False Positive?

[Sah15]

Hi,
Has anyone had false positive on clear blue, this was negative at first then I checked a couple of hours later and it looks positive?
Any sucess stories?

These tests are notoriously bad of evap lines! I’ve been confused in the past and now won’t touch any blue ink tests. Try a FRER, they’re so much more reliable xx

I had this a couple of months ago and it was evap lines.
Best using pink dye e.g. FRER x

I had the exact same thing multiple times. They're absolutely awful for it. Blue dye tests in general are. Get an FRER (NOT from online) and that's the only way you're going to know for sure

They are only valid to read within the time frame of the test instructions. Anything which reveals after that is irrelevant I'm afraid.