Mixed Hair Types & Straight Hair | Curly Hair

Over many thousands of years these three groups of people have intermingled. Their descendants now show every imaginable blend of hair type and color.

Of the three racial groups, the Caucasoids are by far the most varied in the appearance of their hair. It may fall completely straight, it may be crinkly or wavy, or it may form large curls, or pretty well anything in between. Blondes tend to have straight hair, while more brunettes have curly hair. The longer the hair grows, the more obvious its basic character becomes. The first month or two's growth of a new hair may be straight, but then it may start to curl or wave.

Types of Hair Variations

Scientists do not fully understand why the different types of hair growth have Straight Hair, Curly Hair, Wavy Hair, Greasy Hair or Dry Hair. This is probably determined by several factors, which may vary in their importance during life. This is why some curly-headed children have straight hair later in life, and vice versa. These factors include:

• The way the large bundles of keratin are arranged within each hair shaft

• The position of the hair bulb in the hair follicle - in African hair the bulb may lie to the side of the follicle, and so the hair shaft grows out of the follicle at an acute angle

• Irregular growth in the hair bulb - if it varies slightly to one side or the other the hair may grow wavy

• The shape of the hair follicle, whether it is straight or curved

• The number of twists per unit length

All hair, even the apparently perfectly straight hair of Asian people, twists as it grows. The number of twists in a given length of hair determine how curly it is: the more twists there are, the curlier it will be. Some African hair has 12 times as many twists per centimetre as Caucasian hair.
In Asian people the keratin bundles in the hair are all straight. The hair shaft tends to be thick, and almost completely round.

The keratin bundles in the hair of Caucasoid people are a mixture: most are straight, some are wavy. The proportions of the two types vary a lot. The hair shaft is usually oval in shape.

The tightly curled hair of African people twists much more frequently than in the other groups. The hair shafts are markedly oval in shape, with definite edges. The cuticle is sharply kinked at the edges, and is especially easily damaged at these points. This curious shape is the reason for the vulnerability of African hair to all forms of physical and chemical trauma, and its consequent need for extreme care in handling and very thorough conditioning.

Straight hair sometimes becomes quite wavy when damp, and wavy hair may become straight when thoroughly doused with water - in a swimming pool, for instance. This is because in these conditions great numbers of hydrogen bonds have been broken. The effect is very temporary, and the hair recovers on drying

Asian Hair & Caucasoid Hair & African Hair

Asian Hair people are from the Orient, for example from China and Japan. Their hair is very straight, and always black in color.

The Caucasoid group is the most 'varied' of the three racial groups. Modern Caucasoids are very varied, even though they are descended from the same group of ancestors. They range from the fair-skinned people of north-west Europe to the widely varying peoples of the Indian subcontinent.

Caucasoid Hair may be either wavy or straight, and the diameter varies widely too. The color ranges from black to a pale blond that is almost white, including just about every possible shade in between.

African people originated in Africa. African hair is black and tightly curled. It tends to be woolly and dry, and is extremely easily damaged by heat or chemicals.

Different Types of Hair

The range of different types of hair is enormous, ranging from tight wiry curls to ruler-straight. The color and shape of hair vary too. What accounts for these differences?

The type of hair you have is inherited from your parents. We may look back further, and say that it is determined by the part of the world in which your ancestors originated. It all depends on the race, or mixture of races, from which they came.

In the very earliest days of human evolution, three basic racial groups of people seem to have existed on this planet. These spread out across the world and became mixed together. They are especially well mixed in countries where there has been massive immigration, such as the U.S.A. over the last few hundred years.

Scientists have identified three basic types of hair in today's human population, and have related them to these three early races: Asian, Caucasoid and African. The three types of hair not only look quite different, but the differences in their responses to physical and chemical damage can be remarkable.

Hair Texture

Much of the attraction of a beautiful head of hair lies in its texture, or feel. The texture of hair depends on several things.

The first is the average diameter of the individual hairs. We have seen that these vary widely. The larger the hair diameter, the coarser it will feel.

Secondly, different people's hair naturally feels different: some hard and others soft, some silky and others wiry. The reasons underlying these differences are still a matter for scientists to argue over.Thirdly, the texture is affected by the degree of weathering of the hair.

Finally, hair texture is affected by what has been put on it. Repeated lavish applications of hair spray gives hair a different feel from that of hair that has been freshly washed and conditioned. Conditioners make hair feel soft and smooth. Conditioners that contain silicones even give a slightly different feel from those that don't (most manufacturers do put silicones into conditioners nowadays, however, as they protect the hair cuticle). Contrary to popular belief, this altered feel is not a sign of build-up.

Hair Diameter & Hair Porosity

The elastic properties of both wet and dry hair are related to the diameter of the hair shaft. The thicker the hair, the more it will tend to resist stretching

In a normal, undamaged hair shaft, very little water can get either into or out of the cortex. This is because the cuticle covering the cortex is intact, and is then almost (but not quite) waterproof. Shampoos do not damage the cuticle. When hair is permed or tinted, however, the chemicals have to penetrate the cortex in order to react with the keratin inside it. Increasing the temperature, or applying an alkaline lotion, separates the scales of the cuticle enough to allow the chemicals to pass through. After the processing is finished the scales gradually close up again.

But if hair is processed too many times the cuticle scales may never return to their original tightness and the protection they once offered is lost. The cuticle can also be damaged in the same way by too much blow drying, curling irons that are too hot, and the effects of wind and sun. The hair becomes increasingly porous, and water can then pass in and out of the cortex.

Over-porous hair is dry, and tends to develop split ends. The damaged cuticle is fragile, and the damage worsens as time goes by. The greater the damage, the more the cortex swells with water whenever the hair is washed, but the more water it loses when it dries. The repeated wetting and drying of the cortex gradually weakens the hair.

Hair Moisture

The moisture content of hair is greater when the atmosphere is moist and humid, and less when the air is dry.

The reason why hair 'collapses' in hot, humid atmospheres is summed up by:
heat and humidity -> more moisture
-> less static electricity
-> collapse
In dry conditions:
heat and dryness -> less moisture
-> more static electricity
-> more volume (body)

When hair is wet the cortex swells and the edges of the cuticle scales tend to lift. The hair surface temporarily loses its smoothness.There is therefore more friction when wet hair is rubbed than when it is dry. This is what can lead to matting and tangles developing during over-vigorous shampooing (there is not greater static charge on wet hair than on dry).

These tangles are one of the reasons why many children hate having their hair washed, and the problem is easy to avoid.

Hair Static Electricity

When dry hair is rubbed, as it is whenever it is brushed or combed, static electric charge builds up on the hairs. This is especially noticeable in hot, dry weather. The charges tend to push each other apart, and as a result charged hairs can never lie smoothly against each other. The result is 'fly away' hair, which stands out from the head and looks unmanageable.

Conditioners, and shampoos with high levels of conditioning agents in them, leave the surfaces of the hair smooth. There is therefore less friction when the hairs are rubbed: hence less static electricity builds up on them, and 'fly away' is reduced

Hair Elasticity

This is one of the most important properties of hair. Because of its elasticity, hair can resist forces that could change its shape, its volume or its length. Its elasticity lets it spring back to its original form without damage.

When healthy hair is wetted and stretched, it can increase in length by up to 30% and still return to its original length when it is dried. Stretching it more than this will tend to damage it, however, leading to permanent lengthening and even breaking.

The elasticity of hair depends on the long keratin fibres in the cortex. Chemical treatments of hair such as perming and bleaching can alter the cortex after repeated damage, and change the hair's elasticity. Hair with poor elasticity will stretch only to a limited extent. It will not curl, it will break easily when it is groomed and it cannot be permed satisfactorily.Both natural sunlight and artificial ultraviolet light break down chemicals in the hair and damage its elasticity in the same way that bleaching does, though to a much lesser degree.

A stylist must always examine the elasticity of a client's hair before deciding on any chemical procedure.

Physical Properties of Hair

Hair can be stretched, bent and curled. It can absorb moisture or lose it. Its behaviour can alter when it is wetted or when it is brushed. We look at the special properties of hair, such as its elasticity, porosity and texture.

Understanding these properties is important for all of us as we cope with our hair under different circumstances. It is especially important for the hair stylist who has to decide on styles and to suggest continuing hair care regimes for clients.