Forget turning your hair into denim, or a galaxy far, far away, or oil slick or a macaroon parlor, the latest thing is to have a covert rainbow hiding behind your head. "Hidden rainbow hair" is the upgrade on fluorescent locks that makes merely Technicolored hair obsolete.

The trend has taken over London, championed by another salon called Not Another Salon.

Hidden rainbows are all the London rage right now. #hiddenrainbowhair #hiddenrainbow #rainbow #rainbowhair by Carla

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