Over the last week or so I have evap tested 3 different cans of naphtha.
All are brands I have used before that evaporated clean & left no visible residue or oililness behind.

Normally I do evap tests on a well cleaned Pyrex dish, this time I did the evap tests on a mirror & the results were ALL dirty.

It seems very strange to me. I went back & cleaned the mirror thouroughly & then cleaned a Pyrex dish the exact same way.

Evap tests on the dish left no residue from any of the containers, but the mirror always shows residue.

It really makes me question whether there is any naphtha that can be found locally that would evaporate cleanly on both a mirror & Pyrex dish & whether the naphtha I have been using is safe.

Only thing I could think of is super porous, low quality imperfect glass in the mirrors. Thats the only thing that could make sense in my eyes.

At first I thought it may have been that the mirror caught something very minimal or made it more apparent due to the reflective surface but now that you say that It does seem like mirrors are made of lesser quality glass than pyrex.

I think a search for a borosilicate mirror is in order