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Biolage · Smooth Proof

Smooth Proof Conditioner

Conditioner / Everyday rinse-out, detangling

  • Conditioner
  • Sulfate-free
  • Silicone-free
  • Protein-free
Size8 fl oz (236 ml)usual store size · 2 sizes
Price$45seen at one store · 33.8 oz
Price / oz$1.36/ozat 33.8 oz
Where to buy3 stores · $45.00–47.18

Add it to your products. We’ll tell you if it’s ever recalled.

Scent:

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

Strength: Strong

Listing used for research: target.com

Personal fit

Is this right for you?

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Priced with its peers

$1.36/oz at 33.8 oz, less than 60% of the 1119 conditioners , which mostly run $0.94–3.41/oz. The cost less.

Price and stores

Great for

Protein-sensitive hairthat stiffens when protein is added
Maximum slipfor hair that tangles the moment it is wet
Dry, thirsty hairhumectants and emollients both sit up front
Curly-method routinesno sulfates and no water-insoluble silicones
Silicone-free routinesno silicones appear in the list
Cuticle-smoothing pHa pH adjuster brings it to the acidic range hair prefers

Maybe skip if

this product has a strong scent
Very dry or damaged hairit contains fast-drying alcohol
Hair that needs proteinthere is none in this list
Dry or very humid airwhere heavy humectants work against you
Tight budgetsit sits in the upper price tiers

Whether this much richness suits you depends on your strand thickness, porosity and how easily your hair goes flat. We work that out in the consultation.

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.

Slip and detangling High

Conditioning agents sit high in the list, so this is a detangling formula.

Oils and butters Present, high in the list

Oils sit high in the list: a softening, coating formula.

Weight on the hair Medium

Middle of the range: noticeable on fine hair, light on coarse hair.

Water-binding (humectants) High

Humectants near the top: binding water is one of its main jobs.

Protein None

No protein or amino acids in the list.

Needs detergent to remove No

Nothing here needs a detergent wash to remove.

Hard-water defence None

No chelating agent in the list.

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. The 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
WaterAqua/water/eau solvent The base everything else is dissolved in Neutral
Cetearyl Alcohol fatty alcohol Thickens and conditions (not a drying alcohol) Softens
Elaeis Guineensis Oil/Palm Oil oil Coats and softens the strand Softens
Behentrimonium Chloride conditioning agent Conditions and softens so hair combs through Detangles
Glycerin humectant Pulls water into the hair Moisturizes
Phenoxyethanol preservative Keeps the product from spoiling Stabilizes
Isopropyl Alcohol drying alcohol A small amount, for fast drying Drying
Stearamidopropyl Dimethylamine conditioning agent Adds slip, lower in the list Detangles
FragranceParfum/fragrance fragrance The scent Fragrance
Limonene fragrance The scent Fragrance
What the list leaves out, and what it carriesNo sulfates or silicones. Protein-free: this is built for moisture rather than for strengthening. Contains fragrance. Fast-drying alcohol is in the list.
Full ingredient list (14)

In the US, ingredients above 1% are listed from most to least. Below 1% they can appear in any order. Each note keeps three things apart: what the ingredient generally does, its role in this type of product, and what its position can tell you.

  • 1 Water · Aqua/water/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 Cetearyl Alcohol
    General function

    A waxy fatty alcohol - nothing like drying alcohol. It gives conditioners their body and leaves a soft, smoothing film on the hair.

    Role in this product type

    In conditioner, cetearyl alcohol gives the emulsion its creamy structure and helps it spread evenly through the hair. Its emollient layer adds slip and a smoother feel.

    Leading ingredient

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

    May suitDry, coarse, or high-porosity hair

    May suit dry, coarse, or high-porosity hair that benefits from added slip and a more substantial conditioning film.

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

    Deposits with the cationic conditioners and helps them lie flat along the strand, which is where the detangling actually comes from.

    DependsFine or easily flattened hair

    Consider if hair is fine or easily flattened: a formula built heavily around fatty alcohols can feel richer than a lightweight conditioner.

    BASF
    • fatty alcohol
    • emollient
    • thickener
  • 3 Elaeis Guineensis Oil/Palm Oil
    General function

    Palm oil, a heavy, sealing plant oil used in rich creams and butters.

    Leading ingredient

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

    May suitDry, coarse, or high-porosity hair

    Coats the surface and slows water leaving the strand, which is usually what coarse hair that dries out fast is missing.

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

    A thin oil layer lowers friction between strands and flattens the raised cuticle that scatters light and catches on its neighbours.

    May not suitFine or easily flattened hair

    Near the top of a list an oil is weight before it is anything else, and fine hair shows that first at the roots.

    • oil
    • emollient
  • 4 Behentrimonium Chloride
    General function

    A positively charged conditioning agent that binds to damaged, negatively charged spots on the hair. It is the main detangling ingredient in most rinse-out conditioners.

    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

    Electrokinetic measurement puts the C22 quat ahead of the C16 ones for deposition: the longer chain adds van der Waals stabilisation on top of the charge binding. That extra deposit is what coarse hair usually needs to comb through.

    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
  • 5 Glycerin
    General function

    Glycerin, also called glycerol, attracts moisture and mixes completely with water.

    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

    Water moves both ways. Measured across concentrations, glycerin solutions give water up in some conditions and take it from the air in others. What it does for you depends on how much of it is there and on the air around it.

    Scientific Reports
    • humectant
  • ▾Below about here, the order stops meaning much. These are usually used at 1% or less.
  • 6 Phenoxyethanol
    General function

    The most common modern preservative; it keeps the product free of bacteria and mould. It sits well below 1% of the formula.

    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.

    PubChem
    • preservative
  • 7 Isopropyl Alcohol
    General function

    A fast-evaporating alcohol used as a solvent and to speed drying. Well down the list it is a processing aid; near the top it can leave hair feeling dry.

    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 suitFine or easily flattened hair

    Evaporates on contact, which is how a spray sets almost instantly and leaves no weight behind it.

    PubChem
    • drying alcohol
    • solvent
  • 8 Stearamidopropyl Dimethylamine
    General function

    A gentle conditioning agent activated by the acid in the formula. It smooths the cuticle without much build-up.

    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

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

    May suitVery dry or highly damaged hair

    The class that does the detangling in a conditioner. It deposits lubrication where the cuticle is worn.

    DependsBuild-up-sensitive routines

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

    PubChem
    • conditioning agent
  • 9 Fragrance · Parfum/fragrance
    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
  • 10 Camellia Oleifera Seed Oil
    General function

    Tea seed oil - light, fast-absorbing, used for shine on fine hair.

    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

    Coats the surface and slows water leaving the strand, which is usually what coarse hair that dries out fast is missing.

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

    A thin oil layer lowers friction between strands and flattens the raised cuticle that scatters light and catches on its neighbours.

    • oil
    • emollient
  • 11 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
  • 12 Chlorhexidine Dihydrochloride
    • preservative
  • 13 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
  • 14 Tocopherol
    • antioxidant
    • vitamin

What the whole list adds up to

  • 3 emollients
  • 2 solvents
  • 2 oils
  • 2 conditioning agents
  • 2 preservatives
  • 2 fragrances
  • 1 fatty alcohol
  • 1 thickener
  • 1 cleanser
  • 1 humectant
  • 1 drying alcohol
  • 1 declared fragrance
  • 1 pH adjuster
  • 1 hard-water chelator

Ingredient list captured 2026-10-01. Formulas change, so check the package in your hand when an ingredient matters to you.

Price · 33.8 oz

Seen at $45 lowest of 2 stores · checked Aug 29
Good value under $34 Under $1.00/oz it costs less than three-quarters of the 8 products we score as doing the same job

Priced above the products that do the same job. Stores sell it above the $34 line; products that do this job typically go for about $48 at this size.

Show the price ladder
Where we’ve seen it2 listings · 2 stores

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. 33.8 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 $45 is the price we have observed for the 33.8 oz. We need three stores before we call a price commonly seen.
  3. Good value under $34 comes from the 8 products we score as doing the same job as this one. A quarter of them cost less than $1.00/oz; at 33.8 oz that is $34. Under that line you are paying less than most of them.
  4. About $48 is what those same products typically cost at this size: the midpoint of their prices per ounce, scaled to 33.8 oz.

Formula

Formula score
10 of 10

The formula carries the systems a conditioner is built around, and it sits in the middle of the range for conditioners per ounce.

How the score is counted
  • 2 products we score as doing the same job cost less per ounce
  • Costs less per ounce than 60% of the 1119 conditioners we’ve priced
  • Covers 6 of the 6 things a conditioner should do
  • Reviewers mention 2 things they like about how it performs
  • Conditioning agents up frontWhat makes wet hair comb through.3 pts
  • Oils or butters in the working zoneSoftens the strand rather than just coating it.2 pts
  • Slip for detanglingReduces the force it takes to comb wet hair.2 pts
  • A humectantBinds water into the hair.1 pt
  • A pH adjusterBrings the formula to the acidic pH hair prefers.1 pt
  • Fragrance kept out of the top eightScent as a finishing touch, not a major share.1 pt

The formula score measures completeness for the job: a weighted share of the systems this product type is usually built around that we find in this list. It does not rate how well the product works or its quality, and it never compares across product types.

Does the same job, for less

Formulas that do the same things (cleanse, condition, coat or hold) for less per ounce. Scent, texture and where you buy them can still differ.

MatrixLowest cost per oz Glow Mania Color Protecting Conditioner $0.50/oz $0.86/oz less
  • Protein-free
  • Curly method
  • Silicone-free
· Same function
Differs
  • Masstige tier
  • 1.7 oz bottle
Compare
Garnier FructisSame function Whole Blends Moisturizing Conditioner with Coconut Water & Aloe Vera $0.52/oz $0.84/oz less
  • Protein-free
  • Curly method
  • Silicone-free
Differs
  • Drugstore tier
  • 12.5 oz bottle
Compare

See more alternatives in the product library

These products do a similar job. We haven’t matched them to you. Find the one that fits your hair, routine and budget

Suits every hair pattern

Final decision

Should you buy it?

A solid pick for the hair it suits
Best user

Hair that stiffens on protein, for a protein-free formula and real detangling slip

Biggest tradeoff

Worth skipping for anyone sensitive to fragrance, very dry or high-damage hair, or soft, over-stretchy hair that needs protein

Best alternative if not

Matrix Glow Mania Color Protecting Conditioner for similar results 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.

Claims check

What the brand says, and what the formula shows

Claims are quoted from the brand. We mark a claim supported, partly supported or conflicting only when the ingredient list speaks to it. Everything else stays "stated by the brand". That isn’t a criticism: most claims can’t be checked from a label.

3
SupportedBacked by ingredients
0
Partly supportedSome supporting logic
0
Stated by brandNo clear evidence
0
Potential conflictFormula works against claim
Smooths and nourishes naturally prone frizzy hair

Humectants or rich emollients sit in the first eight ingredients.

  • Cetearyl Alcohol
  • Elaeis Guineensis Oil/Palm Oil
  • Glycerin
Supported

Helps hair feel hydrated.

Instantly detangles and leaves hair more manageable

Conditioning agents that reduce combing force sit high in the list.

  • Cetearyl Alcohol
  • Behentrimonium Chloride
  • Stearamidopropyl Dimethylamine
Supported

Easier detangling, less breakage.

Provides hydration without weighing hair down

Humectants or rich emollients sit in the first eight ingredients.

  • Cetearyl Alcohol
  • Elaeis Guineensis Oil/Palm Oil
  • Glycerin
Supported

Helps hair feel hydrated.

How to read this

We look at the first 10–15 ingredients and what they do in a formula, not at the marketing. If the list doesn't speak to a claim, we don't assume.

Reviewers

What people report

Themes that come up again and again in sourced reviews, written by our researchers in their own words. We don’t store or scrape star ratings.

Multiple reviewers praise the scent as pleasant and long-lasting

general users

Reviewers with fine or coarse/curly hair report fuller, bouncier, healthier-looking hair and effective frizz control after regular use

fine hair and coarse/natural-textured hair users

A recurring complaint that a package-size reduction (reviewers describe roughly 40% less product) at the same price amounts to shrinkflation

long-time repeat buyers

Some reviewers report a reformulation (not just packaging) left hair drier and less smooth than the version they remembered

long-time users comparing to an earlier formula

A subset of reviewers find the smoothing/frizz-control effect underwhelming relative to expectations set by marketing or a sample

users trying the product after a sample or on high-frizz hair

More from Biolage

How this page was made

  • Everything above comes from our researched product record: identity, the ingredient list as printed, the brand's own claims, dated prices and review themes our researchers wrote in their own words. No part of this page is written by hand for one 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.
  • 6 sources consulted for this product (3 manufacturer or regulatory, 3 retailer, 0 editorial), last checked 2026-10-01.
  • Ingredient references are linked for 7 of 10 product-aware annotations on this page. Fit notes are general formulation guidance. They aren’t a verdict on the finished product or on you.
  • We haven’t tested this product in a lab, and we don’t physically test your hair. Formula readings come from the ingredient list. Claims about how it behaves are labelled as the brand's.
  • Ingredient order tells you relative amount only above roughly 1%. Prices are what we saw on the dates shown and can change.
  • 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 v23. Record last updated 2026-09-02.

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