Hair Chemistry

Keratin

The fibrous protein that makes up approximately 85% to 90% of hair's total dry weight.

Cysteine

An amino acid rich in sulfur, essential for forming disulfide bonds in hair.

Cuticle

The outermost protective layer of hair consisting of overlapping, scale-like cells.

Cortex

The thick middle layer of hair containing keratin bundles and hair pigment, contributing to elasticity and tensile strength.

Medulla

The innermost core of hair, made of soft keratin and air spaces, often absent in fine hair types.

Disulfide Bonds

Strong covalent bonds formed between sulfur atoms of two cysteine residues, representing approximately 1/3 of total hair strength.

Hydrogen Bonds

Weak physical bonds formed by electrostatic attraction between hydrogen and electronegative atoms, accounting for 1/3 of hair's physical strength.

Salt Bridges

Ionic bonds formed by attractions between charged amino acids, sensitive to pH changes.

pH of Hair

Natural pH of hair ranges from 4.5 to 5.5, affecting hair's cuticle condition.

Permanent Waving

A hair chemical process that involves reduction of disulfide bonds followed by reshaping.

Bleaching

A process where alkaline agents open the cuticle to allow hydrogen peroxide to oxidize melanin.

Permanent Dyeing

A method that allows dye precursors to enter the cortex and polymerize into colored pigment molecules.