The World of Hair by John Gray

The World of Hair Colour (Hairdressing and Beauty Industry Authority)

online version

Hair is an indicator of health, a large part of a woman’s identity, and has played a large part in many famous stories (Samson, Rapunzel ...). Knowing the importance of hair is only a small part of the puzzle. It is important to know how hair works, what the signs of healthy hair are, how to care for your hair, and what dangers to avoid.

While researching hair I came across a good resource: an e-book called The World of Hair by Dr. John Gray. This book represents conventional science, so it must be read with a grain of salt. Its intended audience seems to be hair stylists, so it covers both the theory behind hair and how to care for it. I will summarize what I feel are the most important points of this book.

Hair Structure:
The two parts of a hair are the follicle which is below the surface of the skin where hair grows and the shaft which is outside of the skin. New cells are created in the follicle and pushed outwards to become the shaft. Hair pigment is created in the follicle. The shaft is composed of dead cells and lubricated by sebum which is secreted from the follicle. The center of the shaft is called the cortex and gives hair its curl and elasticity. It is made up of keratin and contains the in hairpigments. The outside of the shaft is called the cuticle is composed of between six and ten layers of cells and takes the form of a layer of scales covering the cortex. The cuticle gives hair its shine.

Hair Statistics:
People generally have between 100,000 and 150,000 hairs on their head. The number of hairs generally peaks around the age of 16 years old while the density of hair decreases throughout life. A baby will have around 1,100 hairs/cm2; a 25 year old, 600 hair/cm2, and someone 40 or older 300 hair/cm2. Hair usually grows at the rate of 1cm/month. Consequently shoulder length hair has usually been growing for 3 years and waist length hair for 7 years.

Hair Life Cycle:
Hair has three stages to its lifecycle. Anagen is the first phase in which the hair grows; this stage usually lasts between three and seven years. Catagen is the second phase lasting two to four weeks. During this phase hair stops growing and becomes ready for shedding. Telogen is the third phase; here a new hair starts to grow and the old hair falls out. This final stage lasts three to four months.

Hair Types:
Asian is the first of the hair categories based upon genetics. Asian hair is black and very straight. The straightness is due to the straightness of the keratin bundles. The shaft of the hair is round and thick. Its diameter can be more than 120 microns.

Caucasoid is the second type of hair. It is possessed by Europeans and Indians. It can be wavy or straight and has a wide range of colors. A mix of straight and wavy keratin bundles is found in the hair. The shaft is usually between 57 and 90 microns in diameter and oval in cross section.

The third type of hair is African. African hair is black and very curly. It is flatter in shape and the cuticle has many kinks in it.

In healthy hair the cortex or central part of the hair shaft is undamaged and the cuticle or covering sheath of the shaft is intact. Keeping hair in this state is easier said than done because once hair leaves the scalp it cannot be repaired. Hair needs to maintain its pristine conditions for a long time: 3 years for shoulder length, 5 years for waist length, and 12 years for hair long enough to sit on.

Since not everyone owns a high power microscope to examine their hair for damage, it is important to be able to tell hair’s healthiness through observation with the naked eyeball. Here the useful correlation between health and beauty aids us because we can recognize healthy hair instinctively. This explains why men are attracted to hair even though most men know almost nothing about hair. Properties of healthy and beautiful hair include glossiness, cleanness, amount, and volume.

The glossier hair is the more light it reflects. This is the most obvious property of healthy hair. Dark hair is generally glossier than light hair (this does not mean dark hair is better) because of the contrast between the shine and the natural hair color. Hair’s glossiness depends on the state of the cuticle. If the cuticle is mostly gone or highly damaged, hair will not reflect much light.

Clean hair is free of debris and has a proper level of natural oils. Hair naturally produces oil and should have some; however, it should not be excessively oily. There should not be debris or caked hairspray in the hair. Dirty hair is not as glossy as clean hair.

The amount of hair depends on the diameter of the hair shaft and number of hairs. The diameter of a pony tail can vary by more than 100% based upon the diameter and number of hairs. Both number of hairs and diameter of hair shaft are related to genetics and healthiness of lifestyle. Even though modern science says that both of these are fully genetic, it admits that in the case of starvation or high stress hair is lost and changes color. The amount of hair varies with length as well, but most of the time people do not grow their hair to its limiting length.

Volume is amount of space hair takes up. It is dependent on “thickness” as described in the previous paragraph but not entirely so. Hair properties such as stiffness, curvature, cohesion, and friction play a large role in determining hair’s volume. These cause hair to flow and hold itself in ways that hold more air inside and make it look bigger. While the amount of hair depends on ones long term health (of yourself and your ancestor), volume can be vary from day to day based upon treatment and weather conditions.

Next I will discuss general Dr. Gray's ideas about hair care and not specific techniques. First I will discuss styling and then cleaning. Hair styling is temporarily or permanently altering the shape of hair. Temporarily changing the shape of hair involves setting and changes weak bonds between hair while permanent altering either “perming” or “relaxing” chemically changes the shape of hair. Cleaning hair involves both the method of cleaning hair as well as the materials used.

Setting or temporary styling involves drying hair into place. This needs to be done every time hair is wetted. This is the safest way to style hair and everyone does it without thinking. Having a good haircut can make this easier. Avoid is back combing. This can increase the friction of hair leading to more volume, but it pushes up scales on the cuticle damaging the hair. Be careful about blow drying hair. Everyone agrees that air drying is optimal, but this takes a long time. Heat damages hair, and if there is a lot of water remaining in hair when it is blow dried, the water on the hair can boil seriously damaging the hair. For this reason towel dry and air dry as much as possible before blow drying. Hair can also be temporarily colored; this colors the hair with pigments which will eventually wash out. I would guess that this is not healthy [but more healthy than permanent coloring] because the pigments will also be absorbed into the scalp.

Permanent styling of hair changes the structure of hair through chemical processes. Usually a chemical is applied to the scalp which alters the structure of the hair chemically and a physical force is used to reshape the hair either curling (perm) or straitening (relaxing). After a period of time a neutralizing agent is applied counteracts the original chemical and locks the hair into its new form. Hair may be permanently colored as well. Here the pigments in the hair are neutralized and permanent dyes are used to change the color of the hair. Conducting these chemical causes permanent damage to hair and the author repeatedly emphasizes the need to determine what treatments hair has already received before applying new treatments so that hair is not too heavily damaged. There are many pictures in the book captioned by a statement along the lines of “this extremely beautiful hair has never been touched by any chemical treatment.”

A shampoo and possibly a conditioner is used to clean and care for hair on a regular basis. It is important to know your hair type in order to pick the correct shampoo. A shampoo removes grease and dirt from hair while a conditioner prevents tangling and protects the cuticle. Dr. Gray says that hair is washed much more often now than it had been in the past because shampoos are not as harsh as they used to be. I infer that you do not need to wash your hair nearly as much as we do.

Let your hair hang naturally and not pile it on top of your head while washing. Piling the hair will causing tangling and other problems. Do not scrub the hair too vigorously either. Shampoo should be applied mainly to the scalp while conditioner needs to be spread evenly throughout the hair