Tell me about… Chemicals used in hair treatments

My sister changes her hairstyle quite frequently. One month, she is rebonding her hair. The next, she is perming it. I told her that this damages her hair, but she doesn't listen. Actually, what is rebonding?

Rebonding is the art of straightening your hair using chemicals.

Hair is made out of a protein called keratin. Keratin is also present in your nails. In hair, the keratin molecules are in straight bundles. These bundles are held together tightly by disulphide bonds. (Di = two, sulphide = containing the sulphur element).

These bonds are made from cysteine, an amino acid. The cysteine of one keratin molecule makes a disulphide bond with the cysteine of another keratin molecule next to it.

The bonds make your hair strong.

The more disulphide bonds you have you in your hair, the straighter your hair is.

So what does rebonding do?

Rebonding uses a salt called ammonium thioglycolate. It is the same salt that is used in perming your hair to make it curly.

Ammonium thioglycolate contains a thiol group (-SH) that can break disulphide bonds through a chemical process.

Once the disulphide bond is broken, the keratin bundles that are connected in your hair come apart. Your hair is definitely weakened.

During the rebonding process, the hairdresser will wash your hair, then apply this salt on it for a short while. The salt will work its process and loosen your hair.

Then, once the disulphide bonds are broken, your hair is pressed together with hot irons to straighten it. After it is straightened, your hair needs to be strengthened so that the hairstyle (in this case, straightening) becomes permanent.

For this, an oxidation compound containing hydrogen peroxide which reconstitutes the disulphide bonds is applied.

Voila! You now have "permanent" straight hair.

You mentioned that the same salt is used to perm hair. What is the difference?

The hairdresser goes through the same process in using the ammonium thioglycolate. The difference comes in what happens after the salt is washed off.

Instead of straightening your hair, like in rebonding, the hairdresser ties your hair around curlers instead, and makes it "permanent" with the oxidation compound.

Is this the same thing as keratin therapy?

No. Keratin therapy is actually a therapy that fills the gaps between the disulphide bonds with keratin instead of breaking them down. When you infuse keratin into your hair cuticle, you can reduce your hair's frizz and curl by as much as 95 per cent.

Keratin therapy is actually less damaging to your hair. It makes your hair glossier and healthier. But it only lasts for four to five months.

Is rebonding safe for your hair?

No, it actually isn't that safe.

In fact, it can make you bald if you do it too often or if you don't do it the right way. It can also damage your hair for life.

Rebonding, for example, exposes your hair to chemicals and dryers that may dry up your hair roots. This makes your hair extremely vulnerable to breakage, resulting in hair loss. That is why it is always best to do rebonding at a professional hair salon.

Your hair can also be burned or damaged. You may experience split ends.

Some people actually complain of hair falling in clumps after rebonding.

If you keep on drying or blowing your hair excessively, this can result in permanent hair loss.

You can also be allergic to the chemicals, causing itchiness and blisters to your scalp.

That is why, before you do rebonding, be aware of all the side effects that can occur. It doesn't mean that they will occur all the time, but it CAN happen, and you should be aware.

What is the difference between rebonding and 'relaxing' your hair?

Relaxing uses the same kind of technique to break down and reform the disulphide bonds. But relaxing is not permanent. It only lasts for two or three months.

Hair relaxing uses ammonium thioglycolate as well, but in higher pH and concentrations than used in permanent straightening.

It can also cause irritation and many of the side effects found in rebonding.