What is Safety Backing?
Safety Backing is a clear plastic film which is applied to the back of the mirror. It will not prevent the mirror from being broken.
In the event of the mirror getting broken there is a lower risk of cuts and personal harm from shards of falling glass as these tend to stay attached to the film.

Safety Backing is mandatory if screw holes, clips or corner clips are being used in ANY public place, although it is not required for private dwellings. We would, however, always recommend safety backing in private dwellings too, although this is your choice.

Safety Backing should NEVER be used in conjunction with adhesive, it would adhere to the safety backing rather than the actual back of the mirror. Relying on adhesive on one side of the safety backing film to hold the mirror in position is far from adequate.

Safety backing is used in a few ways, i.e. mirrors on wardrobe doors, framed mirrors with or without backboards and also if the mirror is fitted with a hollow section at the back.

Safety backing gives no protection against edge rot at all, this is caused when mirrors are fitted in damp/moist areas. Firstly, how the edge of the mirror has been processed through a glass machine. Rounded edges are not mirror friendly, flat grind and arriss polish are mirror friendly leaving a clean cut 45 degree front edge and back edge.
Secondly, when the mirror is cleaned with strong detergents, chemical cleaners or even some cream cleaners this could cause rot to the silver.
Always use a non-abrasive, specific glass/mirror cleaner.,