If you're putting up heavy pictures or shelving, the safest way to hang them is from the wall studs. But how do you find a good, strong stud?
You could do the old tap-tap-tap method listening for hollow and solid sounds, which is not a very precise method. Or use an old-style stud finder that uses the simple magnet principle - you run the magnet in the stud finder against a wall until it goes over a nail in the stud, then the magnet goes horizontal. This works fine if you happen upon nails regularly and if the nails are in the center of stud; if they're not centered, you could be nailing into the end of the stud. But the new electronic stud sensors make the tapping and magnetic stud finders obsolete.
Using density sensors, the new version is a faster, more accurate way to find studs and it gives you a better sense of the stud's width. These new, high-tech gadgets beep or light up when the material behind your plasterboard goes from airy (insulation) to solid (wood). It's a smart investment that will end up saving you time and aggravation.
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