Under no circumstances, so far as the lasting value of the work is concerned, does the mixture play so important a part as the expending of great care upon the thorough surfacing, working, and finishing of the mortar, pressing it into every crevice provided to receive it, flashing thoroughly every exposed or upper surface provided by the finish, and taking every precaution to work out all pinholes or other defects where water could possibly penetrate the surface. Every care and endeavor is directed to providing a solid, evenly worked, and permanent coating which will, in every possible way, throw off and prevent moisture being admitted into the space back of the plaster coating—that vulnerable portion where its attack is most effectually concealed and most to be dreaded.
The exterior plaster treatment of a cement or concrete wall is a problem that from now on will continue to be of rapidly increasing importance. Here, however, it is but necessary to use the cement as nearly neat as possible, adding lime or a make of white cement in case a brighter surface color is desirable. The problem of the [esthetic
treatment of concrete construction is one that requires separate and particular consideration. Its solution has, as yet, been hardly attempted. Hollow terra-cotta tile is another material that is being modernly used more and more as a structural base to take an exterior plaster surface finish.
The student desiring to obtain a wider knowledge of the intricate subject of exterior plastering, may be referred to several articles pub lished in the 1907 numbers of The Architectural Review, Boston. For a work treating historically and practically of the entire art and craft of plastering—within and without the dwelling—see Mr. William Millar's treatise "Plaster, Plain and Decorative." It would be as well to remember, in consulting the latter volume, that it was issued in 1897, and that the subject is treated from the point of view of an English workman, accustomed to methods and materials somewhat different from those common in American practice.