Two OPK strip questions

kat81

I'm pretty new to OPKs and I'm still not sure how I feel about them. So first of all, I'm using expired strips. I bought them last cycle and they came in a sealed tube. There were 30 or so of them, and I didn't use them all, figuring I'd use them the next later cycle. Well, the package said they expire after 30 days after opening the container. I probably opened it more like 40 or 50 days ago. Great. Why sell so many in a sealed container like that if you're going to make them expire? But I didn't want to not use them at all.

I have used them the past few days and gotten negative readings. But today, I think I got a positive. It was close, though, because the lines were about the same darkness (test not definitely darker than control). So, two questions:

1)  What do you know about using expired strips? Prone to false positives? wonky results one way or another? Are expiration dates just for show or are they to be taken very seriously?

2) Do you know the usual deadline for "do not read this after this time"?  I'm a complete idiot and I threw out the instructions for these strips as I was cleaning my bathroom. I read the test right away, but the longer I left it, the darker the test line got. I think it was equivalent darkness to the control line within a couple of minutes, though. I'm just curious if you know whether leaving it to sit for a while causes a false positive.

I wasn't expecting to ovulate for at least another week, but you never really know with my cycle. And I got CM that was quite EWCM-seeming this morning (and I posted about that, too...sorry). 

ecubaby19

I'm not sure about why they expire but the last strips I used said not to read after 5 minutes but I think it varies from brand to brand!