Rawlplugs: How to Use Wall-Plugs
It is often necessary to secure a fitting to a wall with. A cannot be driven into an unprepared brick and plaster wall — at least, not with any degree of permanency — but screws may be driven into the ‘studs’ of lath and plaster walls. Brick and plaster walls sound solid when rapped; lath and plaster walls, used mostly for separating upstairs rooms, sound hollow when rapped.
A stud is the upright support, in a lath and plaster wall, to which the laths are nailed before they are covered with plaster. Most studs are 4 in. by 2 in., placed at intervals of about 12 in. to 15 in. along a wall. A stud can usually be located by inspection of the skirting-board or picture-rail, in which sunken depressions, at about 12-in. to 15-in. intervals, indicate where the picture-rail or skirting-board has been nailed to the studs — find a nail depression and you have found a stud.
Studs may also be located by rapping the wall with the handle of a screwdriver; the position of the stud responds with a duller echo than the spaces between. If a stud cannot be found by position of, or rapping, it may be located by pushing a bradawl into the wall, moving along the wall with 1 in. between insertions of the bradawl until the stud is found. The stud gives firm resistance to the bradawl; spaces between studs offer lesser resistance to the blade of the tool. Once two adjoining studs have been found it becomes a simple matter to measure the space between the studs to mark the positions of all the studs in the wall. Screws may then be driven into the studs with impunity, for shelf brackets, hanging cupboards and fittings of all kinds.
Brick and plaster walls must first be plugged before screws can be driven into them. This is done by cutting a hole into the wall and filling the hole with a fibrous plug. The plug-holes may be bored with a carbon-tipped masonry drill used in an electric-powered drill or hand drill, or the hole may be tapped with a ‘jumper’. A jumper (or ‘star’ chisel as it is sometimes called) is a fluted chisel, fitted into a solid steel handle; it is held in position against the wall and the end of the handle is struck with a hammer. In between each hammer blow the jumper is rotated slightly to make a cleanly cut hole.
The jumper chisel-blades are exchangeable in the handle, and they are available in standardgauge numbers. A number eight jumper (used with a No. 8 screw) will be found to be the most useful general size, other jumper sizes may be added to the handyman’s tool-kit when and as required. The plugs of tubes of compressed fibre are also supplied in standard screw sizes — a number eight plug is used in the same jumper number for No. 8 screws, and so on with other sizes. The sequence of operations is illustrated below: (A) shows the jumper held against the wall, (B) shows a cross-section of the hole cut into the masonry, (C) shows the fibre plug inserted in the hole — note that the hole is slightly longer than the plug. With this done the screw may be driven into the plug to attach any kind of fitment, and will support considerable weights.
An alternative method of plugging embodies the use of a fibre compound in place of the tubular plug. The hole is cut in the usual way; the dry compound, which is obtainable in tins, is mixed with water to the consistency of putty. The putty-like mixture is then tamped into the hole, and the screw is driven into the soft compound, which later hardens to hold the screw firmly in place. Screws may, of course, be removed from both kinds of plugs.