I can't seem to find an NPS that passes the evap test. I have tried Bestine brand heptane, "BVV Ultra High Purity Lab Grade N-Heptane 99.3%", Klean Strip MEK Substitute, Klean Strip Naphtha, and a few other brands, as well as multiple different batches of some of those. For some reason I can't get any of them to pass an evap test on a mirror. I keep getting white watermark rings after evaporation like these: https://imgur.com/a/mkUMoDI. The first one is bestine, the other two are Klean Strip EA and naphtha.

Some of them leave more rings, some less, but none of them have dried perfectly clean.

My procedure is with a small mirror that I scrub over with 70& iso and a paper towel a few times. Is there something wrong with my cleaning procedure, are my expectations too high, or am I just unlucky with all of these different NPSs?

The ring could be from particles in the air concentrating there. I think your expectations are too high. Try scraping up any "product". Is there anythkng visible in the razor blade you could load?

You can also do a distilled water or IPA evap test to see if the rings still appear and could come from air drying.

Note that you already breathe in this air gunk all the time (if that is where the rings are coming from).

Good call on testing water and IPA on their own as a control, yeah they have similar marks. Looking at some examples of failed evap tests, they straight up have rainbows dried up on their glass. You think if I dried this in a still air box or a laminar flow hood, the mark wouldn't show? Or are the particles too small and numerous for those?

I'm happy with the results now, so just asking this out of curiosity.

I use the same brand of Naphtha and I didn’t do an evap test (did know i was supposed to but I was told by others to use that brand), and I haven’t experienced any negative effects with the results of my extractions. I get pale yellow crystals that seem to be good compared to descriptions on this site and in personal tests. You are probably good to go in my opinion. Good for you for making sure. Better sage than starry, I always say.

-Tripp