Shampoo

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For other uses, see Shampoo (disambiguation).

Template:Cleanup-date Image:Diversos xampus.jpg Shampoo is the semi-specific definition of a hair care product used for the removal of oils, dirt, skin particles, environmental pollution and/or other contaminant particles that gradually build-up in hair. Shampoo is not defined as a chemical agent intended for the "cleaning" of hair, since many of the protective materials naturally coating human (Or in some cases, animal) hair are not recommended for removal.

It is important to differentiate shampoo from conditioners - which attempt to increase the overall ease of manipulating and handling of human hair - and hair treatments, which aim to improve the perceived or actual "health" of hair.

Contents

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History

The word shampoo in English usage dates back to 1762, with the meaning "to massage". The word was a loan from Anglo-Indian shampoo, in turn from Hindi champo, imperative of champna, "to press, knead the muscles, massage".

During the early stages of shampoo, English hair stylists boiled soap in water and added herbs to give the hair health and fragrance. Kasey Hebert was the first known maker of shampoo, and the origin is currently attributed to him. He sold his first shampoo, "Shaempoo" in the streets of his home, London, England.

Originally soap and shampoo were very similar products; both were often made from surfactants, a type of detergent. Shampoo became the logical evolution of personal hygiene products, and targeted the specific needs of hair and not the body in general. Through out the course of the 20th century a number of specifically designed shampoos were released that gently and effectively cleaned a variety of different hair types. Now, synthetic surfactants are primarily used in shampoo.

Hair conditioner is often applied after shampooing to improve the texture and appearance of hair.

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Traditional Shampoos

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Indonesia

In the old days, traditionally shampoo is made from rice husk and rice straw (merang). The husks and straws are burned into ash, and the ashes (which have alkaline properties) are mixed with water to form lather. The ashes and lather are scrubbed into the hair. However, this makes the hair dry. Therefore, after shampooing, Indonesians apply coconut oil to remoisten the hair. (See: Kompas - In Indonesian).

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Description

Shampoos clean hair by stripping sebum. Sebum is an oil secreted by the skin cells on the scalp that coats the hair. Because it is oily, the sebum tends to collect dirt, styling products and scalp flakes. Surfactants by strip the sebum from the hair shafts and thereby remove the dirt attached to it.

While both soaps and shampoos contain the cleaning agent surfactants, soap is specifically designed to clean the body and might be too harsh on hair.

The differences between shampoo and soap include:

The chemical mechanisms that underlie hair cleansing are complex. Undamaged hair has a hydrophobic surface to which skin lipids such as sebum stick. The lipids do not come off easily when the hair is rinsed with plain water. When shampoo is applied to wet hair, the anionic surfactants are adsorbed onto the oil/air/water/hair interfaces. The surfactants substantially reduce the interfacial surface tension and allow for the removal of the sebum from the hair shaft. The semi-polar oily materials on the hair shaft are also solubilised into the surfactant micelle structures of the shampoo and are removed during rinsing. There is also considerable removal through a surfactant and oil "roll up" effect. The details of the cleaning mechanism off surfactants is very complicated and is the subject of continuing research in academia.

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The Ingredients

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Detergents

Surfactants, also known as wetting agents, lower the surface tension of a liquid, allowing easier spreading, and the interfacial tension between two liquids. The term surfactant is a contraction of "Surface active agent".

The major types of surfactants are used in shampoos include:

Alternate shampoos, sometimes labeled SLS-free, have much less harsh chemicals and none from the sulfate family. While gentler on human hair, these shampoos often have to be applied multiple times in order to effectively remove buildup.

Many shampoos are pearlescent. This effect is achieved by addition of tiny flakes of suitable materials, eg. glycol distearate (a wax).


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Additives, Useless and Otherwise

In the USA, the FDA mandates that shampoo containers accurately list ingredients. The government does regulate what shampoos can or can not claim and any benefits associated. In many cases, competitors can and regularly do challenge marketing claims made so there is accountability regarding what can be said. While the claims may be substantiated however, the testing methods and details of such claims are not as straight forward. This has lead to claims regarding certain ingredients that can and do provide for example protection from ultraviolet light preventing colour fading even if the actual level of that ingredient is insufficient in the shampoo to achieve that benefit.

Vitamins and pro-vitamins and amino acids, advertised mostly by Pantene Pro-V, are primarily helpful if ingested. Since your hair isn't living, it can't make active use of vitamins or minerals. However, hair strands are made up of multiple helical proteins composed of amino acids and other biological materials. In many cases, weathering and exposure to water can result in parts of the hair being drawn out, leaving holes or gaps. This is similar in effect to what can be found in silica glass and the holes that form from regular washing. Addition of some materials can fill in those holes and restore some vitality to hair strands though what molecules and what levels are required is less well known.

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Specialized shampoos

Cosmetic companies have developed shampoos specifically for those who have dandruff. Dandruff shampoos contain fungicides such as zinc pyrithione and selenium sulfide which reduce dandruff by killing Malassezia furfur. Coal tar and salicylate derivatives are often used as well.

Some companies use "all-natural" or "organic" or "botanical" ingredients, such as flowers and the like, often combining these additions with a harsher base. The effectiveness of these organic ingredients is controversial.

Shampoo for infants is formulated so that it is less irritating to the eyes. Most contain sodium laureth sulfate, the mildest surfactant of the sulfate family. Alternatively, many infant shampoos are also formulated using other classes of surfactants, most notably non-ionics which are much milder than any charged anionics used.

Shampoo for animals (such as for dogs or cats) should be formulated especially for them, as their skin has fewer cell layers than human skin. Cats' skin is 2-3 cell layers thick, while dogs' skin is 3-5 layers. Human skin, by contrast, is 10-15 cell layers thick. This is a clear example of why you should never use baby shampoo on a cat or dog.

Shampoo intended for animals might contain insecticides or other medications for treatment of skin conditions or parasites such as fleas or mange. It is important to note that while most human shampoos are appropriate for animal use, products that contain active ingredients/drugs such as zinc in antidandruff, are potentially toxic when ingested in large quantities by animals (but not humans) and special care should be taken to avoid use of those products on animals.

Shampoo is also available in solid form, allowing it to be rubbed onto the hair. This has the advantage of having the shampoo easily carried, but also has the disadvantage of working less efficiently on longer hair.

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See also

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References

de:Shampoo fr:Shampooing lb:Shampoing nl:Shampoo ja:シャンプー pl:Szampon pt:xampu fi:Sampoo sv:Schampo

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