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Use a stain to colour the wood without hiding the grain. This is a particularly desirable finish to use on floors, furniture, and other woodwork about the house where it is important not to cover the natural wood grain with layers of paint. After the stain has been applied, the general practice is to give the surface of the wood a transparent coat of varnish, shellac, or wax, to protect it. Types of stainStains can be divided into several types. Chemical stains change the colour of the wood by a chemical reaction and are seldom found in the home, as they are very difficult to use. Spirit stains have denatured alcohol as their chief solvent, and this makes them a quick-drying and difficult medium to handle without experience. Water stains are made of colouring that is soluble in water. They were once used extensively, but they require considerable skill if good results are to be obtained. Oil stainThe most popular and widely used stain today is the oil stain. Some kinds of oil stain are used only for protective measures against the weather-such as shingle stains-while others are for decorative effect and are called oil pigment stains. These are the ones with which the home mechanic will most likely deal when staining furniture, floors, and other woodwork about the house. Stains can be purchased ready mixed or they can be mixed at home. If you plan to mix your own, be sure to use only the best materials. Varnish stainsVarnish stains are a combination of varnish and a stain. This kind of finish will usually not be as fine as that produced by the regular process of stain followed by varnish, but it provides an excellent finish for minor pieces of wood. Stain and varnishPreparing the wood and applying oil stain and varnish is fundamentally the same process for all types of woodwork. Stain, it should be remembered, does not offer any protection to the wood surface. The stain permeates the wood, colouring the grain and emphasizing it. On practically every job where stain is used, the surface should be given a coat of varnish, shellac, or wax for protection and added lustre. The surfaceThe first step in staining is to smooth the wood surface. This can be done with sandpaper or steel wool, and the grade , used will depend upon the type of work involved. Start sanding with No. 1 sandpaper and use finer grades as the surface is worked down. Always sand with the grain. If the surface was previously painted or varnished, remove the old finish with a scraper, sandpaper, and steel wool, or with a liquid paint remover.
BleachingIf the wood has been previously stained and the stain is too deep to be removed by sanding, it can be bleached with oxalic acid or with a prepared commercial wood bleach. After bleaching, give the wood another fine sanding, as the bleaching tends to raise the grain of the wood a little. Applying stainAfter the wood has been sanded and all the dust removed, apply the stain with a brush or cloth. Mix the stain thoroughly, then check the colour by putting some of it on a scrap of wood or an inconspicuous portion of the wood that is to be stained. Keep in mind that the stain will dry to a somewhat lighter shade than when first applied. If the stain is too dark, it can be lightened by the addition of a little linseed oil. Take special care with edges that contain end grain. The open pores of this part of the wood will absorb more stain than the other surfaces and, consequently, will dry to a darker colour. One way to avoid this condition is to apply a small amount of stain to the end-grain edges. This will keep their colouring light and uniform with other surfaces. Another method of achieving the same result is to give the end grain a light coat of linseed oil and turpentine, in equal proportions. A light coat of shellac, applied as a filler, will also prevent the absorption of the stain. Stain is generally applied with a brush
and left on the surface for a few minutes in order that it may soak into
the wood. Use a clean cloth to wipe off what remains on the surface. The
longer the stain is left on the wood, the deeper it will penetrate into
the grain of the wood. Wipe evenly so that the surface will be a uniform
shade. It is much better to have the surface too light than too dark.
If the surface is too light, you can apply another coat of stain, but
if it is too dark, the only alternative is to bleach the surface and resand
it.
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