Question ....how do these tests work? Lol

[LoveMy2Boys2]

So I have taken a ton of dollar general tests this month ..... And I keep getting pos within the time frame but after 10 min it's starts fading into basically nothing :/ ....... The directions say check at 3 min and if no line let it sit 1 min more and do not read after 10 min...... Now would this possibly be because after 10 min the result can fade ? Or does it just mean evap?
Ugh I just need a frer ....
Thanks!!

 

[popchick75]

Any pictures?