A scalp serum that leaves your colour alone.

Why colour-treated hair is where thinning shows first

Grey hair is finer than the hair it replaced, and colour-treated hair is more porous. Both read as less density under bathroom light, and both sit on a scalp going through the same estrogen drop as everyone else's. So the widening part often shows on grey and highlighted hair first — not because the colour caused it, but because there is less to hide it.

What the serum is, and where it goes

Both Boon Labs serums are clear and water-based. They go on the scalp — the skin at the part — not down the strand. There is no oil to sit on the hair and nothing that stays on the surface to warm a toner. Applied as directed, one dropper at the part with thirty seconds of massage, the hair itself barely meets it.

It sits on the scalp, not on the strand. That is the whole reason it is a serum and not an oil.

How to test it on yourself, fairly

We do not ask you to take our word for it. On day one, before the first full application, put one drop on a hidden section behind the ear — scalp and the first inch of hair — and leave it overnight. Look at it in daylight the next morning. No warmth, no dulling, no irritation: carry on. Anything you do not like: stop, email us, and we refund it regardless of how long you have had it.

If you have a gloss, toner or colour appointment coming up, apply the serum after the appointment that day rather than before, and tell your colourist you are using a water-based scalp serum. Most will simply nod.

The routine

The Density Serum every morning at the part. The Shed Serum at night while shedding is active, then stop. Two minutes, nothing to rinse, nothing greasy at the roots by lunchtime — which matters more on fine grey hair than on anything else.