I read a long time ago that putting something flat against the mirror will show you. I think if the mirror is legit you’ll see the reflection directly on the surface, if it’s two way the reflection will look like it’s inside the glass.
But I’ve never had the chance to actually test that, so take it with a grain of salt.
Edit: Turns out this is incorrect; thanks to everyone for educating me!
I read a long time ago that putting something flat against the mirror will show you. I think if the mirror is legit you’ll see the reflection directly on the surface, if it’s two way the reflection will look like it’s inside the glass.
But I’ve never had the chance to actually test that, so take it with a grain of salt.
Edit: Turns out this is incorrect; thanks to everyone for educating me!
scientific use mirrors are front mirrors, the metal is deposited on the outer surface. They are delicate and difficult to clean.
Every household mirror is rear coated, and then painted to protect the metal from oxidation.