When the first coat has commenced to harden, it is scored or scratched nearly through its thick ness xvith 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 le-tore the second coat is put on; but as it takes more labor and time to do this, plasterers seldom wait for the first coat to dry before applying the second. unless the specifications stipulate that 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 plumb, 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 erall• be brought to a true plane by means of the grounds, if the laths are set true and the wall is not too large or without openings. On ceilings. however, there is nothing 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 sereeding, which is done by applying horizontal strips of mortar 6 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 scuffle] coat, and \dine soft are made perfectly straight and out of wind with each 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 corresponding 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 brush and small trowel until the surface becomes hard and polished. In most parts of the United States, however, it is the practice to finish with a thin coat of lime putty. plaster of Paris, and
marble-dust, called a white coat. It is applied much as is the skim coat first described.
\\ 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 applied 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 paste and plaster of Paris is used 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. Sea gliola is a coating applied to walls, columns, etc., to imitate marble. The base or is usually a rich lime mixture containing a large proportion of hair. After this has been set and dried, it is eovered.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-east work or stucco. Rough-cast work consists of two coats of rich lime plaster applied to lathing nailed to the outside sheathing and finished with a semi-fluid mixture of clean. fine gravel. lime, and water, which is east or thrown against the wall. Ex ternal stuceo-work consists of two or three coats of cement and sand plaster applied much as is interior plaster. but usually with the final coat marked with lines to imitate stone masonry and colored with some pigment. Staff is a mix ture of plaster of Paris or lime plaster with water and hemp-tibre, 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 stair.