Blue dye tests

I know blue dye aren’t great, I’ve already taken 6+ frer and they were all faintly +

I am having blood work done today

I took this cheap blue dye yesterday and it was hard to tell it positive but noticed this an hour later. I know I’m not supposed to look later but I’m curious why it’s blue ... I know evaps are usually thin and/or grey but this is thick and blue. Anyone have experience with blue dye?

**Edit**

I took another test this morning and this showed up within a couple minutes in the timeframe