I just used the 3M lead test on this wall and I’m finding it difficult to interpret? There is this wallboard with recent paint on it, and underneath seems like a layer of wallpaper and it seems rust colored in places. With the rust colored test liquid it’s getting confusing. Can anyone help? Do we have lead? House built in 1948, renovated before we bought it in 2013.
The details for the 3M LeadCheck product read:
turning bright pink when lead is present
I don't see any "bright pink" in your photo, so it seems that there isn't a significant amount of lead present.
Your test kit should contain a "Test confirmation card" which you can use to compare your results with their examples.
Even if it did indicate some lead though - if you have to tear the walls apart to get to it, then it doesn't matter. Lead in paint is harmful when ingested, so unless you or someone you know is planning to eat your walls, you'll be fine.