Nearly all that has been said with regard to operations in the building trades is connected with construction, but here we shall speak chiefly of decoration. It has long been found necessary to protect wood and iron from the ill effects of moisture by a hard exterior coating impervious to wet; and hitherto the best preservatives have been found to be paint and varnish, through which no wet can penetrate as long as they remain in a sound state.

In doing work of this kind, it is much better and cheaper to buy paints and varnishes ready mixed. One very good reason why the amateur painter should do this is that the paint which he makes himself is apt to take a long time to get thoroughly dry and hard; and sometimes, even after the lapse of several weeks, it is still sticky.

Before beginning to paint, all dirt and projections, such as lumps of glue, etc., must be cleared away with the putty-knife and duster. Then, if the work be new, all the knots in the wood must be killed with knotting, to prevent the turpentine in the knots from oozing out and spoiling the appearance of the painting when finished. Knotting is a preparation of red lead, litharge, boiled oil, and a little turpentine; the amateur is advised to buy the " patent knotting," which may be obtained ready for use. After the knotting, which dries and hardens very quickly, is applied, the priming, or first coat, is put on. This is made of white lead, with some drying material, and a little red lead to harden it. It is made very thin with oil, as unpainted wood or plaster absorbs the paint very quickly.