How do I glue strap hangers to the back of a mirror

[evaedery]

I have a very heavy mirror with no fixings at the back; I have bought strap hangers; what type of product do I use to fix them to the back of the mirror and do I need to use 1 or 2 strap hangers (weight of mirror is 1 kg).
Many thanks

 

[Burnerman]

Is the mirror in a timber frame?
Its usual to fix 2 strap hangers with screws just higher up than half way.
John

 

[calorific]

If the mirror is frameless then you need mirror clips. Gluing strap hangers onto the back of it would be a waste of time since although the glue might well be strong enough (2 part araldite would do it FYI), the coating which covers the glass and silver surface won't be.