Brad Johns invented a hair-coloring technique named, without any softening, for exactly what it does: chunking, in which sections of lighter color go in as visible blocks rather than the fine, blended strands frosting caps had produced for decades. He died this week at 70, at his home in West Hollywood, after a long illness. He first used chunking on Christy Turlington in the early 1990s, while working as color director at Oribe's salon on Fifth Avenue — a technique invented, like most real innovations in a service industry, to solve one client's hair rather than to found a movement.

It found the movement anyway. Kate Moss, Carolyn Bessette Kennedy, and Johnny Depp all sat in his chair over a four-decade career built on the same refusal — that a color job had to look inevitable rather than invisible. Dimensional color, the layered, sun-loosened blonde sold now in every drugstore box, descends in a straight line from a colorist willing to leave the seams showing instead of hiding them. It's on heads today that have never heard his name.

The chunks were never meant to blend — that was the invention.