If you live in an old house, you have plaster on your walls. You have to use best professional stud finder for this. Here are some tips.
1. When hanging a picture frame from a hook with a nail in it, first tape a large piece of masking tape over the area where you will drive the nail. This will help prevent chip-out. Once the nail is in place, remove the tape.
2. Another way to insert a wall hanger for a picture frame is to drill a small hole for the nail. The hole need not be deep. Just deep enough to penetrate the top coat of plaster. If you see brown dust coming from the drill bit, you are through the topcoat and into the brown coat. To drive a screw through plaster, always drill a pilot hole.
3. Never use a drywall screw in plaster to hold anything. Even it may seem that the plaster is holding it in place, you risk tearing out a large chunk of plaster should you find a weak spot. Always screw through the plaster and into the studs.
4. When screwing through plaster and into the wall studs, make sure you are into the wall studs and not the wood lath that holds the plaster on the wall! Pulling down lath is one of the worst things you can do, as it will pull down large chunks of plaster with it.
5. Standard stud finders don’t work on plaster walls. You need stud sensors that feature some sort of deep penetrating technology. Common stud finders are designed for half-inch drywall walls and can distinguish plaster thickness very well.
6. Use the tapping technique to find studs. Plaster has good techniques and by tapping or rapping it with your knuckles, you can usually hear the hollows between the studs fairly easily.
7. Like anything else in an old house, be careful.There is no guarantee that your wall studs are evenly spaced, that there aren’t old pipes in the walls, or that abandoned and antiquated plumbing and electrical lines exist in the walls.