In the case of close-grained woods, the paste filler is unnecessary. First give the floor a coat of linseed oil, using about one quart of turpen tine and from one-half pint to one pint of best liquid driers to the gallon of oil. Rub this oil well into the wood, and next day it will be ready for the shellac. This darkens the wood a little, but it is almost impossible to do a good job of shellacking on bare boards. There is so much adulterated shellac on the market that is dear at any price, that it is economy to buy only from a responsible firm and to pay a good price to get a pure shellac cut with denatured alcohol.
Instead of using wax, the floor may be kept in good condition by giving it repeated coats of a non-drying mineral oil—one of the so-called polishing oils or floor oils. This should be well rubbed into the floor, and wiped off with a dry rag so as to leave no surplus oil on the surface. A. hard pine floor may be brought up this way from the beginning, using neither filler nor shellac. It can readily be kept in condition by the housewife, wiping up the floor about once a week with a rag barely moistened with the oil, and rubbing it with a dry rag. Some of these floor oils contain a very little wax, which may be of some advantage.
In the case of spruce floors which may be in poor condition, if it is desired to use rugs, and at the same time not spend any more on the floors than is absolutely necessary, use a good brand of liquid filler made with a pigment base, adding burnt umber and a little burnt sienna to get the desired shade. After this has dried for two days, a coat of floor varnish is given. See that the floors are regularly treated with polishing oil every week or ten days. Any floor varnish will, in time, mar white under ordinary conditions; nevertheless a var nished floor may be kept in good condition indefinitely, if it is regularly oiled.
Some people recommend the use of boiled linseed oil and driers for keeping floors in con dition. While it is true that good results can be obtained by using this treatment on the bare wood or over varnish, and continuing it regu larly, there is a danger connected with it which cannot be too strongly emphasized. This mix ture is a very powerful oxidizing agent; and if a bundle of cotton waste or cotton rags soaked in it is carelessly thrown into a closet or left in a corner, spontaneous combustion will almost inevitably follow within a few hours. The only safe plan to pursue is to burn the waste or rags immediately after the oiling is done. Many an unexplained fire has resulted from carelessness on the part of servants neglecting this simple precaution. It is far better to avoid the risk by using the non-drying mineral oil, rather than the boiled linseed oil.
Wood Fillers and Surfacers. Much of the beauty and durability of the finished varnish surface will depend upon the selection and proper use of a class of materials known as wood fillers and surfacers or first-coaters.
For the preparation of all open-grained woods, such as oak, chestnut, ash, and the like, in all cases where a smooth surface is desired, it is necessary to fill up the open grain of the wood with a hard, transparent substance, which should not be acted upon by the tannin or tannic acid contained in wood of this character, and which should be chemically inert in regard to the varnish that is to be applied upon it.
If varnish were coated directly upon one of these open-grained woods it would sink down into the inequalities and would give a surface far from level, and even several subsequent coatings would still show traces of this inequal ity. It is true that it might be possible to pro duce a perfect finish by means of varnish alone, provided much labor were used in rubbing down these irregularities with pumice, but this would be a tedious and expensive means of obtaining an end that is more directly reached by the use of a paste wood filler. This will give a smooth, hard, and glassy surface to which the subse quent coats of varnish will adhere firmly, and upon which they can be made to lie in smooth, even films that will take but comparatively little labor to rub to a practically perfect surface, and upon which a high polish can be produced.
A paste filler might correctly be termed a paint, inasmuch as it is composed of a solid substance held in suspension by a liquid or vehicle. Paste fillers of all sorts have been put on the market, and many different materials have been used as the pigment base, from corn starch and potatoes to china clay, barytes, or whiting, but the majority of these have little value. Vegetable substances will in time decay, while soft mineral bases, such as china clay or whiting, are unfit for the purpose, as they absorb moisture from the wood and swell. The best pigment base for a wood filler is very finely ground silex or quartz. When dry, this is a white powder; but when mixed with a quick drying oil varnish, it becomes transparent and remains so even after the hardening of the var nish film. One test of a good filler is to spread a little of it upon a clear white board, and rub it back and forth with the blade of a palette knife for a few minutes. The silex, being very hard and having a slight grit—although it should be ground so fine that the grit cannot be detected by the fingers—will wear away the surface of the knife very slightly, yet suffi ciently to darken the board. A filler that is not made of silex will show no darkening.