Hi,
I have used them three times in last week and got one which wwas nothing at all (yesterday) but on Fri and today (from different boxes bought in different places) I have got a line very quickly but very faint that lasted for about two mins and which then disappeared so at the ten min mark which is when you're supposed to read them despite having had a line there was nothing there but which then, and hour or two later, developed into a definite line (blue, so not evaporation), which has stayed there.
Is this normal for clear blue? If nothing there at 10 min is it definitively negative? If line developes properly after some time is that always counted as negative.
Thanks for your thoughts and experiences.