Split ends and breakage: causes and prevention

A hair strand has an outer layer of overlapping cuticle cells protecting an inner cortex. When the cuticle wears away at a point, usually near the end where the hair is oldest, the cortex is exposed and the fibre begins to fray along its length.

Hair is not living tissue and has no repair mechanism. Once split, that strand is split. Products described as repairing split ends are coating them so the frayed sections cling together temporarily. It looks better and it washes out. That is a cosmetic fix, not a repair, and it is fine as long as you know which you are buying.

• Age. The ends of long hair are years old and have been through thousands of washes and combings.
• Mechanical friction: brushing, towel-drying roughly, hair rubbing against collars and pillowcases.
• Heat. Straighteners and dryers at high temperature damage the cuticle directly.
• Chemical processing: colouring, bleaching, relaxing and perming all lift or disrupt the cuticle.
• Dryness. A dry, brittle fibre fails sooner than a supple one.
• Handling wet hair carelessly, which is when it is most extensible and most easily damaged.

Small white specks along the shaft, not at the end, are early structural failures where the cuticle has worn through and the cortex is exposed. They are the point at which the strand is about to snap.

They are more useful than split ends as a signal, because they tell you damage is occurring in the mid-lengths, which usually means brushing or heat rather than simple age. If you see them, look at your handling rather than reaching for a mask.

A split does not stay put. It travels up the strand, and the higher it climbs the more length you eventually lose. Cutting off two centimetres now often saves five later.

This is why people growing their hair who refuse all trims frequently end up with less length than those trimming regularly. The ends thin out, snap unevenly, and the overall length plateaus while looking increasingly wispy.

Every few months, taking off only what is damaged, suits most people. If you are unsure, look at the last two centimetres in good light.

1. 01Detangle before washing, dry, from the ends upward. Wet tangles are much harder on hair.
2. 02Use a wide-tooth comb rather than a brush for detangling, and never force through a knot.
3. 03Blot and squeeze hair in a towel rather than rubbing. An old cotton t-shirt is gentler than a terry towel.
4. 04Reduce heat styling, and when you use it, keep the temperature down and use a protectant.
5. 05Keep the ends conditioned. This is where oil and conditioner do their most useful work, because the ends are the oldest and driest part.
6. 06Reduce overnight friction with a smooth pillowcase or a loose braid.
7. 07Trim on a schedule rather than waiting until the ends look bad.

This is one of the areas where oiling has a straightforward mechanical rationale. A lubricated strand experiences less friction when combed, and less friction means less cuticle wear. Applying oil to the mid-lengths and ends before washing also reduces how much the hair swells and stretches during the wash.

It does not mend a split. It reduces the rate at which new ones form. That is a modest claim and a real one.