From straightforward styling to elaborate perms, from a temporary tint to a platinum bleach, all these processes depend on changing part of the structure of hair. The stylists and technicians who have to apply them are expected to have a thorough understanding of hair structure, the hair growth cycle and the continuing care of hair. They need a working knowledge of the disorders of the hair and scalp, the chemistry of hair care products and the ways in which they protect the hair, and the science that underlies the various cosmetic procedures.
    Just as a doctor takes a 'history' of a new patient in the surgery, so the stylist looks at the history of a client's hair and examines its condition, in particular whether there is evidence that it has been chemically treated previously. The doctor can only decide what can be done for the patient once that history is known and understood: in the same way, the most expert stylist can only decide what is or is not possible after that examination has been made.

Styling hair

Styling hair means temporarily or permanently altering its shape. We shall discuss perming in the next section. Here we are talking about the temporary changes brought about by setting the hair. Setting is different from perming in that

there is no chemical reaction in the hair. All that happens is that some of the weak hydrogen bonds are broken by water and then re-form in the newly positioned hair as the water evaporates.
    A curl can be produced by setting hair on a former such as a curler or roller - that is, allowing wet hair to dry while twisted round the former. (Fixing wet hair into pin curls has a similar effect.) After the curlers or rollers have been removed the hair holds its shape until it gets wet again.
    In a perfect world, the hair could be left to dry naturally on the curlers or rollers and then combed out with a broad-toothed comb. But the pace and hurry of modern life makes this a luxury that we cannot afford, and some kind of