Furniture & Woodwork

May I ask what you mean by "safe"? I have regularly worked with degraded mercury amalgam mirror plates. I have recently conserved a 17th century cabinet with liquid mercury all over the cracks and crevices. The mercury will leach out from the degraded and oxidised plating, nothing to stop that happening. This will be accelerated if the mirror plate is against any acidic or corrosive material. Often, mirror plates are backed with an oak board, the acidity of the wood is enough to accelerate the degradation. You can of course try to isolate the plate from any corrosive material with a Melinex or anything similar between the mirror and the back board. Some people have painted the back of mirror plate, but the paint does not adhere and does not stop the mercury finding its way out. You can try to "bag" the back of the mirror, but the mercury will slowly accumulate at the bottom of the mirror / in your bag. The only safe measure is to regularly collect the mercury at the bottom of the plate. As far as I know, there is not much you can do I am afraid. I hope that will help, Best regards, Yannick