Hair after summer is not just dry - it is loaded. Heavy metals from the tap, chlorine deposits, residue from everyday products and badly fixed dye settle inside the shaft and change how it behaves. The result is not just less shine. The result is hair that stops responding to any product you put on it.

And there is the point the industry does not say out loud: if the shaft is clogged, the expensive new product has nowhere to go. You are paying for a treatment that works on top of a barrier.

What chelation is

Paz Torralba, founder and director of a Spanish salon group, explains it as a chemical process in which specific agents bind to the metal ions deposited in the shaft and neutralise them so they can be flushed out. The difference from ordinary deep-cleansing shampoos is depth: those work on the surface, chelation goes from the cortex to the cuticle.

"Hair arrives at our salons with an accumulated history: chlorine from pools, limescale from the water, residue from badly fixed dye. Chelation makes everything that comes afterwards actually work," she says. Protocols such as L'Oréal Professionnel's Metal Detox, or Malibu C's suggestions for hair exposed to hard water, carry the same logic.

Why this makes sense specifically in September

According to Torralba, removing the residue that forms a barrier between pigment and shaft means the colour fixes more precisely, the tone lands closer to what was expected and the brightness lasts longer. Chelation also reduces porosity, so the shaft stays more compact and even - which in practice means less frizz and more manageable hair in humidity.

The shine that appears afterwards is not applied on top. It is the shine of a healthy shaft, which is an entirely different thing from shine that washes out with the first shower.

So it is not a treatment done instead of everything else - it is the step before everything else. Before colouring, before straightening, before reconstructive masks. Get the order the wrong way round and the money for the treatment is already spent for nothing; you just do not know it yet.