Anchor screws are used for hanging light- to semi-heavy objects on a wall, such as a large mirror, wall shelf, or mirror. Screw anchors are helpful because they allow you to hang items virtually anywhere, without hunting for a stud to sink the screw into. The other great advantage of screw anchors is flexibility: you are not bound to the rigid spacing of studs, typically 16 inches on-center.

How to Install Screw Anchors

Light products are often sold with the screws and plastic sleeves already in the pack. Medium-heavy objects, such as mirrors and or shelving, should be hung using toggle bolts.

If the object being hung is especially fragile or valuable, consider purchasing heavy-duty wall screws, such as Toggler SnapSkrus (buy on Amazon). These self-piloting sleeves come with their own screws and hold up to 65 pounds each in drywall. While fairly expensive, SnapSkrus provide a more stable anchor than the push-in plastic sleeve anchors that are provided for free with some products.

But if the item is fairly light and isn’t especially valuable, the plastic sleeve anchor screws work fine because they still have a good degree of shear strength.

Get the Weight Right

When anchor screws fail, it is often because the installer did not correctly assess the weight of the object. Determine the weight of the object with a scale or by consulting the packaging. Purchase the appropriate anchor and screw sets. The label on the box will indicate the maximum weight that the anchor and screw set will support.

Generally speaking, pictures and objects with a total weight of 15 pounds or less can be hung using plastic screws and sleeve anchors or metal threaded drywall anchors. Mirrors and pictures with glass are both very heavy and will require the sturdiest anchors you can buy.

Use a Drill to Make the Hole

It is tempting to make the initial hole with a nail since this makes less of a mess than drilling. But a drill is needed to core out sufficient space for the anchor sleeve.

The drill bit should be a little smaller than the closed end of the anchor. If the bit is too big, the anchor will not fit snugly inside of the hole. Drill gently in the center of the pencil mark. Brush the dust from the area.

A good rule of thumb is to make the hole smaller than you think it should be. If it proves to be too small, you can always enlarge it. But if it is too large, there is no way to reduce its size. The only option at that point is to drill another hole elsewhere.

Tap It the Rest of the Way and Add the Screw

The fit must be tight enough that it takes some gentle tapping to get it in. But if it is too tight, the sleeve will warp. Gently tap the plastic anchor into the wall using a hammer or rubber mallet.

Insert the screw into the anchor and slowly screw it in. If using a threaded drywall anchor, screw it in using a Phillips head screwdriver. If using a toggle anchor, thread the toggle on the screw about 1/4 inch from the end. Push the toggle through the hole in the wall. The toggle will make a snapping sound when it springs open on the other side of the wall. Tighten the screw until snug, but do not tighten too much or you risk damaging the drywall.

How to Remove Screw Anchors

Almost as important as installing screw anchors is how to remove them without damaging your wall. You have two methods at your disposal. If the first method proves to be too difficult, move to the next method.

Removing the Screw and Anchor Sleeve

1. Turn out the screw and discard it.
2. Gently pry up the visible end of the sleeve with a flat head screwdriver so that you can grab it with needle-nose pliers.
3. Use the pliers to pull the sleeve straight out.

Tap and Cover Rather Than Remove

When wall anchors become impossible to remove without damaging the drywall, the best thing to do is to tap it further into the wall and cover, then paint.

1. Place a large Phillips screwdriver on the end of the anchor.
2. Gently tap with a hammer until the anchor sinks below the surface of the drywall. You do not need to go far.
3. Cover drywall compound and paint over it.

via: https://www.thespruce.com/how-to-use-and-discard-anchor-screws-1822671