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Hairmetry

Encyclopedia

Every molecule that touches your hair

From proven medicines to kitchen-cupboard oils, with the studies behind each one.

16 entries

1

  • other

    18-MEA (18-methyleicosanoic acid)

    The fatty acid on the outer surface of virgin hair that makes it water-repellent and smooth, lost with weathering and chemical treatment.

A

  • chemical treatment

    Ammonia and monoethanolamine (MEA)

    The alkaline agents that swell the cuticle so dye and bleach can enter; "ammonia-free" MEA dyes are not gentler.

  • chemical treatment

    Ammonium thioglycolate

    The classic reducing agent in perms and thio relaxers; it breaks hair's disulfide bonds so the shape can change, with some loss each time.

  • silicone

    Amodimethicone

    A dimethicone with positively charged amine groups, so it clings to damaged hair and resists rinsing better than plain dimethicone.

B

  • bond builder

    Bis-aminopropyl diglycol dimaleate

    The active in Olaplex; it strengthens bleached hair in the lab, but the claim that it re-links broken disulfide bonds has never been independently confirmed.

  • silicone

    Bis-aminopropyl dimethicone

    An amino-terminated silicone related to amodimethicone, used in conditioners and colour-care products to stick to damaged hair.

C

  • other

    Ceramides

    Waxy lipids from the cement between hair cells; a lab study with ceramide-containing liposomes restored some lipids and break resistance, but retail products lack hair trials.

F

G

  • chemical treatment

    Glyoxylic acid

    Marketed as a safe "formaldehyde-free" straightening agent, but it has been linked to acute kidney failure and the EU has begun a safety review.

H

  • chemical treatment

    Hydrogen peroxide

    The oxidiser in every bleach and permanent dye; it lifts colour by destroying melanin but also oxidises the hair's own proteins, so damage rises with strength and repeat use.

  • protein or peptide

    Hydrolyzed keratin

    Keratin fragments, usually from wool or feathers, that coat damaged hair and in lab tests partly entered it and raised wet strength; the evidence is small and industry-linked.

  • protein or peptide

    Hydrolyzed wheat protein

    A common conditioner protein that raised dry strength of bleached and heat-damaged tresses in one lab test, with a small but real allergy risk.

K

  • bond builder

    K18 peptide (sh-Oligopeptide-78)

    A short cysteine-rich peptide modelled on hair keratin; inventor lab data look promising, but the one independent test found it acted mostly as a surface coating.

M

  • bond builder

    Maleic acid

    A small, cheap acid with a reactive double bond that is the working part of Olaplex-type bond builders; evidence that it repairs bleached hair comes from patents and spectroscopy, not controlled trials.

P

S