So how long should it take for my lines to get darker? Took 4 FRER tests... 1 yesterday fmu, 1 yesterday mid morning, 1 yesterday evening, and 1 this morning with fmu. Seems like the ones from the evening and this morning are a bit darker than yesterday morning, but the one this morning is about the same shade as the evening one from yesterday! I know I sound obsessive but I just turned 40 and I had a chemical