PSA: I used 20 volume on a client's roots and got banding I had to fix for free
Last Tuesday I did a root touch up on a regular at my chair in Reno and mixed 20 volume out of habit instead of 10, and her roots lifted two shades lighter than the rest. I had to tone it down and skip my lunch to fix it, and she still tipped me, which honestly felt worse. Now I write the volume on the bowl with a marker so I stop grabbing the wrong bottle. What do you all do to keep your developer straight on busy days?