“First-surface” mirrors where the reflective layer is on the front of the glass are quite fragile, so wouldn’t typically used for residential applications (you’d remove the reflective coating by cleaning it).
A regular mirror has the reflective surface on the back of the glass (which is then is further coated with a protective paint), leading to the effect you describe.
I don’t however know enough to say one way or the other whether a surveillance mirror would becessarily be a first-surface mirror.
It would be the other way around, if at all.
“First-surface” mirrors where the reflective layer is on the front of the glass are quite fragile, so wouldn’t typically used for residential applications (you’d remove the reflective coating by cleaning it).
A regular mirror has the reflective surface on the back of the glass (which is then is further coated with a protective paint), leading to the effect you describe.
I don’t however know enough to say one way or the other whether a surveillance mirror would becessarily be a first-surface mirror.
Just checked my bathroom mirror and it looks to be a first-surface mirror