Shampoo, when lathered with water, is a surfactant, which, while cleaning the hair and scalp, can remove the natural oils (sebum) which lubricate the hair shaft.

Shampooing is frequently followed by conditioners which increase the ease of combing and styling.

History

Shampoo originally meant head massage in several North Indian languages. Both the word and the concept were introduced to Britain from colonial India. The word shampoo in English is derived from Hindi chāmpo (चाँपो /tʃãːpoː/). Its English usage in Anglo-Indian dates to 1762. In India the term chAmpo was used for head massage, usually with some form of hair oil.

The term and service was introduced in Britain by a Bengali entrepreneur Sake Dean Mahomed in 1814, when Dean, together with his Irish wife, opened a shampooing bath known as 'Mahomed's Indian Vapour Baths' in Brighton, England. His baths were like Turkish baths where clients received an Indian treatment of champi (shampooing) or therapeutic massage. His service was appreciated; he received the high accolade of being appointed ‘Shampooing Surgeon' to both George IV and William IV.

In the 1900s, the meaning of the word shifted from the sense of massage to that of applying soap to the hair. Earlier, regular soap had been used for washing hair. However, the dull film soap left on the hair made it uncomfortable, irritating, and unhealthy looking.

During the early stages of shampoo, English hair stylists boiled shaved soap in water and added herbs to give the hair shine and fragrance. Kasey Hebert was the first known maker of shampoo, and the origin is currently attributed to him.

Originally, soap and shampoo were very similar products; both containing surfactants, a type of detergent. Modern shampoo as it is known today was first introduced in the 1930s with Drene, the first synthetic (non-soap) shampoo.

In India, the traditional hair massage is still common. Different oils and formulations with herbs may be used; these include neem, shikakai or soapnut, henna, bael, brahmi, fenugreek, buttermilk, amla, aloe, and almond in combination with some aromatic components like sandalwood, jasmine, turmeric, rose, and musk.

How shampoo works

Shampoo cleans by stripping sebum from the hair. Sebum is an oil secreted by hair follicles that is readily absorbed by the strands of hair, and forms a protective layer. Sebum protects the protein structure of hair from damage, but this protection comes at a cost. It tends to collect dirt, styling products and scalp flakes. Surfactants strip the sebum from the hair shafts and thereby remove the dirt attached to it.

While both soaps and shampoos contain surfactants, soap bonds to oils with such affinity that it removes too much if used on hair. Shampoo uses a different class of surfactants balanced to avoid removing too much oil from the hair.