A brush earns its place mid-wash, once the shampoo's on for its second round. It does two quite different things, depending on where you use it.

At the scalp, it helps clean. Wet hair is fragile, so you'll want a brush made for it. On that second round of shampoo, work the brush over your scalp in small circles. It lifts away the tired surface skin and reaches across evenly, more than fingers usually manage. Just the once, though. There's no need to pile it on top of other scalp treatments in the same wash.

On the lengths, it does the opposite. Once your mask or conditioner is on, part your hair into sections, sit the brush tips at the ends, and draw slowly upward. It's the most even way to move a product down the hair, and it helps the mask rinse out more cleanly after.

Here's the part that changes: keep the brush off your scalp now. Down the lengths you're spreading care evenly, but up at the roots the same motion just works product into the skin, which it doesn't need. So the lengths are the brush's job, and the roots stay with your hands.

Written down it sounds fiddly, but after a wash or two your hands just know.