Plastering. With the completion of the lathing the house will be ready for the plasterer. Already the mortar will have been mixed, and, piled in large stacks, should have been standing for a week or more. The sand and lime having passed the same scrutiny and tests which we employed when making the mortar for the. mason-work, the only thing necessary will be to see that the mortar is well mixed and tempered and that hair of the proper amount and quality is added at the proper time.
Mixing. For the best result the lime should be thoroughly slaked at least twenty-four hours before adding the hair, which must be thoroughly beaten up and mixed with the lime paste with a hoe, and the necessary amount of sand added. This mixture should then be stacked outside of the building as long as possible before being used, in our case at least ten days. When ready for applying small quantities of this mixture are wet up with water to the proper consistency, tempering, this is called. Unless particular care is taken the sand and hair will be added as soon as the lime is slaked as it is much more convenient to do; but this should not be allowed as the lime does not always get wholly slaked and the steam and heat of the slaking lime will burn the hair and destroy its strength.
Another practice which should he avoided, is that of mixing the mortar in the basement of the building as the steam and moisture will penetrate to all parts of the building at a time when the imme diate application of the plastering gives no opportunity for drying off. In regard to the proportions, about one and one-half bushels of hair and three barrels of sand to a cask of lime is a good ratio, but the amount of sand will in ordinary cases be determined by the judg ment of the mixer, who should be a competent and experienced nian.
applying the Mortar. IVhen the mortar is ready for putting on the laths, we must see that the first or scratch coat is well trowelled to push it through the spaces between the laths so as to form a good key. In ordinary two-coat work this first coat is put on thick enough to come within an eighth of an inch or less of the face of the grounds and beads, as the finish or skim coat is merely a thin veneer of lime putty and fine white sand, trowelled and brushed to a hart] surface. In three-coat work, the first coat is put on about one-quarter of an inch thick and when somewhat hard it is scratched with diagonal lines nearly through to the laths. As soon as this coat is dry, the second coat is applied and brought to a plane with all angles and corners true and plumb. On large surfaces or important work this is best clone by running "screeds", which are strips of mortar six to eight inches wide and three or four feet apart, carefully laid and levelled and plumbed with corners and angles made true and brought to the line of the second coat, which is filled in between these upon the scratch coat and brought to a line by running straight edges from screed to screed. Upon this second coat is applied the third or finishing coat, usually either the skim coat as upon two-coat work, or a "white-coat" which is made by mixing plaster of Paris and marble dust with the lime putty. If a rougher finish is desired, as
for frescoing, a coarse sand in greater quantities may be mixed with the lime putty and floated with a pine or cork-faced float. By con sulting the specifications we find that this finish is called for in two coat work to be left "medium rough." Screens. Before the plastering is begun the windows must be closed in with screens made of cotton cloth tacked upon wooden frames, made to fit the window frames. These are not only to protect the plastering from freezing, by which ordinary lime mortar is com pletely ruined, but also to prevent unequal drying of the finished walls which will occur near the windows in good breezy weather.
Exterior Plastering. The plastering of exterior walls is done to a large extent in Canada and the British possessions and is used to increasing extent in the United States. This is best done over matched boarding by furring off with seven-eighths inch strips and using wire or other metal lathing which later events have shown is better if galvanized or painted. The plastering should be three-coat work, with one-third of Portland cement for all three coats, the last having the coarse sand or gravel if a rough finish is desired. If metal lathing is not easily procured a good result is obtained by lathing upon the boarding diagonally in one-and-one-half inch spaces and repeating the lathing diagonally in the opposite direction, all well nailed and secure. Upon this we may plaster as upon the metal lathing.
Concreting. When the last of the plastering has been com pleted the concreting of the cellar should be begun so that it may be drying out with the plastering. For this the best cement must be used, mixed in the proportion of one shovelful of cement to three of sand well mixed, and to this added five shovelfuls of screeped peb bles or broken stone, this should be at once spread upon the floor and paddled and trowelled to a perfectly level surface, the whole topped, when hard enough, with one-half inch of fat Portland cement mortar.
Fireplaces. While the plastering and concreting are drying out the finished fireplaces are usually built. These are to be of bricks and should be built with a splay of from six to eight inches to the sides. (See Fig. 34.) The back lining is built up for about six courses and then inclined toward the front until an opening of only about two inches is left. (Fig. 42.) If a flat arch or level bricks are used for the opening there must be provided a wrought iron bar, or better, two bars which must be let up into the under side of the bricks so as not to be seen. Care must be taken to see that fireplaces are set in the exact center of chimney breasts and rooms, and also that the face of the bricks are set in the required position, usually flush with the plaster line, al though this may be varied to allow for differences in the form of mantel desired.