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Polishing and Staining

Explaining the Various Finishing Processes Suitable for Different Kinds of Wood
By Ray Lewhite.

There are several methods of polishing woodwork, and it is always a matter of opinion as to which method is preferable. Most work is finished with a highly polished surface, but certain classes of work should be left dull. Again there is the work which is merely oiled, whilst another worker will prefer to add a coat of varnish and leave it at that. Oak looks very nice fumed, which is another method of finishing the work. Plain woodwork can be painted, enamelled, or of course, the wood can be left in its natural state, without treatment of any kind. Or table tops can be covered with Formica. Thus, the worker has seven different methods of completing his work.

Varnishing

Polishing and Staining
Varnishing is certainly the easiest method, and this process merely adds a thick transparent coat to the wood, which allows the grain to be seen, but does not add to its appearance. There are numerous kinds of varnish - water varnish for the protection of paper; elastic varnish, which has to stand expansion and contraction of weather, church varnish, and so on. Do not use varnish on new wood, but first treat the surface with glue size. This will will give a body for the varnish, which would otherwise would be bright in some places and dull where the finish has sunk in. Varnish is very glutinous, and needs special bristles fixed to withstand the pull of the work. Paint brushes are kept in water when not in use, but varnish brushes should be hung in linseed oil or the varnish itself. The best time to do varnishing is in the early morning. If the work is done in a dry atmosphere, a peculiar milky appearance will show, due to moisture getting on the varnish when it is nearly dry. Varnish must not be put on too thickly, but an even amount must be spread over the whole surface. Several coats may be applied if necessary, but a streaky surface must be avoided. The brushes used are flat as seen in Fig.1, but small one can be used for edges or moulding. See that it does not drag, and apply evenly in one direction.

Polishing with Linseed Oil

Polishing and Staining
Oil polishing is quiet a simple process, and is merely a matter of rubbing the wood with raw linseed oil to bring up the grain or "figure" and at the same time to give the work a nice colour. The work, however is a lengthy process to get the best results, for any number of coats can be given with a long space of time between each. Mahogany, beech, or oak are all greatly improved by the application of oil. Everything, however, depends on the continued rubbing until the oil has soaked right in. A polish will not be obtained for some time, and the rubbing must be frequently repeated with as much pressure as possible.

How Oil Polishing is Done

Polishing and Staining
The oil is applied by means of a rubber as shown in Fig.2, where a piece of flannel is wrapped round a pad of wool. It is most suitable for large, flat surfaces. It cannot always be applied to fretwork, as the oil rubs over the edges without actually staining the interior parts. For the same reason, oiling cannot be done on moulding or carved ornaments. The longer the rubbing is continued the better the resulting polish will be. Certain woods naturally take more oil than others, but in every case constant rubbing is essential. It should not be applied too freely, but just sufficient to rub into the wood until it becomes gradually stained and coloured. Raw linseed oil is quiet cheap, and a little goes a long way.

Staining

Polishing and Staining
Very few boards of timber are ever exactly the same shade, even when all of the same class. Trees differ in age and texture, so the boards from them vary in grain and colouring. In consequence, unless the timber is picked with special care (which is not often possible) something must be done to bring all parts of the work to the same shade. Stains must be used to secure this result, and the amateur is now fortunate in being able to obtain these ready to use. The professional uses a number of chemicals to obtain the result - dragons blood, bichromate of potash, tumeric, saffron, cochineal and so on. The amateur need not worry over these, because he buys his material mixed, ready to apply. The stain as its name implies, is a coloured liquid which soaks into the wood and dyes it the colour required, and serves to bring out the grain. There are stains for almost all kinds of wood - oak, mahogany, walnut, and so on, and a wide range of colour is obtainable by there use. One coat of stain will colour the surface - further coats will darken it down to the shade desired. The two principal classes of staining, so far as the amateur is concerned, are the water stain and the spirit stain, which implies the liquid in which the stain is mixed. Both kinds are used in the same way, but each has its advantages and disadvantages. Both kinds are obtainable in all the shades used by the amateur.

Home-made Stain

Polishing and Staining
Water stains are not as powerful as spirit stains, nor are they so quick in action. A spirit stain will soak in and often dry very quickly, whereas the water takes some time. It must not be dried by putting in front of the fire or anything of that sort. One disadvantage of a water stain is its tendency to "raise the grain". The application makes the wood swell, and the surface becomes rough. In consequence, it must be rubbed down with glass paper between each coating of stain. Use a fine paper and be careful not to rub off the actual colouring. One way of overcoming this is to damp the wood first without any stain and then rub it down with glass paper before commencing work. Water stain is naturally cheaper than spirit stain, and is usually sold in the form of crystals. These are mixed with water in a saucer, putting in just the quantity to make the desired shade. Be sure to mix sufficient to complete the job, as it is difficult to make a second quantity exactly the same. Make sure the crystals are dissolved, and try out the colour on some waste piece of wood first. A tin of stain (or dye crystals) will do a large number of jobs if used economically.

Points to Remember

Polishing and Staining
Stains are applied with a flat brush, similar to that used in varnishing, or a gilders mop (see Fig.1), or can be put on with a sponge or a wad of rag. Applying in the direction of the grain quickly and evenly, but do not splash it on in too big a quantity. As mentioned, spirit stain dries very quickly, and in consequence the work must be done quickly. Do not overlap the work with a second coat or a darker patch will result. The end grain always soaks up more than the surface, and additional coats must be given. Take care it does not run. One of the big advantages of stain is that it can be used to alter the wood to imitate other kinds. The grain itself, of course cannot be altered; beech can never be made into oak, for instance. But whitewood can be stained to look like walnut, or pine can be coloured to look like satin-wood, which is yellow. The general use of stains for the amateur, however is confined to darkening the actual woods in there natural shades.

Wax Polishing

Polishing and Staining
A special polishing process, as its name implies, in which beeswax and turpentine, or some similar preparations, are used. Wax polishing creates a surface of soft milky appearance, but has not the high gloss of French polish. It is to be seen in "period" or antique furniture generally, and is most commonly used as a finish for mahogany, oak, or satin walnut. The great advantage of wax polish is that it is simple in application and gives pleasing results. It is most easily used on large plain surfaces, and cannot be recommended for intricately fretted work. Professional polishes, of course, mix their wax, but the amateur is saved the time and trouble by using Waxine. This is ready to use, and a tin contains sufficient for several large jobs if used economically. It is yellowish in colour and is the consistency of butter. Occasionally it becomes hard, and needs melting down. This can be done by holding it on a tin over a flame. Be careful, however, not to let the flame get to the wax because as it contains turpentine, it will easily ignite and blaze up.

The Foundation

Polishing and Staining
The work to be treated should first be cleaned thoroughly and then given a coat of lightning polish to form a bed for the wax. The polish must be allowed to harden in before the waxing is done - otherwise satisfactory results cannot be obtained. Do not overdo the coating of polish, however, for the grain should not be entirely filled up if the best appearance is to be obtained. Care must be taken too, see that neither the wood nor the rubber is damp. The wax is rubbed into the wood with a piece of clean rag, and applied evenly over the whole surface. See that a level surface and coating is maintained - the actual direction of the rubbing does not matter greatly. The great thing in wax polishing is great pressure, for only by hard rubbing is a good surface obtained.

The Work of Wax Polish

Polishing and Staining
When the wax has been rubbed well in, leave the work for a few hours to allow the turpentine to evaporate. Then take another clean soft rag for polishing and go over the whole surface again. Naturally, the more it is rubbed the better will be the result, and it is often helpful to use a block of wood as a rubber, wrapped round with several layers of rag (Fig.3). Again much energetic rubbing is necessary to obtain a good result, but one advantage is that the work can be given further treatment periodically in a similar manner to furniture cream being used on furniture. Oak and similar open-grained wood needs more work than say walnut, but the waxing of oak gives a pleasing and very popular result. Fumed oak is generally treated in this way. The work should be polished, where possible, before being put together, and if there are any ornamental or fretted parts the wax can be rubbed in by means of a close, fairly stiff, small boot-brush or nail-brush.

Fumed Finish

Polishing and Staining
Mention has been made of fuming, and this is another process which those who are fond of oak may like to know something about. Fumed oak is particularly dark shade of wood produced by treating the work to the penetrating fumes of ammonia. This chemical is a liquid obtainable from any chemist for a few pence. It is very strong - usually with a gravity of .880 - so one must be careful of the choking effect of its vapours.

An Airtight Fuming Box

Polishing and Staining
When the oak is placed in an airtight chamber with the ammonia, the fumes of the latter penetrate the wood and the resultant action brings the colour down to a dark brown. The process is quiet simple - the most important feature being to obtain a chest or packing case large enough to contain the work,and so constructed that it can be made airtight without a lot of trouble (Fig.4). To make the packing case airtight, it can be lined with paper and, when the lid has been put on, the cracks are covered with strips glued along. The ammonia is placed in saucers on the floor of the case - two being sufficient for the ordinary amateur work. The more ammonia, naturally, the greater depth of colour, and it is wise to fit a little glass window in the case to know when the work is sufficiently fumed. Another method is to have a slot cut out and through it push a strip of the same wood, as a sort of colour stick. This can be withdrawn periodically for examination. The time required varies with the depth of colour required, and the strength of the ammonia. Light colouring will take place in about 5 hours, whilst a day and a half may be required for a dark shade. The work should be fumed before the parts are assembled and must be laid in the box without any overlapping. Otherwise the parts which are covered will be unaffected by the ammonia. All the work, too, must be thoroughly cleaned with glass paper, care being taken to get off all greasy fingermarks. Uneven results may come from the use of different varieties of oak. Dark patches however, may be made lighter by applying oxalic acid dissolved in warm methylated spirit and put on warm with an old brush. Another treatment for wood on certain occasions is to make its surface dull black. This is a method which can be applied to the background for overlays in cabinets or to panels of small doors to make a striking contrast. The most common use, however, is on the edges of cabinet fronts and edges of speaker cut-outs where the colour serves as a relief and gives the wood a thinner appearance. Eggshell black, so called because the surface it gives has a dull level appearance like an egg. The liquid is applied by means of an ordinary soft paint brush, a smaller one being used to get to the interior frets, or along the thin edges of the work (see Fig.5).

A Polished Black Finish

Polishing and Staining
There is a good amount of spirit in the black so it dries fairly quickly and if a glossy surface is desired, white polish can be mixed with it before use. Hold the work carefully and see that the fingers do not come in contact with any part of the surface which has been coloured until it is thoroughly dry. .
Fig.1.
Fig.2.
Fig.3.
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