Ever felt like American houses are made entirely out of cardboard? Compared to Old-Europe style buildings that are actually built from real bricks that’s almost true. The stuff most interior walls are from in the US is actually not cardboard but dry wall (also called gypsum board). Behind the drywall, most interior walls are hollow. This can be a problem when trying to mount furniture or decoration to the wall. When using simple screws or expansion anchors your mount will bare no weight at all, the drywall is just to weak and brittle. A better option is to locate one of the wooden beams that support the drywall and use a long wood screw to mount into the beam. If that is not possible, you have to use special drywall anchors. These anchors are stuck through a hole in the drywall and mechanically expand in some way behind it, to provide stable support. There is quite a range of different designs, see here for an overview. I have successfully used ‘Molly Bolts’ to mount various things.
One good aspect about drywalls is that you don’t actually need a drill to make a hole for the anchor, any more or less pointed object will do (given enough patience). The Molly Bolts are designed to be hammered into the wall without drilling, but that didn’t quite work for me. After placing the bolt into the hole, tighten the (included) screw to expand the anchor inside the wall. Stop tightening once you feel increased resistance, otherwise you might twist off the head. Then, remove the screw from the bolt, stick it through the object you want to mount, re-insert into the bolt and tighten (again, not over-tightening).
What if you don’t need your anchor anymore? Say bye bye, you won’t see it again. Being expanded behind the wall, most anchors cannot be removed without opening a big hole. Instead, in the case of Molly Bolts, just keep tightening the screw, the bolt is designed to break at some point. You remove the screw and the head of the bolt and push the rest into the hollow drywall. There it will rest in darkness until the next major earthquake.
Ebi, from Germany / Menlo Park, CA