Hair
waving and straightening methods
There
are three basic methods to style or straighten hair: 1) the application
of pomades and oils, or resin based fixatives, 2) using heat from
a comb, rollers or iron (hot pressing), and 3) the use of chemical
processes. Until relatively recently oil based pomades and creams
or resin based sprays were the most popular method for straightening
or styling hair at home. Hot combing and chemical processes were
relatively complicated and potentially hazardous and so largely
restricted to the professional salon. With an advancement in chemical
formulations and simplification of the application procedure in
the late 1960s so at home chemical processing kits have become popular
and more widely available. Hot combs and irons have been with us
a long time, but until the development of internal heating elements
and thermostats to limit the heat level, combing and ironing were
time consuming and brought dangers of hair damage and skin burns.
Each of these three approaches; oils and resins, hot combs and
irons, and chemical processes, has advantages and disadvantages.
Oil and resin based fixatives are only temporary cosmetic products.
They hold the new style for a day or two before they have to be
reapplied. However, their temporary nature provides the advantages
that you can change the style of your hair as often as you like
and the products will not do significant damage to the hair. Hot
combs and similar can cause hair damage if they are overused, but
if used correctly can give a reasonable result without too much
effort. The effects of hot combs and rollers are also temporary,
but last a little longer than using oils and resins. Chemical processes
in the salon or at home give the most permanent results, but they
also carry the risk of greatest damage to the hair. Chemical processing
requires extensive alteration of the biochemical bonds in hair fibers
to allow the new style to be made and fixed in place. If not conducted
properly, chemical process can lead to permanent weakening of the
hair, hair breakage, and even hair loss.
Hair
waving procedure
Hair waving and straightening methods have been used for thousands
of years. At their simplest, products made from oil and grease were
applied to the hair to alter its shape. In the early 20th century
hair waving and straightening was done mostly using machines of
some kind that applied heat to the hair to set it in a particular
style. Chemical preparations have been around since the mid 1940s.
Also called "cold wave" preparations these straighteners
and hair waving products involve chemically rearranging protein
bonds in the hair to obtain the desired effect.
Most modern chemical preparations for hair waving available today
are based on chemicals called thioglycolates (sometimes known as
Jherri curls). The process involves two key steps. First, the thioglycolate
chemical is applied to the hair. This "softens" the hair
by breaking the disulfide biochemical bonds that naturally form
between keratin proteins and give hair its shape and strength. The
chemicals are applied for a short period of time, say ten or twenty
minutes, to make the hair pliable. At this point the hair is relatively
fragile. The hair is formed into the desired shape or straightened
out or whatever effect is required. Curlers, rollers, combs and
other physical methods are used to get the hair into the right shape.
The chemical process is then neutralized, usually by extensive washing
with water to remove the thioglycolate solution and then application
of an oxidizing agent such as hydrogen peroxide. Some kits allow
for neutralization through air oxidation, but this process is usually
very slow and so it is not a popular approach. In either event,
the principle is the same, to remove the thioglycolates and promote
reformation of the biochemical bonds in the hair. The biochemical
bonds between keratin proteins in the hair reform as the chemicals
are washed out and oxidizing agents applied. If the hair is held
in the right position during this neutralization and oxidation step,
the reformation of these biochemical bonds will fix the hair in
the new shape.
|
