Page:The New International Encyclopædia 1st ed. v. 03.djvu/726

* BUILDING. 644 BUILDING. mixed with water to the proper plasticity and immediately applied to the lathing. Xatural-ceineiit jjlasters are made from certain kinds of eartlis found in Kansas and Texas, which assume a pulverized form when calcined, and when mixed with water will set like hydrau- lic lime or cement, but much more slowly, so that ample time is ali'ordcd for applying the plaster. The chemical or patented plasters connnonly used are of a secret composition ; but it is known in a general way that they are com])ounds of gypsum, to which some chemical is added, which has the efl'ect of retarding the naturally quick setting of that material. Plastering on lathing is gen- erally done in three coats, known as the first or scratch coat, the second or brown coat, and the third or white coat, skim coat, or finish. The scratch coat is always made rich, and contains plenty of hair or fibre, since it forms the founda- tion for the brown and finish coats. The scratch coat is generally put on from three-sixteenths to one-quarter inch thick over the laths, and is pressed by the trowel with sufficient force to squeeze it between and behind the laths so as to form a key or clinch. It is this key which holds the plaster to the laths. When the first coat has commenced to harden, it is scored or scratelied nearly through its thick- ness with lines diagonally across each other and about two or three inches apart. This scratch- ing gives a better hold to the second coat. Pref- erably the first coat should be thoroughly dry before the second coat is put on: bit as it tiikes more labor and time to do this, plasterers seldom wait for the first coat to dry before applying the second, unless the specifications stipulate lliat they must. The second, or brown coat, is put on from one-quarter inch to three-quarters inch thick; with this coat all surfaces should be brought to a true plane, the angles made straight, the walls pUnnb, and the ceilings level. This tru- ing up and leveling of the work is the most par- ticular and difficult task that confronts the plasterer. On the walls the plastering can gen- erally be brought to a true plane by means of tlio grounds, if the laths are set true and the wall is not too large or without openings. On ceilings, however, there is usually nolliing to guide the plasterer in his work ; and the consequence is, that most ceilings, particularly in domestic work, have 'rolling* surfaces. The only way of obtain- ing a true plane on ceilings and on walls where the grounds are not sufficient is by screeding, which is done by applying horizontal strips of mortar G or S inches wide and from 2 to 3 feet apart all around the room. These are made to project from the first coat out to the intended face of the second coat, and while soft are made perfectly straight and out of wind with cacli other by measuring with a plumb, straight edge, etc. When the screeds are dry. the second coat is put on. filling up the broad horizontal spaces between them, and is readily brought to a per- fectly flat surface corres]jonding with the screeds by long straight edges extending over their sur- face. Screeding is expensive work, and is seldom practiced except in the most costly buildings. The finishing coat differs somewhat in different localities. In many of the Eastern States this coat is called the skim coat, and is made of lime putty and fine white sand. It is put on with a trowel, floated down, and then gone over with a bi-ush and small trowel until the surface becomes hard and polished. In most parts of the United States, however, it is the praeiice to finish with a thin coat of lime putty, plaster of Paris, and marble-dust. caHed a white coat. It is applied much as is the skim coat first described. W hen a rough finish is desired, a sand coat con- sisting of lime putty and coarse sand is used. The preceding description applies particularly to the laying of lime plaster, but the hard-wall plasters are apjilied in almost the same man- ner. Stucco-work is ornamental interior plaster- work, such as cornices, moldings, and centre- pieces. For such work a mixture of lime ])aste and plaster of Paris is use<l except for cast-work, which is made entirely of plaster of Paris. Plain moldings of all kinds are usually 'run' in place by hand. The process consists in placing on the surface of the wall or ceiling a sufficient body of plaster and forming the molding by running along it a sheet-iron template cut to the re- verse profile of the molding. Stucco-work is al- ways done before the finishing coat of plaster- ing is applied. If the cornice or molding con- tains much ornamental work it is usually cast in molds in about two-foot lengths and cemented in place with a wash of plaster of Paris. Sca- ijliola is a coating applied to walls, columns, etc., to imitate marble. The base or groundwork is usually a rich lime mixture containing a large proportion of hair. After this has been set and dried, it is covered_with a coat of plaster of Paris or Kane's cement mixed with various coloring matters in a solution of glue or isinglass. When thoroughly dry, this coat is rubbed with pumice- stone and carefully polished. External plaster- ing is usually either rough-cast work or stucco. Rough-cast work consists of two coats of rich lime plaster applied to lathing nailed to the outside sheatliing and finished with a semi-lluid mixture of clean, fine gravel, lime, and water, which is cast or thrown against the wall. E.x- tcrnal stucco-work consists of two or three coats of cement and sand plaster ap|)lied much as is interior plaster, but usually with the final coat marked with lines to imitate stone masonry and colored w'ith some pigment. Staff is a mix- ture of plaster of Paris or lime plaster with water and liemp-fibre, which is cast in molds into blocks, slabs, and trimmings of all sorts, and fastened by nails to wooden frames and boarding. The great majority of modern exhibition build- ings have been made of staff. C.VKPKNTRY is the process of cutting, framing, and joining the timbers of buildings by means of band-tools. In building work, it includes the framing of the main structural skeleton or framework, covering it with rough boarding, clapboards, .shingles, etc., the construction of windows and door-frames and of cornices, gutters, etc. Interior woodwork is here classed as joinery; but the distinction between the two processes is not sharply defined in practice, and in America ("irjienters erect the interior woodwork as well as otlicr parts. In modern building jiractice wooden buiklings are framed in three ways. Previous to 1830 the braced or full frame was alone used. In this method of framing the sills, girts, posts, and plates are made of heavy timbers, and are all mortised and ]iinned together. Braces are mor- tised and pinned to post, sill, and girt, and stud- ding is mortised and jiinned to sills, girts, and plates. To frame a building in this way, it is necessary to cut all the pieces and make all the