This is a guide to colour theory for hairdressing, including where natural hair gets its colour, and what depth and tone are. We also look at how colour theory is used to correct tones and the various factors that can cause hair to change colour. Understanding colour is an essential part of hairdressing – and this post covers all the basics you need to know.
Natural Hair Colour
Colour theory for hairdressing starts by understanding how natural hair gets its colour.
Natural hair colour depends on melanin pigments contained within the cortex of the hair.
There are two melanin pigments in human hair – eumelanin and pheomelanin. These pigments blend in varying amounts and proportions to form all the hair colours we see.
- Eumelanin provides black and brown pigments and, therefore, determines how dark hair is. Furthermore, when more of this pigment is present in someone’s hair, it gives the overall hair colour a cool look, like ash. Eumelanin pigments consist of all three primary colours – blue, red and yellow.
- Pheomelanin provides red and yellow pigments. It gives rise to warmer colours in someone’s hair, like auburn, strawberry or gold.
- Read about colour theory for makeup artists.
Why Natural Hair Changes Colour
We can change our hair colour by choice by using hair dyeing products. Here, the various chemical processes in hairdressing (like bleaching, tinting, neutralising) act on the natural pigments to change the hair’s colour.
However, hair colour can change for a variety of other reasons that are not always under our control, including:
- Ageing can affect pigment production. Consequently, as we age, melanin stops being made in our hair, and it grows without pigment. It’s why it is white. When white hair mixes with hair that still has colour, it creates a grey look – sometimes referred to as “salt and pepper”.
- Blonde children sometimes get darker hair when they are around seven or eight years old. They go on to have dark hair in adulthood. The hair darkens as melanin production increases.
- Environmental factors can also impact hair colour. For example, humidity and wind bring more oxygen to hair – and this attacks the pigments in the hair. Sunlight can then accelerate the process further. Blue pigments in the hair are the weakest and disappear first. It leaves the warm undertones of red and yellow showing through the hair. Our hair often lightens when on beach holidays due to being exposed more to the combination of sun and wind.
- Health issues can contribute to premature greying. For example, autoimmune thyroid disease, vitiligo, and ageing syndromes can lead to greying hair.
- Medication can alter natural hair colour. For example, certain drugs used to prevent malaria can lighten hair, while some epilepsy drugs can darken it.
- Pregnancy can darken light hair due to higher levels of hormones estrogen and progesterone.
Describing Hair Colour
The hair colour we see consists of depth and tone. Hair also has an undercoat, called undertone, which comes into play when we lighten or colour the hair.
Depth or Level
Depth or level simply refers to how light or dark the base colour of the hair is. There are 10 main levels talked about in hairdressing:
- Numbers 1-5 are brown shades – black, darkest brown, dark brown, medium brown, and light brown;
- Number 6-10 are blonde shades – dark blonde, medium blonde, light blonde, very light blonde, and lightest blonde.
- See the chart below for the hair colour numbering. All are classed as neutral shades.
Tone
Tone refers to the colours we see in the hair – be they natural colours or artificially added. Tonal colours are classed as warm, neutral or cool:
- Warm tones have reds, yellow and orange in them and are in colours such as strawberry blonde, copper and chestnut brown.
- Neutral tones have a balance of warm and cool pigments in them.
- Cool tones have blues and greens in them, referred to as ash tones.
The tonal quality of a hair tint is sometimes given as part of the colour’s description. For example, intense red, honey blonde, rich copper, light beige blonde, and deep chocolate are all descriptions that give us a clue as to what the finished colour will be.
There is also the ICC colouring system, with each tone given a specific number.
Undertones
Natural hair has an underlying warm tone, dictated by the amount of pigment pheomelanin found in the hair. Consequently, the undertone can affect the final colour result when dyeing hair.
Darker hair has more pheomelanin present as an undertone, which creates a red colour. Blondes have less, resulting in a more yellow undertone.
The undertone becomes more evident when hydrogen peroxide is used to lighten the hair. The undertone also shows through when hair is lightened naturally from exposure to the elements.
Pheomelanin is slowly oxidised during colouring and can produce those difficult-to-remove golden and orange tones in the hair. When dark hair is sufficiently bleached, it will go from having a red tinge to orange, then yellow and, finally, white as the pheomelanin breaks down.
