If you can see a line in an invert photo does that mean it’s not an evap and it is definitely a proper positive line? I read evap lines don’t have colour and so won’t show up when the photo is inverted. Anyone know how true that is?

I took a test this morning and had a faint line but took a clearblue one in the afternoon and it was negative so wondering could this be an evap. The photo was taken at just under 10 mins after testing which the instruction said is within timeframe.