Understanding Hair

The key to great looking hair is to understand the structure of hair, the mechanisms by which hair is damaged and what you can do to minimise and reverse this damage. Think of your hair as being like an expensive, delicate item of clothing that needs careful handling in order to stay looking it’s best.

Structure of a hair follicle

Structure of a hair follicle

HAIR BIOLOGY

Your hair and nails are dead tissue, mainly made up of the protein keratin. Keratin protein also makes up rhinoceros horns, hedgehog spikes and pangolin scales.

The average number of hair follicles on a human head is 100,000, with a normal range of 50-150,000. Each follicle produces about 1cm of hair a month for a total of 1 kilometre of hair produced on the average head every month! Each hair has the same structure with a central medulla, a surrounding cortex covered by a scaly cuticle. 

Pristine baby hair. Note the perfect structure of the scales which make up the cuticle.

Pristine baby hair. Note the perfect structure of the scales which make up the cuticle.

CUTICLE

The outer cuticle layer is a layer of transparent keratin scales, ideally 7-10 scales thick. It’s main function is protection of the cortex. When the cuticle is healthy the scales are flat and smooth. Light reflects off the scales evenly and there is no friction when the hair rubs against other hairs, your comb or your fingers. It is silky and shiny.

CORTEX

The cortex makes up 80-90% of the hair’s mass. It is made up of spindle shaped cells filled with keratin protein and melanin. The structure of the cortex is what gives the hair it’s shape and colour.

Hair Colour

Melanin gives the hair it’s colour and comes in two types. Eumelanin is more common and is black. Whether the hair is light brown, dark brown or black hair depends on melanin concentration.

Phaeomelanin is less common. At low concentration it gives blonde hair it’s colour. At high concentration it is red or ginger.

Mild hair weathering. At this stage hair loses its shine.

Mild hair weathering. At this stage hair loses its shine.

Hair Waviness

The cross sectional shape of the hair shaft determines it’s natural degree of curl. A hair with a circular cross section is straight. This is typical of a lot of Asian hair. As the shape of the hair becomes more elliptical and flatter it is naturally more curly.

Kinky hair is the flattest and is most common in African hair. Wavy hair is more common in Caucasians and is in between.

 

MEDULLA

At the very centre of the hair shaft is a soft keratin containing medulla. Softer, thinner, blonder hairs may not have a medulla.

 

Moderate hair weathering. The rough edges rub against each other and cause frizzy hair.

Moderate hair weathering. The rough edges rub against each other and cause frizzy hair.

DAMAGED HAIR

Damaged or “weathered” hair has certain look. The amount of weathering our hair gets depends on your age and how much damage it is subjected to. Younger hair can take more stress. The more

  • Mild weathering. The scales of the cuticle become rough.The first visible sign is a loss of shine caused by scattered light reflecting off a damaged cuticle rather than off a smooth surface. Hair coatings like silicones and proteins fill the gaps and reflect light

 

  • Moderate weathering. The scales of the cuticle are very rough. The hair is harder to manage and tangles more easily as the rough edges no longer slide easily over each other. This friction causes an electrostatic charge to develop in the damaged cuticle causing frizzy, flyaway hair. If you have frizzy hair  you have at least moderate weathering.
Severe hair weathering with exposed and weathered cortex. This hair is likely to break.

Severe hair weathering with exposed and weathered cortex. This hair is likely to break.

 

  • Severe weathering. The cuticle is so severely damaged that patches of it have fallen off. The damage then extends to the underlying cortex. Visual effects are all of the above plus the hairs break. It can be hard to tell whether hair that falls out has broken or has fallen out as a result of a hair loss condition. You can tell a broken hair from a hair which falls out as a result of a medical condition by looking for a root (bulb). If you can see a white bulb at the base of the hair it is an intact hair and has fallen out, either naturally or as part of a hair loss condition. If you cannot see a bulb the hair has likely broken off.

 

 

Electron photomicrograph of a split end.

Electron photomicrograph of a split end.

Causes of Hair Damage

All hair accumulates some damage and weathering as it grows out. This is why our most damaged hair is our “split ends” and why short hair is usually of better quality than long hair. The following factors cause damage and weathering:

  • Genetics. Some people are born with weak, easily damaged hair shafts.
  • UV rays. Remember when you were a teenager and put some lemon juice in your hair and lay in the sun. The acid in the lemon juice cut through the cuticle and damaged the cortex.The UV rays further damaged the cortex and some melanin was able to be washed out. So you had lighter coloured hair but it felt rougher from the UV and acid damage.
Bubble hair caused by heating wet hair and creating bubbles of steam.

Bubble hair caused by heating wet hair and creating bubbles of steam.

  • Heat. Hair driers. Hair straighteners. Curling irons. Usually used on wet hair. Hair can swell by 20% when wet because of absorbed water. This water is boiled by hot hairdryers, heated straighteners and curlers causing bubbles of steam in the cortex and cuticle (bubble hair). The cuticle scales in this “bubble hair” can now easily flake off.
  • Chemicals. Especially chemical straightening, perming, dying and bleaching. Even when done expertly these procedures must cause damage to the cuticle layer in order to get to the cortex where they do their work. Hair dye which does not bleach the hair is less damaging.
  • Physical damage. Vigorous towel drying and using rough combs and brushes, especially on weaker wet hair. Do not brush your hair 100 times a day – this will weather it.

HAIR CARE TIPS

  1. Stop making things worse! Be gentle with your hair. Carefully towel dry it by pressing not rubbing.
  2. Do not comb wet hair. Water swells and weakens hair and it is more likely to suffer further damage or break.
  3. If you must use a comb use a wide toothed comb with teflon tips (but fingers are best).
  4. If you must use a brush use one with ball tips. A blow drying brush with vents is best. Natural bristles are the harshest to your hair.
  5. Try to let the hair dry naturally. If your hair is severely damaged you must avoid hair driers and heated curlers and straighteners.
  6. Choose the right shampoo (this is a website in itself). All shampoos are made of four elements; detergents, stabilisers, conditioning agents and additives to make them pleasant. It is the detergents which remove oil, dirt, dead skin cells and old hair product. Stabilisers ensure the shampoo does not break apart before you finish the bottle. Additives include lathering agents, foaming agents, perfumes, thickeners, pearlescents and opalescents.  And they contain conditioning agents. Conditioning agents coat the hairs and reduce static charge and friction, thereby reducing further breakage. They make the hair feel softer and silkier but also flatter.  If you have thin hair you may wish to choose a volumising shampoo which has fewer conditioning agents. Otherwise choose a shampoo for dry hair or conditioning shampoo (Pantene is the most famous). Both of these will contain more conditioning agents.
  7. Use a conditioner. These contain the same conditioning agents as conditioning shampoos but without the surfactants. Usual conditioning agents are silicones and methicones, fatty alcohols, cationic polymers and animal or wheat protein. Weathered hair is the growth industry in hair care and if you watch the ads closely they will push whichever of these agents they are currently promoting (currently the protein).
  8. There is a special conditioner for colour treated hair (SAPDMA) which replaces the water repelling fatty layer lost by the application of hair dye.
  9. Use a leave-on conditioner. Studies show that choosing a conditioning shampoo rather than a traditional shampoo reduces hair breakage by 75%. Adding in a conditioner reduces hair breakage by 97%. A “leave on” conditioner is even better. My opinion is that the best of these currently is Pantene Age Defy Advanced Thickening Treatment. It contains high doses of Panthenol, Caffeine and Niacinamide. You apply it to clean hair at the roots in order to get lift and began the coating process. After about 20 applications the hair shafts are 50% thicker and the hair looks more full and youthful.
  10. Consider a weekly deep conditioning treatment. If your hair has been chemically straightened use an oil based one, otherwise a protein based will leave the hair less limp and will be more manageable.
  11. Trim your split ends so that they don’t split further up the hair. Go as short as you can stand.
  12. Think of your hair as being like an expensive, delicate item of clothing that needs careful handling in order to stay looking it’s best.