Updated January 2023 By Dr Jonathan Palmer

How Hair Colouring and Perming Works

First, a little hair chemistry!

Hair comprises 65-95% protein, consisting of primarily cysteine-rich keratin fibres found in both the cortex and cuticle. Keratin is rich in the amino acid cysteine. Cysteine contains a sulphur atom on its side chain responsible for making disulphide bonds (bridges) with other cysteines. These disulphide bonds make hair strong and resilient to most daily hair routines, such as heating, brushing and washing. 

Another essential type of chemical bond in hair is the hydrogen bond. These are easily broken by water but are naturally reformed without chemicals. Hydrogen bonding is relatively weak compared to disulphide bonds but is much more numerous.

What Curling and Perming does to your hair

Many curling and perming treatments use chemicals such as thioglycolate that easily break disulphide bonds. This breaking and subsequent reforming of these bonds reorganise both the molecular and macrostructure of your hair, resulting in your hair being permanently restyled.

Using thioglycolates has been shown to cause a lot of damage to your hair, leading to increased porosity, breakage, mid fibre splitting and frizz. Often a weak peroxide mix is used to neutralise the activity of the thioglycolate, which not only causes hair damage by itself and lightens your hair colour.

What permanent hair dyes do to your hair

Peroxides remove the colour (pigment) from your hair. The peroxides interact with the colour granules found within the cortex but have off-target effects (side effects) that disturb both the cortex and cuticle of your hair.

Peroxide-containing products are highly oxidative and so cause massive free radical damage to your hair.

Damage caused by perm, curling and permanent dye products on your hair is accumulative and permanent.

Are you worried about your hair? Maybe because it is regularly dyed or straightened, don’t worry, we can help. Think you have high porosity, split ends or frizz. Get the look you want and reduce the damage to your hair using our complete hair health and beauty analysis.

If you have any questions about your hair or hair testing then please feel free to contact us and we’d be happy to help.