Warning: check the neck and ears before you trust a new color client's story
I had a client in Denver swear she hadn't colored her hair in over a year, so I mixed a level 6 ash without a strand test (dumb, I know). Her mid-lengths grabbed green in about 10 minutes, and it turned out she'd been using a box dye with metallic salts back in March. Now I run a quick test strand behind the ear and ask for a photo of their bathroom shelf before I mix anything. Anyone got a faster way to screen for box dye buildup?