115. To paint plaster, the first coat should be of white lead, mixed with linseed oil and a small quantity of litharge, the paint being rather thinner than that used for general purposes, that it may fully enter into the absorbent surface of the plaster. The next coat, also, should be thin, so that the plaster may be thoroughly saturated. As this will be but partially absorbed, the third coat is made much thicker, mixing with it spirits of turpentine, and some of the coloring matter approaching the future tint of the room. The fourth coat should be thicker still, and mixed with equal parts of oil and spirits of turpentine, together with the dry ingredient, sugar of lead, instead of litharge. The color should be much darker than that which is to constitute the finishing coat. All these coats should be laid on with the greatest attention paid to smoothing, and each thoroughly dry before the succeeding coat is applied, besides being well rubbed down with glass paper. The last coat, preceding the flatting, should not, however, for reasons already given, be quite hardened.

116. New Walls

New Walls. It does not appear that any painting in oil can, with serviceable effect, be done on stucco, unless the stucco be dry, in itself, and the walls have stood sufficiently long to have given the brickwork the requisite degree of dryness. Stucco, on furred walls, when prepared with abestos, may be painted much sooner than otherwise. The art of painting stucco, so as to stand well, lies, for the most part, in attention to the following observations. The expansive power of water is such, both in freezing and in evaporation, that when it meets with any foreign body obstructing its escape, as, for instance, oil painting, it immediately assails the obstruction, forming, in so doing, a number of vesicles, or cells, containing an acrid lime water, which forces off layers of plaster, and frequently denudes large sections of wall surface, extremely difficult to cover up. Two or three years are not, in most cases, too long a period for stucco to remain unpainted. In work entered upon for mere purposes of gain, just so many weeks are, however, reluctantly allowed. The merits of some patent liquids are, indeed, so set forth as to claim, in spite of the natural properties of bodies, that stucco, washed over with these nostrums, may be, immediately after, painted with oil colors. Instances may, in fact, be cited, and experiments adduced, which, at first glance, seemingly contradict, but shall, upon investigation, be found to confirm the laws of nature.

These precautions attended to, there is no better material for priming, or applying the first coat, on stucco than linseed or nut oil, boiled with driers, care being taken, in all cases, not to lay it on too thick, nor in larger quantity than the stucco will absorb, rendering the surface rough and irregular. It should then be covered with three or four coats of ceruse, or native carbonate of lead (prepared in the manner set forth for intermediate coats, Art. 108), giving each coat sufficient time to dry hard. If time permit, two or three days between each layer will not be too long. If the stucco be intended for finishing in some given tint, gray, light green, apricot, etc., it will be proper to prepare the ground for the desired tint by a slight advance towards it, about the third coat of paint.