Reverses damage as the second step of the K18REPAIR professional service
Protein sits in the first eight ingredients.
- Behentrimonium Chloride
- SH-Oligopeptide-78
- Hydrolyzed Wheat Protein
Supported
Reinforces a damaged strand.
Product image coming soon
K18
Pro Molecular Repair Hair Mask
Mask / Weekly treatment, lean
- Mask / treatment
- Sulfate-free
- Silicone-free
- Moisture-rich
- Vegan · label states
- Cruelty-free · label states
Scent:
The ingredient list declares fragrance. What it smells of is not stated, and we do not guess.
Listing used for research: costco.com
Personal fit
Is this right for you?
Complete the consultation to see exactly how well this product fits your hair and your goals. With 2,400+ products in our library we can match exactly the right products to you.
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- Every product matched against your hair across the 21 factors we check.
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- Your goals, scalp, damage history, water, budget, and scent preferences all shape your plan.
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Factor
Your profile
Fit
Best for hair types
All types
Not in your profile
Moisture level
High
Not in your profile
Oils and butters
None
Not in your profile
Slip / detangling
High
Not in your profile
Weight on hair
Medium
Not in your profile
Fragrance
Present
Not in your profile
Protein
Prominent
Not in your profile
Silicone / wax buildup
None
Not in your profile
Clarifying wash needed
Low
Not in your profile
Parabens / preservatives
None of these listed
Not in your profile
Show all 21 factors we check
The rest of what your plan weighs on this product.
Essential oils
None listed
Not in your profile
Fast-drying alcohol
High
Not in your profile
Vegan / cruelty-free
Vegan · label statesCruelty-free · label states
Not in your profile
Animal-derived ingredients
Vegan · label states
Not in your profile
Heavy humectants
Heavy
Not in your profile
Hard-water defence
None
Not in your profile
UV filter
None listed
Not in your profile
pH adjusted
Adjusted
Not in your profile
Ingredient list
23 ingredientsAbout average
Not in your profile
Price tier
Prestige
Not in your profile
Where to buy it
Salons · Grocery / mass
Not in your profile
The consultation builds your hair profile, then reads every factor in this table against it — and tells you where this product fits, or what to use instead.
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Your avoid-list
Same job for less elsewhere
$13.83/oz at 5 oz — more than 98% of the 341 masks and treatments , which mostly run $1.63–5.59/oz.
Great for
Protein-hungry hairthat stretches and stays stretched when wet
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 carries a scent
Protein-sensitive hairthat goes stiff or straw-like on protein
Very dry or damaged hairit contains fast-drying alcohol
Dry or very humid airwhere heavy humectants work against you
Tight budgetsit sits in the upper price tiers
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.
Weight on the hair
Medium
Middle of the range — noticeable on fine hair, light on coarse hair.
Protein
Prominent
Protein high in the list — a strengthening formula, not a moisture one.
Water-binding (humectants)
High
Humectants near the top — water-binding is a headline mechanism here.
Slip and detangling
High
Conditioning agents sit high in the list — this is a detangling formula.
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.
| Ingredient | What it does | Why it matters | Chip |
|---|---|---|---|
| WaterWater (Aqua) (Eau) | solvent | The base everything else is dissolved in | Neutral |
| Alcohol Denat. | drying alcohol | Speeds drying — and can read dry on the hair | Drying |
| Propylene Glycol | humectant | Pulls water into the hair | Moisturizes |
| Cetearyl Alcohol | fatty alcohol | Thickens and conditions — not a drying alcohol | Softens |
| Dicaprylyl Ether | light ester | Light slip without much weight | Softens |
| Cetyl Esters | light ester | Light slip without much weight | Softens |
| Behentrimonium Chloride | conditioning agent | Conditions and softens — this is what makes it comb through | Detangles |
| Polysorbate 20 | solubilizer | Keeps oils dissolved in water | Stabilizes |
| SH-Oligopeptide-78 | protein | A small amount of protein | Protein |
| Hydrolyzed Wheat Protein | film former | A supporting film former | Protein |
| Isopropyl Alcohol | drying alcohol | A small amount, for fast drying | Drying |
| FragranceFragrance (Parfum) | fragrance | The scent | Fragrance |
What the list leaves out, and what it carriesThe list carries no sulfates or silicones. Protein sits high: this is a strengthening step rather than a moisture one. Fragrance is on the label. Contains fast-drying alcohol.
Full ingredient list (23)
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 ingredientListed in the first three ingredients, it is likely a structural part of this formula.
- solvent
-
2
Alcohol Denat.
General function
Fast-drying alcohol used to make sprays set quickly. In leave-on products it can leave hair feeling dry, especially in high position on the list.
Leading ingredientListed in the first three ingredients, it is likely a structural part of this formula.
PubChemMay suitFine or easily flattened hairEvaporates on contact, which is how a spray sets almost instantly and leaves no weight behind it.
May not suitDry, coarse, or high-porosity hairPorous hair gives water up easily as it is; a fast-evaporating solvent high on the list accelerates that.
May not suitVery dry or highly damaged hairIt evaporates quickly and takes some water with it. On hair already short of moisture, a formula built on a lot of it can finish drier than it started.
- drying alcohol
- solvent
-
3
Propylene Glycol
General function
A small humectant and solvent that keeps formulas stable and helps active ingredients spread.
Leading ingredientListed in the first three ingredients, it is likely a structural part of this formula.
PubChemMay suitFine or easily flattened hairLight and water-binding rather than oily, so it hydrates without contributing weight.
May suitVery dry or highly damaged hairA small water-binding solvent. It holds moisture and helps the rest of the formula spread evenly over the strand.
DependsClimate-sensitive or frizz-prone hairA 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.
- humectant
- solvent
-
4
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.
Supporting ingredientListed in positions 4–8, it likely makes a meaningful contribution alongside the formula's main ingredients.
PubChemMay suitDry, coarse, or high-porosity hairThe waxy solid that gives a conditioner its body. It deposits a soft lubricating layer, which is most of what makes hair feel smooth after rinsing.
May suitFrizz-prone, damaged, or high-friction hairDeposits with the cationic conditioners and helps them lie flat along the strand, which is where the detangling actually comes from.
DependsFine or easily flattened hairNear the top of a conditioner it is doing most of the conditioning, and most of the weighting, at the same time.
- fatty alcohol
- emollient
- thickener
-
5
Dicaprylyl Ether
General function
A light emollient used for slip without a greasy after-feel.
Supporting ingredientListed in positions 4–8, it likely makes a meaningful contribution alongside the formula's main ingredients.
PubChemMay suitFine or easily flattened hairA light emollient: it softens the surface with noticeably less weight than an oil or a butter.
May suitFrizz-prone, damaged, or high-friction hairSpreads thin and lowers friction between strands without the heaviness of a fixed oil.
- light ester
- emollient
-
6
Cetyl Esters
General function
A waxy ester blend that replaces spermaceti in creams. It thickens and leaves a smooth, non-greasy finish.
Supporting ingredientListed in positions 4–8, it likely makes a meaningful contribution alongside the formula's main ingredients.
May suitFine or easily flattened hairA light emollient: it softens the surface with noticeably less weight than an oil or a butter.
May suitFrizz-prone, damaged, or high-friction hairSpreads thin and lowers friction between strands without the heaviness of a fixed oil.
- light ester
- emollient
- thickener
-
7
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 ingredientListed in positions 4–8, it likely makes a meaningful contribution alongside the formula's main ingredients.
International Journal of Cosmetic ScienceMay suitDry, coarse, or high-porosity hairElectrokinetic 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 hairA cationic conditioning agent: it binds to the damaged, negatively charged parts of the cuticle and lowers combing friction there.
DependsBuild-up-sensitive routinesSubstantive by design. A routine with no detergent wash gives it nothing to leave with.
- conditioning agent
- cleanser
-
8
Polysorbate 20
General function
Keeps fragrance and oils dissolved in a watery formula so it stays clear.
Supporting ingredientListed in positions 4–8, it likely makes a meaningful contribution alongside the formula's main ingredients.
- solubilizer
- emulsifier
-
9
SH-Oligopeptide-78
General function
A bioengineered peptide used at low levels in scalp and growth-positioned products.
Secondary ingredientLower in the ordered portion of the list, it is more likely playing a supporting role than defining the formula.
DependsVery dry or highly damaged hairUnhydrolysed protein is too large to enter the strand. It sits on the surface, which is a coating effect rather than internal reinforcement.
- protein
-
10
Hydrolyzed Wheat Protein
General function
Wheat protein broken into fragments small enough to cling to the hair. It adds temporary strength and body; too much can feel stiff.
Secondary ingredientLower in the ordered portion of the list, it is more likely playing a supporting role than defining the formula.
May suitFrizz-prone, damaged, or high-friction hairFilling surface gaps evens out the cuticle, which is part of what makes damaged hair comb and reflect light more like undamaged hair.
May suitMaximum-hold stylingFilm formers are what hold a style: they dry into a connected film across the strands so the shape resists movement.
May suitVery dry or highly damaged hairHydrolysed fragments are small enough to sit in the gaps of a worn cuticle for a wash or two, temporarily restoring stiffness and cutting breakage in combing.
- film former
- protein
- hydrolysed protein
-
11
Hydrolyzed Wheat Starch
General function
A starch fragment used for light body and film. It is a carbohydrate, not a protein.
Secondary ingredientLower in the ordered portion of the list, it is more likely playing a supporting role than defining the formula.
May suitFine or easily flattened hairAdds grip and body with no oil attached, which is what lifts fine hair at the root instead of weighing it down.
DependsCurls or waves needing flexible holdHow rigid the finish is depends on which polymer it is and what the formula pairs with it, not on there being one.
DependsMaximum-hold stylingStarch gives texture and grip rather than a set film; firm hold usually needs a polymer alongside it.
- film former
- starch
-
12
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.
Secondary ingredientLower in the ordered portion of the list, it is more likely playing a supporting role than defining the formula.
PubChemMay suitFine or easily flattened hairEvaporates on contact, which is how a spray sets almost instantly and leaves no weight behind it.
- drying alcohol
- solvent
- ▾Below about this point, order stops being meaningful — these are typically used at 1% or less.
-
13
Tocopherol
- antioxidant
- vitamin
-
14
Phenoxyethanol
- preservative
-
15
Potassium Sorbate
- preservative
-
16
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 zoneIt appears around or below the estimated 1% line, where label order no longer indicates relative amount; its role may be minor or technical.
International Journal of TrichologyMay suitBuild-up-sensitive routinesHolds hard-water minerals in solution so they rinse away instead of depositing on the hair.
May suitFrizz-prone, damaged, or high-friction hairThe 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 hairWhere a warm cast comes from water minerals rather than from the hair itself, holding those metals in solution is what removes it.
- pH adjuster
- hard-water chelator
-
17
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 zoneIt 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 routinesDeclared fragrance. On a fragrance-sensitive routine this is the line that decides it, wherever it sits on the label.
- fragrance
- declared fragrance
-
18
Geraniol
General function
A rose-scented fragrance component, listed on its own because some people react to it.
Estimated lower-concentration zoneIt 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 routinesOne 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.
- fragrance
- named fragrance allergen
-
19
Linalool
General function
A floral fragrance component listed separately as a recognised contact allergen.
Estimated lower-concentration zoneIt appears around or below the estimated 1% line, where label order no longer indicates relative amount; its role may be minor or technical.
PubChemMay not suitFragrance-sensitive routinesOne 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.
- fragrance
- named fragrance allergen
-
20
Hexyl Cinnamal
General function
A jasmine-like fragrance component named separately as a recognised allergen.
Estimated lower-concentration zoneIt appears around or below the estimated 1% line, where label order no longer indicates relative amount; its role may be minor or technical.
PubChemMay not suitFragrance-sensitive routinesOne 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.
- fragrance
- named fragrance allergen
-
21
Benzyl Alcohol
- preservative
- solvent
-
22
Amyl Salicylate
General function
A soft floral fragrance component named separately as a recognised allergen.
Estimated lower-concentration zoneIt 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 routinesOne 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.
- fragrance
- named fragrance allergen
-
23
benzaldehyde
General function
An individual aroma chemical. It is part of the product's fragrance; brands that print these are disclosing more of the blend than the rules require.
Estimated lower-concentration zoneIt 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 routinesDeclared fragrance. On a fragrance-sensitive routine this is the line that decides it, wherever it sits on the label.
- fragrance
What the whole list adds up to
- 6 fragrances
- 5 solvents
- 4 named fragrance allergens
- 3 emollients
- 3 preservatives
- 2 drying alcohols
- 2 thickeners
- 2 light esters
- 2 proteins
- 2 film formers
- 1 humectant
- 1 fatty alcohol
- 1 conditioning agent
- 1 cleanser
Ingredient list captured 2026-09-05. Formulas change — check the package in your hand when an ingredient matters to you.
Price · 5 oz
Seen at
$69.16
Good value under
$12
Priced above the products that do the same job. Stores sell it above the $12 line; products that do this job typically go for about $15 at this size.
Show the price ladder
Where we’ve seen it1 listing · 1 store
-
Target (marketplace seller)
$69.165 oz · $13.83/ozSep 5Lowest 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
- 5 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.
- Seen at $69.16 is the price we have observed for the 5 oz. We need three stores before we call a price commonly seen.
- Good value under $12 comes from the 8 products we score as doing the same job as this one. A quarter of them cost less than $2.34/oz; at 5 oz that is $12. Under that line you are paying less than most of them.
- About $15 is what those same products typically cost at this size — the midpoint of their prices per ounce, scaled to 5 oz.
Formula
6
Formula score
6 of 10
Sold through salons at a price 7 products that do the same job undercut — the distribution is part of what you are paying for.
How the score is counted
- 7 products that do the same job cost less per ounce
- Costs more per ounce than 98% of the 341 masks and treatments we’ve priced
- No rich emollients in the formula
- Prestige tier, sold at Salons and Grocery / mass
- Rich emollientsThe depth a treatment step is built around.3 pts
- Conditioning agents up frontWhat makes wet hair comb through.2 pts
- Protein or amino acidsThe strengthening side of a treatment.2 pts
- A humectantBinds water into the hair.1 pt
- A stated dwell timeThe brand says how long to leave it on.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.
Does the same job, for less
Same derived functions — what it cleans, conditions, coats or holds — at a lower cost per ounce. Scent, texture and where you buy it can still differ.
GoldwellClosest function
Dualsenses Bond Pro 60sec Treatment
$2.26/oz $11.57/oz less
- Protein
- Curly method
- Silicone-free
- Function
- Also
Paul MitchellClose function
Bond Rx Step 1 Professional Bond Builder
$8.29/oz $5.54/oz less
- Protein
- Function
- Also
L'Oreal Paris ElviveLowest cost per oz
8 Second Wonder Water Lamellar Hair Treatment
$1.84/oz $11.99/oz less
- Quick
- Budget
- Widely sold
- Function
- Also
See more alternatives in the product library
These are functional neighbours, not personal recommendations — they are close on formula, not chosen for anyone. Get the one that fits your hair, routine, and budget
Final decision
Should you buy it?
Good for the right person, not the lowest costBest user
Soft, over-stretchy hair who want protein high in the formula and real detangling slip
Biggest tradeoff
Not ideal for anyone sensitive to fragrance, hair that stiffens on protein, or very dry or high-damage hair
Best alternative if not
Goldwell Dualsenses Bond Pro 60sec Treatment, 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, against what the formula shows
Claims are quoted from the brand. We only mark one supported, partly supported, or conflicting when the ingredient list actually speaks to it; everything else stays "stated by the brand", which is not a criticism — most claims simply cannot be read off a label.
3
SupportedBacked by ingredients
0
Partly supportedSome supporting logic
3
Stated by brandNo clear evidence
0
Potential conflictFormula works against claim
Repairs damage from bleach, color, chemical services and heat
Protein sits in the first eight ingredients.
- Behentrimonium Chloride
- SH-Oligopeptide-78
- Hydrolyzed Wheat Protein
Supported
Reinforces a damaged strand.
Reconnects broken polypeptide chains and disulfide bonds
Protein sits in the first eight ingredients.
- Behentrimonium Chloride
- SH-Oligopeptide-78
- Hydrolyzed Wheat Protein
Supported
Reinforces a damaged strand.
Restores elasticity and strength in 4 minutes
This is a marketing claim; an ingredient list cannot speak to it.
—
Stated by brand
Can’t be confirmed from label.
Clinically proven damage reversal
A brand-run study. We report it as stated and do not repeat the number as fact.
—
Stated by brand
Only the brand’s testing shows this.
Works on all hair types
No formula reads the same on every texture; our fit panel is the better guide.
—
Stated by brand
See the fit panel instead.
How to read this
We look at the first 10–15 ingredients and what they do in a formula — not marketing. If the list doesn't speak to a claim, we don't assume.
Reviewers
What people report
Recurring themes our researchers wrote in their own words from sourced reviews. We do not store or scrape star ratings.
Stylists frequently describe visibly repairing severely damaged or over-processed hair, especially on blonde and lightened clients, within a single treatment.
Reviewers commonly describe the result as hair that feels noticeably stronger, shinier and softer right after the four-minute application.
Many reviewers say their clients specifically ask for this treatment again after their first experience with it.
More from K18
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 (1 manufacturer or regulatory, 1 retailer, 1 editorial), last checked 2026-09-06.
- Ingredient references are linked for 9 of 17 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 2026-09-06.