • 3 conditioning agents
  • 3 film formers
  • 3 polymers
  • 2 solvents
  • 2 conditioning agents
  • 2 gums
  • 2 botanical extracts
  • 2 hard-water chelators
  • 1 cleanser
  • 1 vitamin

Ingredient list captured 2026-08-27. Formulas change — check the package in your hand when an ingredient matters to you.

Price · 3 oz

Seen at $29.99 1 store · checked Aug 28
Show the price ladder
Where we’ve seen it1 listing · 1 store
  • Target
    $29.99
    3 oz · $10.00/oz
    Aug 28Lowest per oz

Sorted by price per ounce. Dated observations from our research, not live prices. Direct store pages, no affiliate links. We don’t sell this product.

How we work this out
  1. 3 oz is the size stores list most often; every comparison on this page is made at it. Other sizes are shown in the Sizes row and the store list.
  2. Seen at $29.99 is the price we have observed for the 3 oz. We need three stores before we call a price commonly seen.
  3. About $28 is what serums typically cost at this size. Too few of the products that do the same job carry a price for us to draw a good-value line.

Formula

Formula score
5 of 10

Nothing separates this from the middle of the range for serums, on formula or on cost per ounce.

How the score is counted
  • Costs more per ounce than 53% of the 79 serums we’ve priced
  • No shine system in the formula
  • Salon tier, sold at Target
  • Salon tier
  • A shine systemThe silicone, oil, or ester that produces gloss.3 pts
  • A weightless carrierDelivers the shine without leaving grease.2 pts
  • Oils or butters in the working zoneSoftens the strand rather than just coating it.2 pts
  • An antioxidantKeeps the oils in the bottle from going off.1 pt
  • No drying alcohol in the first threeFast drying without leading on alcohol.1 pt
  • Fragrance kept out of the top eightScent as a finishing touch, not a major share.1 pt

The formula score is completeness for the job: the share of the systems this product type is normally built around that we can find in this list, weighted. It is not efficacy, not quality, and it never compares across product types.

Similar products

Suits every hair pattern

Final decision

Should you buy it?

Only for a specific need
Best user

People who want maximum slip — for real detangling slip

Biggest tradeoff

Not ideal for anyone sensitive to fragrance, anyone who will not scrunch out a cast, or hair that reads dull

Best alternative if not

Nothing in our library matches it closely at a lower price.

We do not sell products or take placement fees. This page states what the formula and the prices show; the consultation is what matches it to a person.

Reviewers

What people report

Recurring themes our researchers wrote in their own words from sourced reviews. We do not store or scrape star ratings.

Provides effective heat protection while delivering moisture and protecting from heat damage.

Serum makes hair feel excessively heavy like bacon grease and never fully dries out completely.

Serum effectively solves frizz problems with excellent frizz reduction and smoothing results.

Lightweight serum formula does not weigh down hair or leave greasy buildup on fine hair.

Despite nourishing claims product actually dries hair out making it brittle and straw-like.

More from OLAPLEX

How this page was made

  • Everything above is generated from our researched product record — identity, the ingredient list as printed, the brand's own claims, dated price observations, and review themes written in our researchers' own words. No part of this page is written per product.
  • The value band is a fixed label over two stored numbers: this product’s cost per ounce as a percentile of every product of this type we have priced, each at the size it is most often sold in, and how many products we score as doing the same job cost at least a quarter less per ounce.
  • Both scores out of ten are defined on this page. The formula score is completeness for the job, computed from a fixed per-format checklist shown beneath the gauge; the price score is cost per ounce against every product of this type we have priced.
  • The "Is this right for you?" panel reads only your own consultation answers, and it applies exactly the filters our recommendation engine applies. It is computed when you load the page and is never stored on it.
  • 3 sources consulted for this product (0 manufacturer or regulatory, 2 retailer, 1 editorial), last checked 2026-09-05.
  • Ingredient references are linked for 17 of 23 product-aware annotations on this page. Fit notes are conditional formulation guidance, not a conclusion about the finished product or about you.
  • We have not tested this product in a lab and we do not physically test your hair. Formula readings come from the ingredient list; behaviour claims are labelled as the brand's.
  • Ingredient order tells you relative amount only above roughly 1%. Prices are observations on the dates shown and change without notice.
  • Ingredient names link to our ingredient library, where each entry shows what it does, which product types use it, and where it usually sits on a label across everything we have researched.
  • This is cosmetic information, not medical advice, and nothing here diagnoses or treats a health condition.
  • Formula readings: derivation v22. Record last updated 2026-09-05.