The Science Library

Editorial explainers on hair structure, bleach damage, click chemistry, tensile testing, and molecular reconstruction. Written to clarify the mechanism before the claim.

Hair concerns

Treatment guides by damage pattern.

Choose the damage pattern you recognize, then move between the treatment and its mechanism. If the pattern is mixed, take the 60-second consultation. When you are ready for the full protocol, view the Complete Reconstruction System.

Bleach damage

For hair that feels gummy, porous, or structurally weakened after lightening. View treatment Read the science

Heat damage

For repeated blow-drying or hot-tool stress showing up as brittleness and breakage. View treatment Read the science

Split ends & breakage

For fraying, snapping, and weak points that keep travelling up the fibre. View treatment Read the science

Find your protocol

Use the 60-second consultation when damage is mixed or the right starting point is unclear. Start consultation

Featured · Start here

Hair Porosity: What It Is, How to Test It, and High vs Low Porosity Hair

Hair porosity is how easily water and products move into and out of a hair strand. How to test yours with a spray bottle and your own roots, why the float test misleads, and what high vs low porosity means for damage.

Read the guide

All articles

A glossy lock beside lab glass and a serum drop, molecular hair repair.

April 25, 2026

What Is Molecular Hair Repair?

Molecular hair repair explained with mechanism-first language and internal links to ANATOMY's science and complete protocol.

A single hair fibre seamlessly mended, hair bond repair.

April 18, 2026

Hair Bond Repair Guide: What Bonds Matter and What Repair Can Mean

A precise guide to hair bonds, disulfide bridges, and how bond repair differs from ANATOMY molecular reconstruction.

A single hair fibre catching a precise point of light, click chemistry for haircare.

April 11, 2026

Click Chemistry for Haircare, Explained

A plain-English explanation of click chemistry in haircare and how ANATOMY connects the logic to molecular reconstruction.

A hair fibre clamped and stretched for measurement, hair tensile testing.

March 7, 2026

What Is Tensile Testing for Hair?

Tensile testing for hair explained: what is measured, why cross-sectional area matters, and how to interpret pre/post fiber data.

A hair fibre split to show cuticle and cortex, cuticle versus cortex damage.

February 28, 2026

Cuticle vs Cortex Hair Damage

Cuticle vs cortex damage explained: what each layer does, why coatings are limited, and how ANATOMY connects the problem to molecular reconstruction.

Glossy platinum blonde waves, a bleached hair repair guide.

February 21, 2026

Bleached Hair Repair: What Actually Works

A structural guide to bleached hair repair, gummy hair, oxidative damage, and ANATOMY's bundle-first reconstruction protocol.

A limp wet over-processed blonde lock, gummy bleached hair.

February 14, 2026

Why Bleached Hair Feels Gummy

Why bleached hair feels gummy, what it suggests structurally, what to avoid, and how ANATOMY explains the problem through reconstruction.

A lock mid-snap with broken strands near a comb, hair breakage when brushing.

January 24, 2026

Why Damaged Hair Breaks When Brushed

Why damaged hair breaks during brushing, how cuticle abrasion and cortex weakness interact, and how ANATOMY explains breakage through reconstruction.

A scorched hair tip near a warm glow, heat damaged hair structure.

January 17, 2026

Heat Damaged Hair: Surface Feel vs Structure

Heat damaged hair explained as cumulative structural stress, surface behavior, cortex resilience, and Leave-In's role.

A hair lock submerged in cloudy hard water with mineral bubbles, hard water and hair.

May 28, 2026

Hard Water and Hair: Why Minerals Stiffen Your Strands

Hard-water minerals like calcium, copper, and iron build up in hair, stiffen it, and dull color, especially in porous hair. Chelating shampoos clear them.

A glossy twisted rope of hair like a protein cable, keratin.

May 28, 2026

Keratin: The Protein Your Hair Is Made Of

Keratin is the structural protein that makes up hair. Understanding it explains why 'keratin treatments' coat rather than rebuild, and what real repair requires.

A waterlogged limp swollen lock, hygral fatigue.

May 28, 2026

Hygral Fatigue: Why Damaged Hair Gets Worse Every Wash

Hygral fatigue is the slow wear from hair swelling when wet and shrinking when dry. Damaged hair suffers it badly because it lost its lubricating coating.

A single hair fibre with internal crosslinks glinting within, disulfide bonds.

May 28, 2026

Disulfide Bonds: The Cross-Links That Make Hair Strong

Disulfide bonds are the sulfur cross-links that hold the hair cortex together. Bleach breaks them; rebuilding them is what restores strength.

A frayed fibre revealing inner fibrils, the hair cortex.

May 28, 2026

The Hair Cortex: Where Your Hair's Strength Lives

The cortex is the strand's core, a cable of twisted protein held by disulfide bonds. It decides how strong your hair is and what snaps when it breaks.

Macro of overlapping cuticle scales on a hair fibre, the hair cuticle.

May 28, 2026

The Hair Cuticle: The Scale Layer That Protects the Strand

The cuticle is the layer of overlapping scales, like roof tiles, that armors the hair strand. When it lifts, hair turns rough, dull, and porous.

Three hair locks compared on marble, three bond-repair mechanisms.

May 28, 2026

ANATOMY vs Olaplex vs K18: How They Differ

Three bond-repair systems, three different chemistries. Click-chemistry covalent crosslinking, single-bond bis-aminoethanethiosulfonate, and oligopeptide repair — compared on mechanism, peer-reviewed data, and outcomes. By ANATOMY.

Water soaking into a bleached blonde lock, bleached hair and high porosity.

May 28, 2026

Is Bleached Hair Always High Porosity?

Yes — almost always. The science of how bleach changes the hair cuticle and cortex, the timeline, and what restores porosity. Peer-reviewed answer. By ANATOMY.

Water soaked into a dull saturated damaged lock, high porosity hair.

May 28, 2026

High Porosity Hair: What It Is and What Fixes It

High porosity hair is structurally damaged hair: 18-MEA-stripped surface and disulfide-broken cortex. The peer-reviewed causes, the Class 1/2/3 repair taxonomy, and what actually works. By ANATOMY.

Water beading and rolling off glossy sealed hair, low porosity hair.

May 28, 2026

Low Porosity Hair: The Real Science

Low porosity hair is structurally low-porosity virgin or near-virgin hair. What actually penetrates it (and what does not), how to test it, and the truth about "low porosity hair products." By ANATOMY.

A product droplet wrapping a single frayed fibre, do bond builders work.

March 14, 2026

Do Bond Builders Actually Work? What the Chemistry Says.

A chemistry-first guide to bond-builder claims, surface improvement, molecular reconstruction, and measured proof.

A dry lock with a lather bubble and droplet, best shampoo for dry hair.

February 28, 2026

How to Choose the Best Shampoo for Extremely Dry Hair

Library Dry hair is not always a moisture problem. A mechanism-first guide to choosing shampoo when hair feels dry, brittle, porous, or structurally weakened. Published February 28, 2026 Updated April 26, 2026 Science Library Contents AnswerDryness vs damageShampoo roleAvoidSelection frameRoutineStructureProtocolReferences...