PLASTER-WORK. Plastering is one of the most ancient of handicrafts employed in connection with building operations, the earliest evidence showing that the dwellings of primitive man were erected in a simple fashion with sticks and plastered with mud. Soon a more lasting and sightly material was employed to take the place of mud or slime, and that perfection in the compound ing of plastering materials was approached at a very remote period is proved by the fact that some of the earliest plastering which has remained undisturbed excels in its scientific composition that which is used at the present day. The pyramids in Egypt contain plaster-work executed at least 4,00o years ago (probably much earlier) and yet existing, hard and durable. Indeed the principal tools of the plasterer of that time were practically identical in design, shape and purpose with those used to-day. For their finest work the Egyptians used a plaster made from calcined gypsum just like the plaster of paris of the present time, and their methods of plastering on reeds resemble in every way our "lath, plaster, float and set" work. Hair was introduced to strengthen the "stuff," and the whole finished somewhat under an inch thick. Very early in the history of Greek architecture we find (e.g., at Mycenae) the use of plaster of a fine white lime stucco. The art had reached perfection in Greece more than five centuries be tore Christ, and plaster was frequently used to cover temples externally and internally, in some cases even where the building was of marble. It formed a splendid ground for decorative paint ing, which at this period of Grecian history had reached a very high degree of beauty. The temple of Apollo at Bassae, built of yellow sandstone about 470 B.C., is an excellent example. Pave ments of thick, hard plaster, stained with various pigments, were commonly laid in Greek temples. In England the walls of large houses were formerly plastered above the wainscoting and col oured, while the ornamented plaster ceilings of the time of Henry VIII., Elizabeth and James I., are still the admiration of lovers of the art. Still earlier specimens of the plasterer's skill are extant in the pargeted and ornamented fronts of half-timbered houses.
With regard to the smaller buildings, comprising small dwelling houses and cottages, the general application of plaster is of com paratively late date; for wainscoted walls and boarded ceilings or naked joists alone are frequently found in houses of not more than a century old both in England and on the Continent.
Wood and Metal Lathing.—Wood laths are narrow strips of some straight-grained wood, generally Baltic or American fir, in lengths of from two to four or five feet to suit the distances at which the timbers of a floor or partition are set. Laths are about an inch wide, and are made in three thicknesses ; "single" (i to -kin. thick), "lath and a half" (fin. thick), and "double" (ft to fin. thick). The thicker laths should be used in ceilings, to stand the extra strain, and the thinner variety in vertical work such as partitions, except where the latter will be subjected to rough usage. Laths are nailed with a space of about gin. between them to form a key for the plaster, and they must be nailed so as to break joint in bays three or four feet wide with ends butted one against the other. By breaking the joints of the lathing in this way, the tendency for the plaster to crack along the line of joints is dimin ished and a better key is obtained. Every lath should be nailed at each end and wherever it crosses a joist or stud. All timbers over three inches wide should be counter-lathed, that is, have a fillet or double lath nailed along the centre upon which the laths are then nailed. This is done to preserve a good key for the plaster. Walls liable to damp are sometimes battened and lathed in order to form an air cavity between the damp wall and the plastering.
Lathing of metal, either of wire or in the form of perforated sheets, is extensively used on account of its fire-proof and lasting quality. There are very many kinds of this material made in different designs under various patents. A lathing has been intro duced formed of thin wooden rods wired together at fin. intervals. This can be fixed around curves, and economizes plaster.