Damaged hair - what causes it and what can be done

“Damaged” is a word we all use for different things: hair that breaks, hair that looks dull, hair that frizzes, hair with split ends.

They are separate problems with separate causes. Which is why there is no single treatment that suits everyone - first you have to work out which of the main causes is doing the most.

The three usual causes

Repeated lightening. To lighten hair you have to open the cuticle, the outer layer that protects it. That is the mechanism, not a mistake: every lightening takes something out. The problem starts when you push too far in one go, or repeat it on hair that has not recovered.

Heat. Very hot straighteners and dryers, used daily and without protection, do slow but constant damage. You do not have to stop using them: you have to turn them down and put something between the heat and the hair.

Friction. Brushing hair while it is wet, tight elastics always in the same place, rubbing with a towel. Small habits that nobody connects to the damage, and that break hair halfway down the length.

Usually all three are contributing. Working out which one weighs most does two things: it tells us which treatment to use, and which habit to change so the damage stops while we repair it.

What a treatment can do

It can rebuild from the inside, filling gaps in the structure so the hair is more elastic and less brittle.

It can seal the cuticle, so hair reflects light rather than absorbing it - that is why some treatments make hair look shinier straight away.

It can calm frizz, which is often not damage at all but a cuticle that is not lying flat and lets in moisture from the air. In Florence, in summer, this is more common than actual damage.

What it cannot do

It cannot close a split end. The hair has divided in two: it can be sealed for a while, but it comes back. Cutting is the only way to remove it.

Anyone telling you otherwise is selling you something.

It also cannot make lightened hair identical to virgin hair. It can be improved a great deal, and can feel genuinely good again, but structure that has been opened stays more fragile than structure that has not.

Why we look before suggesting anything

It would be easier to have one good treatment and offer it to everyone. It would work for some, and the rest would pay without seeing a result.

Instead we feel the hair wet: how it responds when stretched, how much it absorbs, how long it holds water. Those things read in a moment and tell you more than any description.

Then we choose. And if the hair needs cutting more than it needs treating, we say that too.