I did suggest submerging it long enough to allow the lube to come off and gather aat the surface (that would defeat the purpose of the test all together) I said dunk as in in and out in under a second, and space them to make cross contamination difficult.
secondly stainless screws would handle your other issue.
aside from that its your test, do it how you like, I think its a neat idea, I just saw others making their suggestions and followed suit, didn't think I'd be the only one to get flat out shot down.