From straight to curly, curly to straight, and everywhere in between, millions of people
each year do something to change the texture and wave patterns of their hair. It's big
business. There are many rules to remember, and some myths that need to be
dispelled. So, let's talk about hair and perms.
Hair 101:
Your hair is made up of proteins. Each strand has a cortex at the
center. The cortex is made up of proteins in a chain down the length of
the shaft. These proteins (called poly-peptide chains) are held together
by peptide bonds which give the hair its strength.
Surrounding the cortex is the medulla, again made of protein fibers
and containing the pigment of the hair, giving the hair its color. Here is
where you'll also find the side bonds of the hair, which hold the wave
pattern of the hair. There are three types of side bond: salt bonds,
hydrogen bonds and disulfide bonds. The salt and hydrogen bonds
are weaker than the disulfide bonds, but there are more of them, and overall, each of
the bond types constitute about a third of the strength of the hair's curl. The disulfide
bonds are what get changed in a permanent wave.
Finally, the cortex and medulla are encased in a protective sheath called the cuticle.
The cuticle is made of tiny, overlapping scales of keratin (the same thing fingernails and
toenails are made from). The cuticle is what protects the hair from damaging effects of
the environment. Some people have hair with a tightly closed cuticle, and some have a
cuticle whose normal state is slightly raised. The arrangement of the hair's cuticle
determines how readily the hair absorbs moisture, and how "frizzy" the hair appears to
be.
Curling The Hair:
We change the wave pattern of the hair by curling it, usually on rollers of some type.
These changes occur because we alter the side bonds of the hair. The salt and hydrogen
bonds mentioned above are easily broken through the application of water and heat,
which is why simply wetting the hair, wrapping it in rollers, and allowing it to dry - or using
a curling iron - allows you to add curl. When the heat cools and the hair dries, the salt
and hydrogen bonds reform on their own. The curl you get this way only lasts until the
next time the hair is wet. Hot combs and flat irons work on the same principles to relax
curl and straighten the hair.
Perming The Hair:
The process we call permanent waving uses chemicals to break and reform the stronger
disulfide bonds of the hair. When the hair is washed and wrapped on a perm rod
(the rod size used determining the tightness of the curl), we place the hair in the physical
shape we want it to take. Then, by applying a waving lotion with an alkaline base
(ammonium thioglycolate is most commonly used in today's perms), we raise the cuticle
layer and break the disulfide bonds that hold the natural wave pattern.
After the waving lotion has had time to process and has been rinsed away and the
rods have been blotted to remove excess water, and a neutralizer is applied. The
neutralizer is actually what reforms the disulfide bonds of the hair and sets the new curl
pattern. It is also the most potentially damaging stage of the perming process and
should always be closely monitored.
Once allowed to take effect, the neutralizer is rinsed away, the rods are removed, and
the hair is re-rinsed for good measure, it can be styled as desired.
