Painting Outside of House

If we are to paint the outside of a new house, the first thing is to go over it and "stop" the knots and pitchy places. This is done by covering them with a coat of heavy shellac varnish. The tendency is for the pitch in the knot to ooze out and soften the paint and discolor it. The shellac is supposed to stop this, but it does so only very imperfectly; however, there is nothing else to do. This is so serious a difficulty that the late Mr. Masury, a celebrated manufacturer and paint expert, advised leaving the house unpainted, to the weather, for a year; by which time the pitch will be either washed out or hardened. In fact, it is not unusual for the paint applied to houses of southern pine to come off in the course of two or three years (or one year), and then the next paint adheres all right. However, most people insist on having a new house painted immediately, and the best that can be done is to stop the knots and the worst places with shellac. This works better inside than out.

Then the priming coat is to be applied. Consider now what will happen if a coat of good thick paint is put on a clean board. The oil is rapidly absorbed; but the pigment stays on the surface, and having no oil, or little, to bind it, it shortly becomes a dry powder and falls off. To prevent this, the obvious thing is to use less pigment and more oil. Therefore, to make a priming coat, add a gallon of raw oil to a gallon of ordinary paint; a spongy wood, like redwood, may take more oil.

Redwood is a peculiar wood; it is very open and spongy, so much so that it is reputed a comparatively safe building material, because if it takes fire a little water puts the fire out, as it is so readily absorbed by the wood that it ceases to burn. This explains the trouble often encountered in making paint stay on it; it requires more oil in the priming coat than other woods, so that the pores may be filled with oil, and thus a surface be formed for the adhesion of the subsequent coats of paint.

Another very difficult wood to paint is cypress. This is not bad where the grain is straight and uniform, but around knots and burls the grain is filled with pitchy matter which effectually prevents the entrance of the oil of the priming coat. This resistance is not overcome by the addition of turpentine; and such places must be treated as pitchy places in hard pine, by a coat of shellac, which nevertheless is not satisfactory. Probably the only way to get really good results is to leave it exposed to the weather for a year before painting. On inside work the use of shellac is less objectionable, as it is permanent indoors. A priming coat should be used freely; put on all you can; not enough to run, but up to that limit. This coat is to fill the pores of the wood, and it is the most important of all. A gallon of this thin paint will cover about three hundred square feet. When this is dry, go over the surface and faithfully putty up all the nail-holes and other holes. If you put on the putty before the priming coat, it will not stick. Putty will be described elsewhere; it is crowded down hard into the holes with a stiff steel putty-knife.

Then begins the real painting. Most houses are primed with some light color, the basis of which must be either lead or zinc. It is a general not universal, but in the writer's opinion well-founded belief that a mixture of the two is better than either alone. White lead tends to lose part of its oil by weathering, and then the loose pigment not the whole of the paint, but the superficial part comes off as a powder; chalks, as the painters say. Zinc does not do this, but makes a hard coating which tends to crack and peel off; and a mixture of, say, two parts white lead to one part white zinc is more durable than either. This will in many cases be colored by some of the pigments already mentioned. A little black mixed with white makes a pure gray; but a more agreeable gray results from a mixture with this of red, which makes a warmer tone, or blue, which is colder. Black and red make brown; drab and fawn color contain gray with red and yellow. Green is a mixture of blue and yellow, and the pale greens are derived from this by adding it to white; but olive-green contains also an appreciable amount of yellow, more than enough to make a neutral green, and may be darkened with a little black. Orange is yellow with red, and with white this makes buff. Blue with red makes purple, and this with black'gives maroon; a bright red with a little blue is crimson, and red with a little yellow is scarlet. White with a little red is pink. Besides the pure colors for tinting, already described, it is desirable to have a few others; thus, a good yellow ocher is a clear but not bright brownish yellow, and with white gives straw or corn color; burnt umber is deep brown, and with white gives warm or reddish drab tints; raw umber gives yellowish drab.

It is claimed by some undoubtedly expert paint manufacturers that by the addition of certain cheaper materials, as silicates, carbonates, and the like, they can lessen the cost and still maintain the durability, and this is not impossible nor indeed unlikely; but such paints are likely to be less opaque than pure lead and zinc paints, and hence may need an extra coat to get the desired covering power, and this involves more labor. In plain work a man will put on from one to two gallons of paint a day (oftener one than more), so that the cost of labor is always more than that of the paint. If a dark-colored paint is used, this should not contain any lead or zinc, and will be at once more durable and cheaper; but, as a matter of fact, nearly all houses are painted with a light color.

Ready-mixed paints are sold in enormous quantities, and are no doubt more convenient, uniform, and better made than those mixed by hand. If they are made of good materials and by intelligent men they are in every way desirable. Such paints should be used strictly according to directions.

Nothing is more objectionable than indiscriminate thinning of paint with turpentine or benzine, and nothing is more commonly done. Paint should, before using, be thoroughly stirred up from the bottom, and it will be no harm to strain it through two thicknesses of cheesecloth. Most experts advise that to the first coat of paint which is applied over the priming coat, from half a pint in hot weather to a pint in cool weather of turpentine be added to each gallon of paint; this is to prevent gloss and enable the next coat to adhere well. For the last coat use no turpentine; the more gloss it has, the longer it will wear.

A thin coat of paint will dry through more quickly than a thick one, and most paint manufacturers advise the application of thin coats. There is no doubt that a given amount of paint applied in thin coats is better than the same amount flowed on in thick coats. On the other hand, it is not usual to apply more than two coats over the priming coat, and if these are too thin and they are often made so, not so much by excessive brushing as by thinning before use they do not give proper protection. The late John W. Masury, the greatest paint-man of his time, advocated flowing on full, heavy coats. Mr. Houston Lowe, a manufacturer and undoubtedly a high authority, classifies pigments as active and inactive to linseed oil, and believes that active paints, like lead and zinc, are best in thin coats, and inactive, like iron oxides, etc., are better in thick, heavy coats.

More time must be allowed between coats if they are thick; never less than a week; two weeks is better, a month still better. Painting is best done in moderately warm weather, not below 50 degrees F., better at 70 degrees F.; in cold weather more time must be allowed for it to dry, and less uniform results are obtainable. It must be done in dry weather. Heavy coats in cold weather wrinkle and do all sorts of bad things. A gallon of paint ordinarily covers about 500 to 600 square feet one coat; it may be brushed out to cover nearly twice that surface, but I do not approve of such thin coats. Some do.

The door and window-casings, corner boards, and the like, are collectively called the "trim"; the majority of painters do not paint these until they have laid on the body color, but some good painters advise painting the trim first. Of course the cornice is always painted first of all, as paint may drip from the brush on the wall below. The trim, which is usually painted a different color or shade, amounts, on an ordinary house, to one-fourth or one-third the whole; it should be carefully estimated beforehand. A good man will cover 800 square feet in ten hours, if painting from a ladder;, 1100 to 1500 square feet if painting from a platform; but on intricate surfaces, like piazzas, very much less. Some painters regard these figures as rather high; there are great differences in houses.

Wall-shingles are sometimes, but not usually, painted; they are often colored with a shingle-stain, which is a coloring matter dissolved or suspended in a volatile liquid called creosote, in which the shingles are dipped. Roof-shingles are sometimes dipped in linseed oil and allowed to dry before using. Tin or other metal roofs are difficult to paint, because the tin has an imperceptible coating of grease, or of some chemical substance used in its manufacture, which prevents the adhesion of paint; if this is removed by thoroughly scrubbing the surface with soap and water, or with coarse cloths wet with benzine, the paint will then adhere.

Galvanized iron rain-spouts and gutters are to be treated the same way, otherwise paint will not stick to galvanized iron until it has been some time in use. Roof paint should contain no turpentine and little or no drier, and should be rich in oil. "Fireproof paint", sometimes used on shingle roofs, is made by adding to a gallon of any good paint about a pound of powdered boracic acid. This is not really fire-proof, but retards the spread of fire; the heat fuses the boracic acid to a sort of glass, which keeps out the air. It is of no value until it gets thoroughly dry, and in the course of a year or two the acid is washed out by the rain; for a time it has considerable effect.

Canvas roofs and floors are made thus: the canvas is nailed down, avoiding any large wrinkles, but paying no attention to small ones. Then wet it thoroughly with water; the cloth will shrink and be perfectly smooth. It is customary to apply white lead paint while still wet; but it may be allowed to dry before painting, as the wrinkles do not come back.

As to paints not based on lead or zinc, they are dark in color, made with inert pigments, and are usually very durable, more so than the lead and zinc paints. The following suggestion may be considered properly in connection with exterior painting: in building a house, the door and window frames should receive a coat of paint, which may be a cheap iron oxide paint, on their inner surfaces, that is, on the surfaces which will be concealed in the subsequent construction. This will have great effect in preventing decay, and should always be done. The under side of piazza floors and door-steps should be similarly protected. Exterior varnishing, as of railings, will be considered with the general subject of varnishing.

Next Page: Painting Metal.