The effects of different colouring

products on the hair

• You will be looking at the effects of the following

colouring products on the hair:

• Temporary colour

• Semi-permanent colour

• Quasi-permanent colour

• Permanent colour

• Bleach.

The effects of temporary colour

Large colour

molecules coat the

hair cuticle.

There is no

penetration of the hair

cortex.

The colour will last for

only 1 or 2 washes.

The effects of semi-permanent colour

Small colour molecules are deposited into the hair cuticle and the outer edge of the hair cortex.

The colour will last for between 6 to 8 washes.

If the hair is unevenly porous, the result may be patchy.

The effects of quasi-permanent

colour

The quasi-permanent colour is mixed with a low-volume oxidant (1:2 ratio).

Different sized colour molecules enter the cortex and are oxidized by the oxidant.

Because the oxidant is mild, the colour molecules do not become very large and are gradually lost each time the hair is shampooed.

The colour is designed to fade over a period of 12 weeks.

The effects of permanent colour –

stage 1 The permanent colour

is mixed with hydrogen peroxide.

The strength of hydrogen peroxide used varies depending on the desired result (10, 20, 30 or 40 volume).

When mixed with hydrogen peroxide, the small colourless molecules penetrate the hair cuticle and the hair cortex.

small

colourless

molecules

mixed with

oxidant

penetrate

the cuticle,

into the

cortex

The effects of permanent colour –

stage 2 The hydrogen peroxide

begins to break down into water and oxygen.

The oxygen from the hydrogen peroxide joins together with and oxidises the small colourless molecules.

The oxidised molecules swell to form large, colour molecules.

The large colour molecules are unable to pass back through the hair cuticle and become trapped within the hair cortex.

small

colourles

s

molecule

s mixed

with

oxidant

penetrate

the

cuticle, in

to the

cortexsmall

molecule

s swell

and

become

larger

due to

the

nascent

oxygen

The hair before bleaching

Bleaching is the process of

changing the natural colour

pigments in the hair

so they become colourless.

The natural hair pigments are

melanin and pheomelanin.

• Melanin pigments are black and

brown.

• Pheomelanin pigments are red

and yellow.

Natural colour pigment.

Hair prior to bleach

application

The hair after bleaching

The bleach penetrates

the hair cortex and

oxidises

the natural colour

pigment so that it

becomes colourless.

For example, brown

melanin pigments are

changed to colourless

oxymelanin.

Colourless,

oxymelanin

Hair after bleaching