I found out on here recently that you don't need to use up a box dye in its entirety in one go, people apparently use as needed and close? (Blew my mind).
I am prematurely greying (early 30s, VERY grey, started greying in late teens) and just want to dye my roots. For years I would use 1 (or 2 when long) boxes concentrating on the roots then running through rest of shafts but find the process time-consuming and can be a bit messy. My question is, would it be acceptable to only mix enough dye to dye the roots? I think it would save a lot of time and effort/ less mess / dripping etc. Do any of you do this?