I use Evapo-rust everyday. There's always a batch going on. I dunk old vials on those levels and combination squares etc.... the only way evapo-rust would get in is if that vial is no good in the first place. Some of them are glued in and the evapo-rust does not damage the glue.
When I paint those levels, (if using spray paint),I use Vaseline on manicure/pedicure Q-Tips.... Rub Vaseline on the vial, paint, dry, wipe off Vaseline.... Too hard to get masking tape in there.
Oh yea, evapo-rust will clean vial, but clean it with alcohol and Q-Tip prior to Vaseline.
Also, 1982fxr, I see you've been using evapo-rust a lot more lately. You can dilute it quite a bit btw, and it still works.
What I do example: all metal tilting mill table I just did. It had decent rust going on, but still a user. I degrease big stuff out in lawn, then put in ultrasonic with purple power for a day (soak 23.5 hours,run machine for last .5 hour).... That alone removes most of the rust. Then I take it outside and hose it off really good. Then I put it in evapo-rust to fine-tune it and get it perfect. That way I'm not using up all my expensive evapo-rust.
On big heavy ugly stuff like a big vise that's really rusty I do citric acid powder mixed with water and a big sterilite container. That removes all the rust...but it will flash rust. So I hose it off. And then I will put it in evapo rust because it seals it.
I buy a 5lb bag of citric acid powder on Amazon for $15 and it will easily make 40 gallons or more.