Another one of the causes of failure of lead and zinc paints for exterior work suggested by some authorities is the use of volatile thinners like turpentine and benzine. They say that such thinners should not be permitted on the job, for they are a temptation to the painter. If raw linseed-oil is used, and it is necessary to shorten the time required for drying, some good drier should be added, say 5 per cent. This drier should be pale in color and free from rosin. Driers are usually made of oil combined with a good proportion of lead and a little of manganese.
White pine, Douglas fir, yellow pine, cypress, or any of these woods, usually contain some knots, which are sure to damage exterior white paint unless properly treated. These knots have a certain amount of pitch in them, which will penetrate through any oil paint and leave an ugly mark. They should be covered with shellac, which is not affected by the pitch. Shellac is a spirit varnish made from shellac resins dissolved in alcohol. The yellow shellac is the strongest, but the white is used where a light-colored paint is to be applied on top of it. The pitch which is so bad in knots is often distributed throughout the wood, as in Southern yellow pine, and this will often cause the paint to peel off. To prevent this to a certain extent, some specifications advise using benzol in the priming coat, in order to make the paint penetrate more deeply into the wood and get a better grip on the surface.
The priming coat of any painting job should either be pure linseed-oil or linseed-oil with very little pigment in it. Its purpose is to fill the pores of the wood before the other coats are applied, for if an ordinary thick coat of paint were applied to raw wood, the surface would draw so much oil out of the film of paint that most of the pigment would be left dry and unfastened upon the outside.
Only after the wood has been given the priming coat is it then time to putty up the nail holes and other defects, and not before, because the dry wood, as in the case of paint, will suck out the oil from the putty and leave it without anything to bind it together. The best putty for this work is made of linseed-oil with enough white-lead in it to make a thick paste. The putty which is commonly used, however, is made of whiting or ground chalk mixed with linseed-oil. This is durable if real linseed-oil is used, but often some inferior adulterant is substituted.
After the holes are all puttied, the other coats of paint may be added. At least two good coats should be applied, and three coats give superior results. Plenty of time should be allowed between coats to permit thorough drying of the previous one.
XVI
LABOR-SAVING DEVICES FOR THE HOME
The Demand
The need for labor-saving devices to help in housekeeping is more evident in the small house than in the larger house, although the cost of such machinery often prevents its installation in the former, whereas in the latter it is more to be found, since the person who builds a large house is apt to have more funds to draw upon. Yet labor-saving devices really belong to the small house, for the large house is still run by the servant, but the small one is kept by the lady of the house. She rightly objects to working in the old-style kitchen, which was very large and ugly, and the useless up-keep of many rooms that are really not needed is not to her liking, so that in practice the small house is in a way a labor-saving device in itself, since it reduces the amount of house to be kept, and makes the kitchen small and attractive. Then, frankly, labor-saving machinery is more becoming to this house, which is in itself designed to save labor, and money wisely spent upon such devices is by no means out of proportion to the cost of construction, even if in direct comparison it shows a larger percentage ratio to the building cost in the small house than in the large house.