This section is from the book "A Treatise On Architecture And Building Construction Vol2: Masonry. Carpentry. Joinery", by The Colliery Engineer Co. Also available from Amazon: A Treatise On Architecture And Building Construction.
247. The term stucco was first used by the early Italian artificers to define a superior grade of plaster compounded by them; and their skilful manipulation of the material has never been excelled. From the fact that the appearance of dignity and stateliness could be acquired by its use, on an otherwise mean and poverty-stricken erection, at a very low price, it was for many centuries most extensively used. Many of the so called stone and marble palaces will be found on examination to be but brick shells, coated or veneered with stucco, so well treated and handled as to present a very superior surface, scarcely discernible from the material that it is made to imitate. At the present time, stucco is used only to a limited extent, and only for a cheap class of structures.
To secure the best results in stucco work, a good cement mortar is requisite, as lime mortar, which was formerly used, does not prove very durable. For use on brickwork, the plaster should be made of Portland cement and clean, sharp sand, mixed in the proportion of 1 part of cement to 3 parts of sand, with sufficient water to make a stiff paste. Before adding the water, the mortar joints in the brickwork should be raked out, so as to form a good clinch for the covering, and the surface of the wall should be well dampened, to prevent the brick from too quickly absorbing the water in the mortar. Resort is sometimes had to screeding, to make the surface true and uniform. When the mortar is put on in more than one layer, the previously laid coat should not be allowed to dry before the next one is applied, else the coats will not adhere well, and will probably scale off. Before the finishing coat has hardened, it may be marked with lines to imitate the joints in ashlar. The mortar may be colored to represent stone by use of mineral colors, such as Venetian red or the ochers; while, if a light color is desired, it may be obtained by mixing a small quantity of lime with the cement.
248. Rough east is a kind of coarse plastering considerably used in Canada and other cold climates, as a substitute for siding and shingles; it costs less, is more durable and much warmer than wood, and resists fire to a considerable extent. If a frame building is to be covered, it should first be stiffened by having the partitions built and the outside sheathing put on. On the latter are then nailed laths, laid diagonally and about 11/2 inches apart, breaking joint about every 18 inches. Over this course is laid another, the laths sloping in the opposite direction, with similar spacing and broken joints. This thickness of lathing should be put on with great care, to insure the permanence of the work; if wire or expanded metal lathing is used, there will be considerable gain in strength and fireproof qualities. The scratch coat should be made of rich lime mortar having a large proportion of hair, and should be mixed about four days before it is applied. This coat should be thoroughly laid on and well pressed between the laths, to form a good clinch, and the surface should be well scratched to form a key for the second coat. It must be allowed to dry thoroughly, but its surface should be sprinkled before applying the second coat, which has the same composition as the first. This should be kept moist and soft until the finishing coat is put on. The latter is called the dash, and is made of clean, fine gravel and lime stirred up with water until the mass has a semifluid consistency; various coloring matters may be added, if required. A black mortar may be obtained by mixing 5 pounds of lampblack with the dash; a buff, by using a like weight of copperas. The dash is then thrown upon the plastered walls with a wooden float about 5 or 6 inches square; before it dries, it is gone over with a brush dipped in the liquid, to give the face a uniform appearance.
For 100 square yards, applied as above described, there will be needed 1,800 laths, 16 pounds of 1 1/4-inch lath nails, 12 bushels lime, 1 1/2 barrels hair, 1 3/4 cubic yards of sand, and 3/4 cubic yard washed gravel. For the dash, a quarter barrel of lime putty should be mixed with every barrel of washed gravel.
249. Staff was first brought into extensive use, in this country, in the construction of the World's Fair buildings in Chicago in 1891-93, although it has been used for a long period in Europe. As used in Chicago, it is made about as follows: The ingredients are plaster of Paris, water, and hemp fiber, the latter being used to bind and strengthen the cast. A suitable mold having been made, the hemp is cut into pieces about 6 or 8 inches long, bunched loosely, dipped in the liquid, and placed in the mold in layers until the mold is full, each handful being interwoven with those previously laid, and pressed in so that the cast will be compact and uniform throughout. When the mold is filled, the surface is smoothed over by hand, and the cast is removed when set. About 36 hours are necessary for thorough drying, in warm weather; in winter, more time is required, and the cast should not be subjected to frost before it is dry.
Staff may be nailed directly to the rough boarding of a wooden building; if it is to be applied to a new brick structure, furring strips should be inserted in the brickwork.
This material, while cheap and satisfactory for temporary structures, does not seem well adapted for permanent buildings, as it deteriorates in course of time in the Northern states, owing to the rapid changes of temperature. Where the temperature is more uniform, staff has proved to be a very durable material.