15. Finishing

Principles and method - Sanding, steel wool, filling - Wax finishing methods and material -French polish method and materials – Cellulose process – Staining

Wood finishing normally involves a considerable number of separate processes, all of which are quite an art in themselves, if perfection is aimed at. The two distinct aspects of quality in any wood finishing are appearance, which will be the chief factor if articles are to be saleable, and durability, which will have a great influence on the reputation of the craftsman. The first stage in finishing is sanding, of course, but do not get the idea that sand paper alone will give you a suitable surface for final polishing.

If the work has been turned badly, due to incorrect use of your tools, no amount of sanding will put matters right. I made a point in earlier chapters of asking you to use your gouges and chisels, so that the wood is cut and not chipped away, and if you find that you still have rough spots before sanding, try and remove them by taking a light cut with the gouge on its edge.

Our first stage will be to use a piece of medium grade sand paper, such as M2, folded double and held between fingers and thumb. Assuming that at the moment we are turning between centres, the sand paper is applied to the underside of the work, with palm upwards. If this method is used it is quite easy to let go of the sand paper and avoid having an accident with your fingers if anything should go wrong or you apply too much pressure. If, on the other hand, you apply the sand paper to the work palm downwards and on top of the lathe, there is the possibility, that should you apply too much pressure to the work, your fingers will be trapped between the work and the tool rest, and that can be very unpleasant. These simple explanations will also apply whilst polishing or using steel wool.

The sand paper is now worked alternately from left to right, along the whole of the work to avoid spiral scratches forming on the wood; too much pressure will also cause spirals which are very difficult to remove once they have been made. When you come to beads and coves, the sand paper is carefully shaped between the fingers so as to retain the original patterns. Be very careful where the design changes from concave to convex, and where there are fillets, which must be kept clean cut.

The medium grade sand paper is now changed for a finer grade and the whole process repeated. Remember to apply only light pressure as too heavy a touch will wear the sand paper away and not the wood, which is just a waste of time and money. If a super finish is required or there is evidence of sanding scratches, it is a very good idea to use a wad of medium grade steel wool. One big advantage of this material is that it can be used over and over again.

On the market today, there are all sorts of substitutes for sand paper and glass paper. One, for example which comes to mind, is a wire gauze which is very good, but gets blocked quickly and gets one hot round the collar, so I still prefer the old fashioned stuff. It is quite cheap and I do not mind throwing it away, when I have done with it. Garnet paper is very good and retains its cutting power much longer than sand paper but it is more expensive and is not usually stocked at hardware stores or ironmongers, particularly in country districts.

Bowls and faceplate work are treated in a similar manner to work between centres and the sand paper held between fingers and thumb, is presented to the work so that the action of the rotating wood is to take the sand paper away from you, should too much pressure be applied. The inside of a bowl, for example, is sanded first from the centre out­wards and vice versa, taking care at the very centre of the bowl and the sides, where there is cross grain work to sand.

So much, then, for the groundwork, but do not throw all your old pieces of worn paper away. They will come in very useful for another stage in one of my methods of finishing.

Many turned articles rely on the natural beauty of the wood and require no artificial colouring. Walnut, rosewood, lacewood (plane tree), maple, cherry and many other beautiful timbers are best finished with a clear polish, and perhaps the easiest is the wax finish. I am very much in favour of this finish, as it can be carried out completely on the lathe without removing the wood until the whole process is finished. Furthermore, as most woodturners' sheds are full of dust and chips, if we have to apply a varnish or lacquer which is sticky to handle, we shall spend half of our time picking bits and pieces off our partly finished work.

Wax finish. Take a piece of pure beeswax and with the lathe turning at moderate speed, say 2,000 r.p.m., approxi­mately, press the wax into the wood. You will see that we have a mixture of wood dust and wax forced into the grain of the wood and if it is at all open grained, the work will be most satisfactorily filled and, what is more important, the filler thus made will match the wood perfectly and sealed the grain in one operation. Stop the lathe for a moment and inspect your work, if it appears to be streaked with wax, start the lathe up again and use some steel wool, that piece you used in the sanding operation will do, and apply it lightly to the whole of the work. The next stage is to seal in the wax and wood dust, and for this operation we require some clear or white french polish, commercial grade, if you can get hold of some. Garnet or button polish can be used but, unless great care is exercised it will form dirty brown streaks on the work. Make a small pad of some material that will not fluff, in very much the same way as for normal french polishing, and charge it with french polish. Apply this pad to the revolving work, a small area at a time, recharging the pad when it becomes dry. Continue until the whole area is covered and carry on using the pad until a slight polish is obtained. Stop the work and inspect it and if there is any sign of rough spots due to grain raising, use a little steel wool—not sand paper—to remove these. Apply the second coat of polish and endeavour to work up a reasonable shine but do not be put off if at this stage, your work does not appear to be over brilüant, as the next stage will put matters right. Finally take a block of carnauba wax and apply this to the revolving work to form a thin film over the whole surface of the work. Then, with a bunch of shavings in the palm of your hand, work over the whole turning, so that the heat caused by friction will spread the carnauba wax evenly over the whole work.

It will be apparent that your work has taken a new appearance almost immediately and has a very pleasant shine. To finish off, a light rub over with a piece of artificial silk will complete the process. There is only one small difficulty which may arise in using the carnauba wax. This substance, which originates from Japan, is very hard and brittle and if too much is applied to the work, the whole effect is spoiled. On the other hand, if too much pressure is used when polishing with a rag, the whole application of carnauba wax will be rubbed off, so you see, a little practice is required in this last operation.

This combined wax, french polish, carnauba finish is very durable and attractive in appearance. If it is scratched it can easily be removed with a sharp rub with a piece of cloth. Furthermore, it is non-sticky.

Beeswax can be used on its own and polished with shavings and a cloth but it does not retain its brilliance and is sticky to touch. On the other hand, carnauba can also be used on its own for a very quick finish but it is not very durable owing to its brittle nature, and if too much is applied, the appearance is apt to be rather white and unnatural.

On the market today, there are numerous prepared wax polishes which are quite suitable for wood finishing, although ordinary shoe polishes take a lot of beating and can be obtained in several shades. A very good polish can be prepared at home using equal parts of beeswax, carnauba wax and turpentine. The carnauba is first powdered and added to the turpentine, the beeswax is shredded and heated until it just melts, and is added to the carnauba and turpen­tine, allowing the whole mixture to set into a fairly stiff paste. If the wood is previously sealed with french polish, a more lasting brilliance will be obtained.

Filling and sealing. When turnings are made in open grained wood such as oak, chestnut, elm or mahogany, it is always necessary to fill the grain to speed up polishing. French polishing can be used as a filling and sealing opera­tion on its own, but for a quicker finish a separate filler will help a lot, particularly on end grain.

In my previous description of wax finishing, you will have noticed that I used beeswax sanded in as a filler, and this I find to be most satisfactory, even though the work may be french polished. A good paste filler can be made using putty thinned to a paste with turpentine, or any of the packeted fillers used in home decorating will suffice. If a colour is required, add a few drops of stain to obtain the desired shade. Paste fillers should be applied with a rag or brush after the work has been stained to the requisite colour, and left to dry until the appearance of the work takes on a dull look. The work is then turned at slow speed and the filler worked into the wood with a coarse piece of cloth. Allow time to dry and then brush on a sealer coat of french polish.

Sealing the grain is very important particularly after filling and staining, otherwise the wood will just keep on soaking up polish in the open, grain portions. Sealing will also prevent the centrifugal force of the lathe throwing out the filler and stain, and on large diameter turnings such as bases for standard lamps, this quite often happens if the wrong type of stain is used.

Staining. I always prefer to finish woods in their natural colours, but often one wishes to stain some of the less inter­esting timbers. Various stains are obtainable and each has its uses and some have a few disadvantages, and it must be left to the individual to choose the one which suits his needs. Water stains are made up of soluble crystals which are added to water to the desired shade and are obtainable from most handicraft shops. These have the disadvantage of raising the grain, but they are cheap and will stain most woods satisfactory. Woods of an oily nature do not take water stains well. There is one important feature which must be borne in mind when staining and that is the effect of subse­quent applications of polish. Some stains will be removed or the colour changed by the subsequent sealing and polishing and this must be avoided. Water stains, however, behave very well in this respect.

We also have the spirit stains. These are crystals which are soluble in methylated spirits, but again, these have the disadvantage of raising the grain, but their rapid drying qualities give them an advantage over others. Application of french polish on top of a spirit stain will remove some of it and may make turned work appear streaky.

The best stains for amateur use, are, no doubt, the oil or naphtha based stains and are obtainable ready mixed in various shades. Here there is no grain raising and they will take to most wood, although American and English oak can, at times, prove rather difficult. The stain can be applied with a rag or brush and after a few minutes surplus stain is wiped off. The time taken to dry is usually two to three hours. French polish will seal in the stain before subse­quent polishing. If french polish or shellac is applied to oil based stain before it is dry, centrifugal force of the lathe, whilst polishing, will throw out some of the stain and it will be difficult to obtain a good finish.

Cellulose stains and finishing materials are available. They are chiefly used in factories and the furniture trade, but are quite suitable for turnings if a quick finish is required, although there is quite an art in using them by hand, as they are really intended for spray application. Cellulose stains are quick drying and there is little grain raising, but care must be exercised in the choice of materials for finishing. French polish or shellac is again the best for a sealing coat. Cellulose sealers will tend to remove the stain as it is a solvent for other cellulose products. With all finishing methods we must be on the look out for subsequent coats of polish or sealer removing the previous coat. The following will help you in your choice of stains and sealers.

water stains. Raise grain. Seal with shellac, french polish or cellulose. spirit stains. Raise grain. Seal with cellulose sealer or very quick application of french polish or shellac. oil or naphtha stain. Seal with french polish or shellac. cellulose stain. Seal with french polish or shellac.

One thing to remember about cellulose finishes is that they will not dry if applied over wax. If you have used beeswax sanded in as a filler, seal it in with french polish before applying any cellulose.

Finally, there is that old antique finish in oak which can be obtained either by fuming with strong ammonia or by immersing the turning in a can of strong soda water, which will give it a lovely mellow tint. To fume oak turnings, all that is required is a good air-tight box, such as a tea chest, fitted with a lid. Place a small amount of extra strong ammonia in a saucer in the bottom of the box, put in the turnings arranged so that they are not touching each other. Put on the lid and cover with an old, wet blanket and leave for 24 hours or so. The resulting stained oak will require a straight wax finish to give it that lovely antique appearance, and do not forget to knock it about a bit and, bore a few small wormholes, just to complete the illusion!

French polishing. A french polish, is perhaps, one of the best types of finish suited for lathe work, as the frictional heat generated ensures quick drying and the work can be handled soon after the polish has been applied. In the french polishing of furniture, a great deal of work goes into the preparation of the rubber but for lathe work, we do not require anything quite as elaborate. Two shallow containers, such as tin lids, are needed, one filled with french polish and the other with a little linseed oil. Place these containers by your side, arranged so that you do not have to reach over the lathe to get at them. A piece of lintless cloth or cheese­cloth is rolled up into a pad which can be conveniently held between the fingers. The lathe is now set to operate at about 1,000 r.p.m., but this speed depends on the diameter of the work, to a great extent. For a 10 in. diameter bowl, a slightly slower speed will be required. I am assuming that the wood has been stained and filled and that all the groundwork has been done and it is ready to be polished.

Dip the pad into the french polish and apply a little linseed oil to the pad with one finger; do not over-oil the pad. The object of using linseed oil is to prevent the pad from sticking and also to help spread the polish over the work. With the work turning under power, the prepared pad is brought into contact with the work. The pad is moved progressively along the work, considerable pressure being brought to bear by the fingers and thumb. The pad should be recharged when it becomes dry, and again a spot of oil is applied. Whilst the pad is in use, it should also be squeezed between the fingers, so that the polish in the pad is forced out and on to the revolving wood. You will notice that a shine soon develops on the work and polishing should continue until the whole work is covered with a good layer of polish. After polishing do not throw your pad away but put a few drops of polish on it and store in a screw-top jar. You will find that when you use it again, you will get a polish much easier and quicker.

Finally, a good buffing with a clean, dry rag will remove any trace of the linseed oil. French polish will take quite well on top of a wax polish, if the surface is first rubbed with steel wool.

If you have several turnings to polish and require a quick finish with the minimum amount of polishing, first of all brush on a good layer of spirit varnish. Spirit varnish in the trade, is called white hard varnish for the clear variety, and brown hard for the darker, and has the con­sistency of thin syrup. After it has dried hard, which will be in about two hours, remount the work in the lathe, and, turning at about 1,000 r.p.m., flatten the work with steel wool, not glass paper. A quick wipe over with your french polishing pad, will give you a very good polish, although the surface will not be quite so hard as a fully french polished work.

Clear oil varnish can be used for finishing but is not to be recommended.

Cellulose finishing. One hears very little about cellulose being used for lathe work, but when the method has been mastered, a very good hard finish can result. The work should be fully prepared for polishing and sealed with shellac or french polish. This is very important. Cellulose is a very strong solvent for most stains and varnishes but will not affect shellac and spirit based polishes. With the work in the lathe, and turning by hand, quickly brush on two or three coats of clear cellulose lacquer. In between each coat, flatten the surface with steel wool, the work rotating at its slowest speed under power. Stop the lathe and inspect the work for ridges in the polish and remove with steel wool, if there are any. Prepare a small pad out of a piece of chamois leather and apply sufficient cellulose thinners to just moisten the pad. Cellulose pullover solution is better, if you have a friend in a car spraying shop. With the lathe turning at slow speed, apply the chamois pad to the revolving work and make one very quick, light pass along the whole length of the work. Wait a few minutes and make a second pass in the same direction. On no account must you let the pad stop in any one position, or you will dissolve the previous application of lacquer, then you will have to start all over again.

Bowls can be treated in the same way but, again, make only one quick stroke in one direction. Do not move the pad backwards and forwards as in french polishing. For satisfactory french polishing and cellulose finish, it is most important to have a warm, dry atmosphere in your work­shop ; a temperature of not less than 6O°F should be aimed at. A good indication of the temperature and humidity is to note the appearance of your polished work. If it is too cold and damp a whitish bloom will form. If this occurs, the articles must be repolished when conditions are a little warmer, and the blooming will disappear.

Oil finish. Turned articles such as bowls and plates used for holding food should be finished with salad oil, or a vegetable cooking fat, the wood being thus protected from moisture or odours being retained in the wood. The work should be well sanded to a smooth finish and the oil or cooking fat applied with a clean cloth, with the lathe turning at about 600 r.p.m. A number of applications will be required to build up a long lasting finish. Articles so finished must not be washed but after use a wipe over with salad oil is all that needs to be done. In time the articles will develop a beautiful, mellow appearance.

Novelty finish. Small turned articles, such as one sees in gift shops at the seaside, can be given a colourful and unusual appearance with ordinary stationers' sealing wax. This is applied by supporting the sealing wax on the tool rest and pressing the end against the revolving work, which should be rotating at about 2,000 r.p.m. Heat caused by friction, will cause the wax to melt, forming ridges of wax in a corded effect. Since sealing wax can be obtained in many colours, it is possible to get a very decorative effect.

All turned work will finish better if a number of days can be left between actual turning and finishing. This allows for any fibres of wood that were flattened by turning, to spring up, thus making subsequent sanding much more effective, but most of you will prefer to turn and finish at the same time.

Spray finish. Most turned articles, as already explained, can be finished completely whilst still on the lathe. However, small articles, consisting of partly turned parts, such as wall brackets and fancy goods, can be finished by the application of a spray polish. Most amateurs have access to a vacuum cleaner operated spray gun and this can be used with quite satisfactory results. After the various parts have been assembled and sanded, and stained where required, the articles should be placed on a narrow board at a con­venient height. The spray gun is filled with a mixture of 2 parts cellulose thinners and 1 part sanding sealer. This is a specially prepared product for sealing the grain, which reduces grain raising to a minimum. Use the spray gun with a sweeping action, being careful not to stop in any one position. The solution being of a very thin nature, will require two or three coats at least to give a satisfactory build up.

Allow ten minutes or so between each coat and finally about two hours to dry off. All parts should then be sanded with a very fine grade of sand paper. Then comes the applica­tion of the final coats of lacquer. Again mix up a solution consisting of 2 parts cellulose thinners to 1 part clear cellulose lacquer, and apply several coats in a similar manner to the sealer coat. As with other forms of polishing, temperature takes a leading part in obtaining a satisfactory finish. Never attempt spraying if the atmosphere is cold or damp, or both. 6O°F is a satisfactory temperature. To obtain a real high gloss finish, a light rub over with a pad of chamois leather, moistened with cellulose pullover solution, or if this is not obtainable, cellulose thinners, will do the trick. Whatever you use for this operation, keep the pad on the move. If you stop in one place, it will stick and pull off the previous application of lacquer.

Some very attractive finishes can be obtained using spray stains, particularly where various woods have been used together to form one finished object, as in the case of a floor lamp standard.

If you are lucky enough to possess a high pressure spray plant, then the ratio of lacquer to thinners can be increased to equal proportions of each solution.

Finally, there is the dipping method. This is mostly used in the finishing of tool handles and very small parts and is not really suitable for amateur use but the process is quite simple, and perhaps you would like to experiment. The parts to be treated are suspended from a beam of wood and immersed into a bath of a fairly thick cellulose lacquer. The beam with the suspended parts is slowly withdrawn from the lacquer by mechanical means, the parts drying off as they are removed. The amateur may not consider this process a practical proposition, but if you are going to produce a great number of tool handles or similar items, it is worth considering the possibilities.

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