The use of colour to enhance the appearance of hair has been used by people for centuries. Closely influenced by developments in chemistry and cosmetic manufacturing, the range of hair colours and products available today is huge. But before we colour our hair, we need to understand basic colour theory for hair. Here we look at how natural hair gets its colour, what depth and tone mean, and how we use colour theory to correct tones.
Basic Colour Theory for Hairdressing
All colours found in nature are a mix of the three primary colours: blue, red and yellow. These three pigments produce every known colour in the world.
When mixed in equal quantity, the primary colours give us a neutral brown. Our skin, eye and hair colour is made up of various combinations of blue, red and yellow colour molecules.
Blue is the only cool primary colour – red and yellow are warm.
Pigments that colour our hair are found in the cortex
Primary colours vary in molecular size and pigment weight – and this is important to understand in hair colouring. Blue has the largest molecular size and pigment weight, followed by red and then yellow.
In the hair shaft, blue molecules (being the biggest) sit closest to the cuticle and is the easiest pigment to remove. Red is found deeper in the cortex and is harder to remove than blue. Harder still is yellow, which sits deepest in the cortex. It is why red and yellow are harder colours to remove during the lightening process.
To remove red and yellow, the hair shaft needs to be expanded large enough and for long enough during colouring to allow oxidation to dissipate the molecules into the air.
- More on colour theory
Natural Hair Colour
Our natural hair colour depends on melanin pigments within the cortex of the hair.
There are two main pigments found in human hair, and they blend together in various amounts and proportions to form all the hair colours:
- Eumelanin provides black and brown colours and determines how dark hair is. More of this pigment gives the overall hair colour a “cool” look, like ash. Eumelanin consists of all the three primary colours: blue, red and yellow.
- Pheomelanin provides red and yellow colours. This pigment gives rise to “warm” colours in hair, like auburn, strawberry or gold.
Brown hair contains a lot of eumelanin, red hair has large quantities of pheomelanin, while light blonde hair actually contains relatively little melanin (the pale yellow we see is actually due to keratin, rather than pigments). White and albino hair contains little or no pigment at all.
Why Hair Colour Changes
Hair colour can change for a variety of natural reasons, as well as by using hair colouring products.
- Blonde hair in childhood can change into dark hair in adulthood. It darkens as melanin production increases.
- Ageing can affect pigment production. As we age, melanin stops being made in our hair and new hairs grow without pigment, which is why they are white. When white hair is mixed with hair that still has colour, it creates a grey look (sometimes called “salt and pepper”).
- Health issues (like stress) can also have an impact on our pigment production, causing melanin to cease.
- Environmental factors can impact hair colour. Oxygen in the air attacks the pigments in hair. Blue pigments are the weakest pigments and are, therefore, the first to disappear, leaving hair with the warm undertones showing through. Humidity and wind brings more oxygen to hair, and sunlight accelerates the process. Hence why our hair often lightens noticeably when on beach holidays.
- Various chemical processes in hairdressing – bleaching, tinting, neutralising – act on the natural pigments to change the hair’s colour.
Describing Hair Colour
The hair colour we see consists of depth and tone. Hair also has an undercoat of colour, called undertones, which only come into play when we lighten or colour the hair.
Depth
Depth refers to how light or dark the base colour of the hair is. It is sometimes called level, with dark hair having a low level and light hair having a high level. In hairdressing terms, there are 10 depths: black, darkest brown, dark brown, medium brown, light brown, dark blonde, medium blonde, light blonde and lightest blonde. All are neutral shades.
Tone
Tone refers to the colours we see in the hair and 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, and are often referred to as ash tones.
For hair colouring products, the tonal quality of the finished result is often given as part of the colour’s description (e.g. intense red, honey blonde, rich copper, light beige blonde, deep chocolate).
Undertones
The underlying warm pigment that all natural hair colours have, from red for darker hair and yellow for lighter hair. ICC is the International Colour Chart system
Natural hair has an underlying warm tone, dictated by the amount of the pigment pheomelanin found in the hair. Dark hair has more pheomelanin, creating a red undertone; blondes have less, resulting in a yellow undertone.
The undertone becomes more evident when hydrogen peroxide is used to lighten the hair. It also shows through when hair is naturally lightened 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. Undertone can affect the final colour result when dyeing hair. When dark hair is bleached sufficiently, it will go from having a red tinge to orange, yellow and, finally, white as the pheomelanin breaks down.
Correcting or Neutralising Unwanted Tones
The colour wheel – essential to know and understand when working in hairdressing or makeup
Correcting tones in hair needs an understanding of colour theory, as well as knowing what products to use and application techniques.
To neutralise an unwanted tone, the opposite colour on the colour wheel is used.
So, to remove a gold brassy look from blonde hair, we use a purple shampoo or a mauve ash toner to knock out the unwanted yellow. If the brassiness is more orange, then a blue-based product would be used. If hair has a green cast to it (sometimes caused by dyeing hair with an ash colour), a red-based product is used (yes, tomato ketchup!).
The colours opposite each other on the colour wheel are also opposite in terms of tone – that is, warm colours neutralise cool colours, and vice versa. For example, red (warm) and its opposite colour green (cool) neutralise each other.
Completely neutralising the effect of a tone achieves a neutral brown shade that is neither warm nor cool.
What Media Hair and Makeup Artists Should Know
When we look at hair, the colour we see is influenced by several factors:
- The pigments (both natural and artificial) in the hair, which absorb some light and reflect others;
- The brightness and colour of the light in which we are looking at the hair;
- To some extent, the clothing worn by the person, or the environment they are in.
So, as well as knowing your colour theory, you should also consider other aspects of working in film, TV or theatre. Understand how lighting affects colour, how the colour and material used for costumes and sets can reflect onto hair and skin, and how different hair (from natural to wigs made from various types of hair) can look on camera or stage.
Find Out More:
Sources:
Lloyd, T & McMillan-Bodell, C. 2005. The Colour Book: The Official Guide to Colour for NVQ Levels 2 & 3. Cengage Learning Vocational. 260pp.
Palladino, L. & Green, M. 2006. Hairdressing: The Foundations. 5th Edition. Thomson. 416pp.
