Skip to main content

Side by side

Kerastase Genesis Defense Thermique Blow Dry Primer vs Redken Extreme Length Leave-In Conditioner

87% function match · 7 of the 10 functions we compared match Formula overlap 51%. Kerastase Genesis Defense Thermique Blow Dry Primer and Redken Extreme Length Leave-In Conditioner share 4 ingredients among each other's most prominent.

These sit in different steps of a routine — Kerastase Genesis Defense Thermique Blow Dry Primer is a heat protectant and Redken Extreme Length Leave-In Conditioner is a leave-in. Comparing their formulas is fair; treating one as a replacement for the other is not.

Based on your consultation

Which of these fits your hair?

We check your pattern, moisture need, scalp, fragrance tolerance, weight sensitivity and more against each formula — and say which one lines up.

Your profile at a glance

  • Your answers appear here
  • Your answers appear here
  • Your answers appear here
  • Your answers appear here

When each one is the right call

What each formula is built for, from its own ingredient list.

  • Genesis Defense Thermique Blow Dry Primer — heat styling
  • Extreme Length Leave-In Conditioner — maximum slip

Side by side

Every trait, aligned

One row per trait, read from each product’s own ingredient list and record. A dash means we have not researched that field for that product — it is not a “no”.

Trait
Kerastase Genesis Defense Thermique Blow Dry Primer — 5.1 oz container Kerastase

Genesis Defense Thermique Blow Dry Primer

  • Heat protectant
  • Prestige
  • Sulfate-free
  • Moisture-rich
Redken

Extreme Length Leave-In Conditioner

  • Leave-in
  • Salon
  • Sulfate-free
Price, size & price per ounce
$50 5.1 oz · $9.80/oz
$34 5.1 oz · $6.67/oz
Value / price positioning
Same job for less elsewhere $$$$$ Prestige tier · costs more than 94% of the 553 heat protectants we’ve priced
Same job for less elsewhere $$$$$ Salon tier · costs more than 82% of the 481 leave-ins we’ve priced
Best for hair types
Curly–Coily A heavy formula: coarse, curlier strands carry it without flattening. Your hair
All types Nothing in the formula or the claims narrows this to one pattern. Your hair
Moisture level Same
Moderate Humectants in the working part of the formula. Your hair
Moderate Humectants in the working part of the formula. Your hair
Heat protection
Moderate Sold as a heat protectant; no temperature is stated. Your hair
—
Slip / detangling Same
High Conditioning agents sit high in the list — this is a detangling formula. Your hair
High Conditioning agents sit high in the list — this is a detangling formula. Your hair
Weight on hair Differs
Rich Heavy butters and waxes in the first eight ingredients. Your hair
Medium Middle of the range — noticeable on fine hair, light on coarse hair. Your hair
Fragrance
Present Fragrance is listed; it sits below the working ingredients. Your hair
Present Fragrance is listed; it sits below the working ingredients. Your hair
Protein Same
Minor Protein appears, low enough to be a supporting ingredient. Your hair
Minor Protein appears, low enough to be a supporting ingredient. Your hair
Silicone / wax buildup Same
High Water-insoluble silicones or waxes: a detergent wash is what removes them. Your hair
High Water-insoluble silicones or waxes: a detergent wash is what removes them. Your hair
Clarifying wash needed
Moderate Your hair
Moderate Your hair
Oils and butters Differs
—
Low Oils are present, but low enough to be a finishing touch. Your hair
Fast-drying alcohol Same
Present Fast-drying alcohol is present — it speeds drying and can read dry on the hair. Your hair
—
Formula completeness
out of 10
Complete for its job
out of 10
Complete for its job
Who should choose this
  • Heat stylingthe brand positions this as a heat protectant
  • Maximum slipfor hair that tangles the moment it is wet
  • Dry, thirsty hairhumectants and emollients both sit up front
  • Coarse or dry hairthat absorbs everything you give it
  • Maximum slipfor hair that tangles the moment it is wet
  • Curl definitionfilm formers hold a clump together
  • Porous, damaged hairceramides are in the list
  • Cuticle-smoothing pHa pH adjuster brings it to the acidic range hair prefers
Why you might skip it
  • Scents bother youthis product carries a strong scent
  • Curly-method routinesthese silicones need a detergent to remove
  • Oily scalp or fine hairthat gets weighed down
  • Scents bother youthis product carries a light scent
  • Curly-method routinesthese silicones need a detergent to remove
  • Very dry or damaged hairit contains fast-drying alcohol
from the formula stated by the brand reported by reviewers Scale: 1 dot low · 5 dots high, within this product type.
More facts about each one
Type
Heat protectantspray
Leave-in
Where to buy
Brand website · Target · Amazon
—
Free of
  • sulfate-free
  • sulfate-free
Cruelty-free
Not cruelty-free · PETA-listed
Not cruelty-free · PETA-listed
Scent
Scented, not described
Scented, not described
Heat protection
Claimed, no temperature stated
—

Facts as we recorded them. A dash means we have not researched that field for that product — it is not a "no".

The bottom line

The bottom line depends on your hair

Which of these two suits you is a question about your hair, not about them. The consultation answers it — and tells you what your routine needs around it.

Take the consultation

$49.00 once, for your consultation and hair profile. No subscription, no required purchases.

The detail behind the table

Where the readings above come from: the ingredient lists themselves, each brand’s claims checked against them, what owners report, and cost per ounce in context.

Shared and distinct ingredients

Shared and distinct ingredients

Computed from the ingredient lists as printed. "Shared" means both lists carry it; where it sits on each label is stated, because position is what tells you how much.

What both formulas carry

IngredientGenesis Defense Thermique Blow Dry PrimerExtreme Length Leave-In Conditioner
Water
Neutral
#1Leading
#1Leading
Amodimethicone
Buildup
#3Leading
#2Leading
Polyquaternium-37
Detangles
#4Supporting
#5Supporting
Phenoxyethanol
Stabilizes
#5Below the 1% line
#6Below the 1% line
Propylene Glycol Dicaprylate/Dicaprate
Softens
#6Below the 1% line
#7Below the 1% line
Sodium Hydroxide
pH balancer
#8Below the 1% line
#10Below the 1% line
Limonene
Fragrance
#15Below the 1% line
#30Below the 1% line
Linalool
Fragrance
#19Below the 1% line
#32Below the 1% line
Isopropyl Alcohol
Drying
#20Below the 1% line
#39Below the 1% line
Fragrance
Fragrance
#37Below the 1% line
#9Below the 1% line
Benzyl Benzoate
Fragrance
#30Below the 1% line
#27Below the 1% line

What only one of them carries

Genesis Defense Thermique Blow Dry Primer

Extreme Length Leave-In Conditioner

Full ingredient list — Genesis Defense Thermique Blow Dry Primer (37)
Full ingredient list — Extreme Length Leave-In Conditioner (40)

Claims check

What each brand says, against what each formula shows

Claims are quoted from each brand. We only mark one supported, partly supported, or conflicting when that product’s ingredient list actually speaks to it.

VerdictsGenesis Defense Thermique Blow Dry PrimerExtreme Length Leave-In Conditioner
Supported
1
1
Partly supported
2
1
Stated by brand
3
2
Potential conflict
0
0

Genesis Defense Thermique Blow Dry Primer

  • Lightweight leave-in spray to strengthen, heat protect, and prevent breakagePartly supportedSupports the surface, not a treatment.
  • 97% less hair fall due to breakage from brushingStated by brandOnly the brand’s testing shows this.
  • 89% more nourished hairStated by brandOnly the brand’s testing shows this.
  • 88% more smooth/conditionedStated by brandOnly the brand’s testing shows this.
  • Strengthens Hair Weakened from Brushing and Over-StylingPartly supportedSupports the surface, not a treatment.
  • Up to 24 Hours of Frizz ProtectionSupportedSmoother strands, less frizz.

Extreme Length Leave-In Conditioner

  • Strengthens damaged hair to grow longer and strongerPartly supportedSupports the surface, not a treatment.
  • Reduces breakage by 81% (when using complete system)Stated by brandOnly the brand’s testing shows this.
  • Visibly reduces split end appearance by 78% (when using complete system)Stated by brandOnly the brand’s testing shows this.
  • Adds manageability, smoothness, and shineSupportedEasier detangling, less breakage.

What owners say

What people report

Recurring themes our researchers wrote in their own words from sourced reviews. We do not store or scrape star ratings, and we never balance one product’s themes against another’s by inventing them.

Both praised for the scent and frizz control. Redken Extreme Length Leave-In Conditioner draws complaints about dryness and weight.

Genesis Defense Thermique Blow Dry Primer

Hair feels softer, more hydrated, and less frizzy after use

Adopted as a must-use step before blow drying or straightening

Pleasant, long-lasting scent; texture described as lightweight, not heavy or greasy

Frequently noted as expensive, though most say worth it for the results

Extreme Length Leave-In Conditioner

Several reviewers say the product is concentrated and a little goes a long way, making it feel economical despite the premium price.

general Ulta reviewers

Reviewers frequently describe hair as noticeably softer, silkier and less frizzy after use, often mentioning a pleasant lingering scent.

general Ulta reviewers

A recurring complaint is that the product feels sticky, gummy or heavy and leaves hair feeling coated or dirty rather than clean.

general Ulta reviewers

A minority of reviewers report the opposite of the intended effect: dry, rough, or damaged-feeling hair, or increased shedding, after regular use.

general Ulta reviewers

Price check

Cost per ounce, in context

Cost per ounce against every product of this type we have priced, each at the size it is most often sold in. Value labels are computed from that percentile and from how many products that do the same job cost less; they are comparisons, not judgements about a brand.

$6.67/oz vs $9.80/oz — Kerastase Genesis Defense Thermique Blow Dry Primer costs about 1.5× more per ounce than Redken Extreme Length Leave-In Conditioner.

Genesis Defense Thermique Blow Dry Primer

Against 553 heat protectants with a computable unit price.

Extreme Length Leave-In Conditioner

Against 481 leave-ins with a computable unit price.

Value readGenesis Defense Thermique Blow Dry PrimerExtreme Length Leave-In Conditioner
Label
Same job for less elsewhereYou are paying above the range for a formula close to several lower-priced options.
Same job for less elsewhereYou are paying above the range for a formula close to several lower-priced options.

Computed from cost per ounce against every product of this type we have priced, and from how many products that do the same job cost less. It is a comparison, not a judgement about the brand.

Compare with something else

Close formulas to each of these, as their own comparison pages.

Genesis Defense Thermique Blow Dry Primer vs Pureology Color Fanatic Multi-Tasking Leave-In Conditioner SprayPureology · 90% function matchExtreme Length Leave-In Conditioner vs No.6 Bond SmootherOlaplex · 93% function matchGenesis Defense Thermique Blow Dry Primer vs Bond Rx Leave-In TreatmentPaul Mitchell · 90% function matchExtreme Length Leave-In Conditioner vs ProVitamin Leave-In ConditionerAphogee · 90% function matchGenesis Defense Thermique Blow Dry Primer vs Blond Absolu Blonde Guard Hydrating Leave-In Conditioner Spray with Hyaluronic AcidKerastase · 88% function matchExtreme Length Leave-In Conditioner vs Strength Recovery Repairing & Strengthening SprayBiolage · 89% function matchGenesis Defense Thermique Blow Dry Primer vs Shea Pro Leave-in MoisturizerAphogee · 87% function matchExtreme Length Leave-In Conditioner vs Healthy Seal the Deal Split End Mender LotionSexy Hair · 88% function match

Genesis Defense Thermique Blow Dry Primer · Extreme Length Leave-In Conditioner · All heat protectants in the library

How this page was made

  • This page is assembled from the same researched records the individual product pages render: identity, each ingredient list as printed, each brand's own claims, dated price observations, and review themes written in our researchers' own words. Nothing on it is written per comparison.
  • We do not rank these against each other. Which of them suits you depends on your hair, and that is what the consultation works out.
  • The formula similarity percentage is a stored, precomputed number: position-weighted overlap of the two ingredient lists blended with agreement on the attributes we derive. It measures how alike two formulas are, not how well either works.
  • 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.
  • 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.
  • 7 sources were consulted across the products on this page.
  • Ingredient order tells you relative amount only above roughly 1%. Prices are observations on the dates shown and change without notice. We do not sell these products and take no placement fees.
  • This is cosmetic information, not medical advice, and nothing here diagnoses or treats a health condition.

Still unsure? Take your consultation or browse more products.

Your personalized hair plan

Tell us what’s going on with your hair, see what we understand, and get a plan built around it — with the reason behind every recommendation.

Free to start · $49.00 for your consultation and hair profile · No subscription · Nothing you must buy

Start your consultation