Uneven hair color: what I check before correcting

It happened to me in a real situation during a color service with an unclear history. The problem was that the client had areas with old bleach, and the tone ended up uneven in the mid-lengths and ends. At first, it didn't seem serious, but in a real work environment, that kind of detail can affect times, costs, or client trust. I didn't settle for the first explanation. I checked the formula…