10-21-2017, 06:41 AM
A poster on the Dpreview stated that while at a service center, he witnessed a technician cleaning a DSLR mirror with a sensor paddle and a "fluid" .. to all intents and purposes he was also an "actual human being" at least outwardly! 
As to what metal is used is difficult to find out, some say aluminum some silver, early mirrors were coated with an amalgam of tin and mercury, it could well be a more modern amalgam to make it more resistant to corrosive air attack, the mirrored side being exposed to the air.
The danger is the semi-mirrored area which is thin to the point of being translucent.......but......
.... wait, Yay!.. I have a dead donor Samyang GX10 which is no use to me.......... I will clean it's mirror (gently) and let you know the result.....
.....however, I'm not sure if the mirror.......... is species sensitive!
As to what metal is used is difficult to find out, some say aluminum some silver, early mirrors were coated with an amalgam of tin and mercury, it could well be a more modern amalgam to make it more resistant to corrosive air attack, the mirrored side being exposed to the air.
The danger is the semi-mirrored area which is thin to the point of being translucent.......but......
.... wait, Yay!.. I have a dead donor Samyang GX10 which is no use to me.......... I will clean it's mirror (gently) and let you know the result.....
.....however, I'm not sure if the mirror.......... is species sensitive!