HOW FRICTION DAMAGE STARTS
Each strand’s outer layer, or cuticle, is made up of scales on the surface of the hair and a lipid protection barrier (a fatty layer of molecules) that keeps the scales soft and flat, Martina says.
When friction damages that natural shield, it causes the scales to flex upwards and can even pull them off, leaving holes in the cuticle. This exposes the cortex – the inner structure of the hair – which is comprised of bundles of a tough protein called keratin (they look like cables with hundreds of wires wound around them). “When these bundles fray, you get split ends,” Martina says. And when you tug – to comb or pony up – the weakened hair breaks.