I’ve been reflecting on a problem. What I’ve got here is a heavy mirror and an old plaster wall--75 years old. Now what’s the most secure way to hang this? In this case, the original hanging hardware has to go, so I remove it. Then I measure an equal distance down both sides, drill pilot holes and attach hanger straps using short screws. Braided picture wire is looped through the straps and twisted back upon itself. The next step is to draw a level line on the wall where the top of the frame will be. I stretch the hanging wire taught and measure the distance between the wire and the top of the frame. That’s the distance below the level line I just drew that I am going to place the wall hangers.
Toggle bolts are usually the best way to hang heavy objects on plaster walls. The spring-loaded wings of the toggle bolt fold together. Once inside, the wings spring open. I’ll drill a hole large enough to allow the folded wings to pass through. A piece of masking tape helps keep the plaster from cracking or chipping. Finally, I pull gently on the bolt as I tighten it, which will keep the toggle from spinning inside the wall. With both toggle bolts tightened firmly, it’s time to hang the mirror. You just hoist this up here, put it on the hooks, make sure you catch both of them, slide it back and forth a little bit to make sure it’s level. Now the beauty of a two-hook system is that once you get it level, it stays level.