Pulverized oxides of iron, such as yellow and red iron ochres, or brown hematite iron ores, finely ground, and simply mixed with linseed oil and a dryer.
White lead applied directly to iron is thought to have a corrosive effect. It may be applied over more durable colors.
Red lead, when pure, is very durable. An instance is recorded of iron painted with it having been under water for nearly 50 years, and had not been affected by rust.
Sheet iron, before being used for roofs or other outside purposes, should be heated and dipped into hot linseed oil, which will penetrate into it. Tinned iron in roofs has been found to corrode quicker than in former years, owing to the more general use of coal.
Paint for Rusty Iron.—Black Japan varnish, mixed with turpentine, to make it thinner if necessary, is one of the best preventatives; but the iron must be dry when you put it on. If you can warm the iron when painting it, so much the better. If not sufficiently opaque, you may put in dry finely pulverized paint, such as lamp-black. Red lead, with linseed oil is also a good paint for rusted iron; so are the mineral reddish-browns which consist of oxide of iron; they become very hard, and are used for the iron-work of the elevated railroads in this city.
To Paint on Stucco.—Great care is required in painting upon stucco, for the work must not only be thoroughly dry, but free from any liability of dampness; that is to say, the walls themselves must be dry. It is, consequently, usual to allow the stucco to remain for several months before it is painted; and this is especially necessary when it covers over a large surface, as in the walls of churches, chapels and theatres. If the paint be applied too soon, the work will have a blotched appearance, and be probably filled with small vesicles, formed during the evaporation of the water. When the work is dry, it may be prepared by covering it with a coat of linseed oil, boiled with dryer. This must be laid on very carefully, or the face will be irregular. The color may then be applied, and four coats will not be too much, the work being new. Persons are generally so anxious to have their buildings finished, that they disregard the future appearance of the work, and within a few weeks after the application of the stucco, cover it with paint. But it would, in all cases, be sufficient to wash the surface with distemper, as it would give a finished appearance to the building, and make it less necessary to hurry the work. When the work is sufficiently dry to receive the oil-colors the distemper color should be removed by washing, and when the stucco is dry apply the oil-color. The tints may be regulated by mingling different colors, as in all other kinds of painting.
Plastered walls should not be painted until they are thoroughly dry, and all settling in a new house has taken place. If painted too soon they will blister.
Unseasoned wood should never be painted, as it stops the pores of the wood and the sap acidulates, causing dry rot. Greasy surfaces must be washed with water mixed with lime or soda, otherwise the paint will not adhere to it.
Mixing Quick Drying Paint.—Venetian blinds should be painted to dry dead, then varnish; but few take this trouble. Mix the paint as under: White lead, boiled oil, and the least drop of turps; mix sufficient of each to form a creamy mixture; then add about 1 oz. patent drier to each 1 lb. of paint. If you want the paint darker use enough burnt umber to give the required tint. If you want to varnish, omit the oil and use turps.
Transparent Paint for Glass.—Take for blue pigment, Prussian blue; for red, crimson lake; for yellow, Indian yellow; and for other shades, a mixture of the appropriate primary colors. Rub them in a size made as follows: Venice turpentine, 2 parts; spirits of turpentine, 1 part, and apply with a brush. The colors are moderately fast unless exposed too long to direct sunlight. A solution of the various aniline dyes in shellac varnish has also been recommended.