CHAPTER VI
Wood Finishing
69. Filling.—(A.) After wood has been smoothed and made ready to receive the finish, it is prepared byfilling, by which is meant the process of filling the grain so that the finish itself will not soak in. This, if well done, makes it possible to do as good a job of finishing with two or three coats as could be done on some kinds of wood with from five to eight coats without the filling. Open-grained woods, such as oak, ash, etc., especially need filling, as before the process of filling was discovered, the open grain, or cellular part of the wood, had to be filled by shellac, or other expensive material, before there was a surface suitable to receive the polish. (B.) There are two forms of filler—the paste, which is for use upon open-grained woods, andthe liquid, which is adapted to filling the pores of close-grained woods like pine, poplar, cherry, etc., and which takes the place of one coat of the more expensive shellac or other finish. The paste may be purchased ready-made, and colored to suit the taste, or it may be made by using whiting, silex, or corn starch, and any dry colors necessary to secure the desired stain. The ingredients should be well ground, and thoroughly mixed with boiled linseed oil to a thick paste; to this should be added as much japan drier as there is of the oil, or one quarter as much as there is of the paste. The whole maythen be thinned with turpentine, benzine, or gasolene to a consistency which will allow it to be spread easily, but it should still be quite thick.
(C.) Filler need not be spread very smoothly, but the surface of the wood must be covered, and the filling thoroughly worked into the grain. After this has been done, the wood should be allowed to stand a few minutes, until the filler has become dull or powdery, and seems to stick to the wood if rubbed lightly with the finger, when it should be rubbed off with shavings or excelsior, rubbing across the grain wherever possible. Do not use cloth until cleaning up after the filler is all off, as it is more apt to take the filling out of the grain than either excelsior or shavings. The corners should be cleaned out with a sharp stick, after which the work should stand for several hours, or over night, before the finish is applied, as otherwise the moisture in the filler may cause the finish to bubble. Care should be used that the filling does not stand too long before rubbing off, or it will be very difficult to remove it; hence, it is best not to spread any more than can be cleaned off before it gets too hard. Be sure that there is enough filling mixed to do the job before any is applied, as it is difficult to match colors.
(D.) Liquid filling should be spread as smoothly and as evenly as possible, as the laps will be apt to show through the finish which is spread over it.
70. Staining wood(A.) is for the purpose of imparting some other than the natural color to the wood.
(B.) In finishing open-grained woods, a stain often is used which will color the wood before it is filled, though upon general work, it is the custom to color the stain only.This does not make the work all of one color, as the cells of the wood will retain more filling than will the harder part of the grain. By this method the quarter grain may be made more prominent. If an open-grained wood is being treated, it should be filled after being stained. Close-grained woods are ready for the finish as soon as the stain has dried. Stains which will do the work satisfactorily may be made of various chemicals. There are also many satisfactory stains upon the market, which can be purchased in as small packages as desired, offering the student a large range of colors from which to select.
(C.) Stains for close-grained woods may be made by mixing dry colors with turpentine or benzine, and a little boiled oil and japan to bind the color. These stains should be applied the same as the filler, but not allowed to become so hard before cleaning off, or there will be light places rubbed in the finish. The rubbing or cleaning off should be done with a soft cloth, care being used that there are no places left uncleaned, especially in the corners, as the finish will make them muddy.
(D.) A very goodold cherrystain may be made by mixing Venetian red and rose pink until the desired shade is produced.
(E.)Black walnutmay be imitated by mixing burnt umber with turpentine, oil, and japan, and if a reddish tinge is desired, a little burnt sienna may be added; this is a much better color than can be produced by umber alone. Asphaltum, thinned to the desired color, makes a good walnut stain.
(F.) Many of the best stains are mixed with water as a vehicle, as a depth and brilliancy of color may be obtainedwhich is impossible with any stain that has oil in it. The objection to using water is that the grain of the wood is lifted by the moisture, and has to be sanded smooth before it can be finished. Even with this serious objection, water stains are used extensively upon the best work.
(G.) The rich mahogany stain which is so much admired may be made by mixing the same colors as mentioned in (D.), and adding carmine until the desired color is obtained. An oil stain will not give the best results, therefore a water stain should be used, with a piece of gum arabic about twice the size of a pea dissolved in a pint or less of the stain for a binder, or about the same proportion of mucilage. This stain should be cleaned off the same as the oil stain above described.
(H.) Cherry may be darkened by applying nitric acid; other woods may be darkened or aged by using ammonia, potash, or a strong solution of tobacco or coffee. Nitrate of silver, if exposed to the sunlight, gives a beautiful brown.
(I.) A rich brown may be produced by using equal parts of permanganate of potash and sulphate of magnesia, dissolved in water; as many coats as desired may be applied, sanding with number 00 sandpaper between the coats. Better results are obtained if the stain is applied hot.
(J.) A beautiful green of any intensity may be produced by mixing verdigris and indigo in hot vinegar, and applying hot. Several coats may be necessary, sanding between the coats. The indigo should be used cautiously, or the green may have too much of a bluish cast.
(K.) A rich brownish black may be obtained by using a solution of logwood (pulverized) and sulphate of iron, applied in coats in the order named. Each solution should be hot.
(L.)Ebonymay be obtained by giving any close-grained wood, cherry preferred, a coat of sulphate of iron, using a weak solution, and after that has dried and been sanded, a coat of solution of nutgalls. If the iron is too strong, a white efflorescence will appear, which in open-grained woods will bring out the grain in strong relief. If this is objectionable, the grain should be filled with a black filler.
(M.)Shellac(see71, A.) and boneblack, if well mixed, make an ebony finish which is often used upon common work; black varnish sometimes is used the same as black shellac, but for the best work these are not satisfactory, as they do not strike into the wood to the same extent as do acid, turpentine, or water stain.
71. Shellac.—(A.) This is a product of Africa and South America. It is the combination of a secretion of the female of a small insect and the sap of a tree, in the bark of which the insect deposits its eggs. The gum thus formed is gathered, and after passing through various refining processes becomes the shellac known to commerce. It is cut or dissolved by either wood or grain alcohol, when it is ready for use. Some of the best furniture is finished with shellac, and unless continuously exposed to moisture or hard usage, the finish is practically everlasting.
(B.) Shellac finish does not crack as varnish is liable to, neither does its luster dim by exposure to the various gases present in every house, which are due to domestic causes, though most varnishes will do this after some years.
Upon ordinary work, two coats of shellac may be satisfactory, though three coats generally will improve the work sufficiently to make it advisable to apply the extra coat. Shellac should not be laid in too thick coats, or itwill pit badly in drying, and make work in rubbing to a surface, which can be avoided if moderately thin coats are spread, though perhaps the greatest advantage in laying thin coats is that the wood may be covered more evenly, and there will be fewer runs and laps visible. Shellac should always be laid with quick strokes, never working over a place already covered; for this work, use a brush as large as possible to do the work without clumsiness.
(C.) In applying shellac finish, one coat is laid upon the other, each coat being rubbed down with number 00 sandpaper, or with pulverized pumice stone before the next coat is spread. For this purpose, a sheet of sandpaper should be cut into eighths, and one of these pieces folded in the center of its long dimension, and held in the hand as shown in Fig. 99, which keeps its edges from scratching the surface. If it is desired to rub the shellac down to a surface with pumice stone, it should be applied with hair-cloth, or with harness maker’s felt, moistened with oil or water; but for ordinary work, sandpaper will give satisfaction, and as it is more convenient, it is much used.
If the best results are desired, the last coat should be rubbed with pumice stone and sweet oil, applied as above, though boiled oil is satisfactory; and for ordinary work, number 00 sandpaper is used, though it is liable to show scratches. After the rubbing is done, the oil should be wiped off with a soft rag, and very fine rotten stone dusted on and polished with a clean, soft cloth. Many finishers use the palm of the hand in putting on the finishing touches. If a dead, or mat, finish is desired, the final rubbing should be done with water, used sparingly, as oil imparts a high gloss, if the work is well done.
(D.) Care should be used on any kind of work upon which waste or oily rags are used; these rags should be gathered and burned unless they are wanted again soon, in which case they may be spread out separately; since, if crushed together and thrown, as they often are, into a waste box, they furnish the necessary conditions for a case of spontaneous combustion.
Fig. 99.—Method of Grasping Sandpaper in Rubbing Down ShellacFinish.
Fig. 99.—Method of Grasping Sandpaper in Rubbing Down ShellacFinish.
(E.) The gloss upon dried shellac and varnishes of all kinds is very showy, and lacks the finish and the texture of a rubbed finish. Moreover, any dust settling upon moist varnish is held, giving the surface an effect of countless minute points; rubbing removes these, and gives the smooth, glossy surface desired upon most work. Uponthe most artistic furniture, a gloss, which is the result of a built-up polish, is not considered good taste; the use of muscle and a very little oil, applied at intervals during a term of years, gives a polish and a beauty which can be obtained by no other method, and it is to attain this ideal in a few days that so many varieties of finish exist.
(F.) In rubbing, be sure that the corners are not rubbed through, as the pressure will naturally be more upon the corners than upon a broad surface. This may be avoided by using care that the pressure is not applied so as to bear on the corner; grasp the rubbing material in such a way that no loose edges will be beyond control, as in Fig. 99, or the finish may be badly scratched; this applies especially to the corners. The rubbing should always be in the direction parallel with the grain of the wood.
(G.) If the finish is rubbed through to the wood, it may be repolished or patched by sandpapering the bare wood with fine sandpaper, and staining it to bring it to the same condition as the rest of the wood before the first coat of finish was applied. Using the same finishing material as the finish of the rest of the piece, lay a very thin coat, a little larger than the place to be patched, being careful to avoid a ridge at the edge of the patch. This ridge may be drawn out by a small camel’s-hair brush, and the patch left until thoroughly dried; then apply another patch a little larger than the first one, treating the edge as in the first patch. Continue this until the finish is built up to the same thickness as that of which it is a part. This should be rubbed very carefully to bring it to the same finish as the rest of the surface, using care not to rub through the old finish at the edge of the patch. As itis the corners which are most liable to be rubbed through, this process will not generally be difficult of application; all that is necessary to secure a successful patch is to use care at each step, and not to hurry the drying of the different patches.
72. Wax finishingis a good method of finishing any kind of hard or dark-colored wood; (A.) it does not give as satisfactory results, however, as do some other methods of finishing, upon soft or light-colored wood. There are a number of different kinds of wax finishes which can be purchased in almost any desired quantity, (B.) but an economical and satisfactory wax finish may be made by dissolving as much pulverized resin as may be picked up on a cent in a half pint of turpentine or gasolene heated in a water or steam double vessel. After this is clear, cut up and add a piece of beeswax as large as a thimble, and allow the finish to simmer slowly, until it is clear, when it is ready for use. This may be mixed in larger quantities by using the same proportions. If placed in an air-tight vessel, it will keep indefinitely.
(C.) This finish should be applied hot, with a brush, as smoothly and as evenly as possible, and allowed to stand until it has become quite hard, when it should be polished with a soft rag which is free from lint. As many coats as desired may be applied, each coat being treated in the same way, and adding to the beauty of the finish. Another method of applying this finish, and which gives satisfactory results upon broad surfaces, is to make a pad of a rag, and rub the wax on the wood, rubbing until it is dry. This is not as satisfactory as it is to use a brush upon work where there are many corners to finish around.
One of the advantages of this wax finish is that it may be brightened if it becomes dim by going over it with a soft cloth, or it may be renewed and improved by another coat at slight expense and little trouble.
This is also a satisfactory method of finishing a dark floor made of a wood which will not splinter when it is rubbed.
73.(A.)Oil finishis perhaps the most simple way to finish a piece of furniture; it is best adapted to hard, dark woods. The material is made by mixing a quarter of a pint of turpentine with seven eighths of a quart of boiled linseed oil. It should be spread evenly over the surface to be finished, and should stand until as much of it as will, has soaked into the wood, when the surface should be brought to a finish by rubbing. This will require muscle, as the finish should stand about ten hours, during which time a thin film or skin will form, which must be removed by rubbing. Only a soft rag, free from lint, should be used, and be sure that the folds of the cloth do not leave their marks upon the surface. Rub with the grain.
(B.) Oil finish is a very durable finish, easily taken care of, and is used to some extent in finishing the most artistic furniture, being especially adapted to finishing mahogany. It has a character peculiarly its own, and exposure to moisture and heat affects it less than almost any other form of finish. As it should be occasionally oiled, it improves with age and care. This finish was used in olden times, and the care of generations gives a polish attainable by no other method.
74. Varnishforms the finish which is used most commonly upon all grades and kinds of work. (A.) The different grades are made of various vegetable gums andresins, cut in turpentine and mixed with boiled oil. A cheap grade of varnish or hard oil may be made by boiling resin, turpentine, and boiled oil together. Other gums may be treated the same way; the varnish used upon the best work, for instance, is made from copal, a vegetable product of the tropics. By a very careful process of boiling, straining, and ripening, extending over months, copal is made into the product which is used so extensively upon furniture finishing, carriages, etc.
(B.) Varnish should be applied in a room heated to about 80° F., the dust should be laid by sprinkling, and there should be no drafts of air, nor flies or other insects to light upon it, if the best results are desired.
(C.) In flowing varnish, instead of laying a thin coat as in shellac, a thick coat should be applied. This may be done by using a thick, heavy brush; some prefer a heavy, round brush, and others think they can obtain the best results from a broad, flat brush. The finer the hairs, the better the results obtained.
The brush must be taken up full of varnish, enough to cover the entire surface, if possible, and spread or flowed very quickly. The brush should then be wiped out in the varnish pot. With the brush thus dried, go over the surface, picking up all that the brush will absorb; wipe this out in the pot, and repeat the operation until nothing is left but a thin film of varnish. If this is done properly, it will prevent all runs and streaks which result from unskillful workmanship.
When this coat is thoroughly dried, rub with number 00 sandpaper, pulverized pumice stone, or a smooth block of pumice stone (carriage painter’s method), and repeat theprocess until the desired body of varnish is obtained. Rub down last coat with oil and polish. Allow as much time between last coats as possible, as the harder the varnish is, the better and more durable the work will be when completed.
75. Polishing.—This term applies to the process by which a polish is built up by rubbing, or “ragging” as workmen sometimes call it. The piece to be polished should receive two or three coats of shellac or varnish, which should be rubbed down to a surface, when it is ready for the polish.
To make a pad of convenient size for polishing, fold a piece of old, soft cloth, free from lint, and fill it with cotton waste; or the end of a roll of cloth may be covered by the piece which is to do the actual polishing. Provide a cup of moderately thin shellac and another of boiled oil, of which about one quarter is turpentine; or better, a cup of sweet oil without turpentine. Dip the pad into the oil and allow it to soak in completely, then do the same with the shellac. Now dip the pad again into the shellac, and with the finger put on a single drop of oil, and rub lightly upon the work, with a circular motion, or if the work is large enough, the stroke may be longer. If the work is done with a straight stroke, do not stop at the end of the stroke, as the instant between the end of one stroke and the beginning of the return may be enough to allow the shellac to stick and make a hole in the surface, which will be difficult to repair; begin and end the stroke with a sweeping motion. The idea of this method of polishing is to bring the shellac to a polish, using as little oil as possible for lubricating, as the less oil used, the better will be the polish.
76. Brushes.—(A.) If brushes are to be used for stain or for filling, a cheap brush of any suitable size will do, a flat brush being preferred upon ordinary work. For shellac and varnish, the finer the brush, the better the results usually obtained. Ordinarily it is the best practice to use as large a brush as the nature of the work will permit, as it will hold more, and cover more surface, than a smaller brush, and have fewer “laps.” Chisel-pointed, flat brushes, from 1½” to 2½” in width, will be found satisfactory for the work of schools and amateurs, but upon professional work, brushes from 3½” to 5” often are used.
(B.) The care of the brushes is an important part of the work of those who use them, as neglect or carelessness may destroy a valuable brush overnight. Unless a brush is going to be used again the next day, it is always best to clean it thoroughly. If a stain, filling, paint, or varnish brush, use gasolene or turpentine, but if a shellac brush, use wood alcohol, cleaning off all the small particles. To obtain the best results, all brushes should be washed in hot, soapy water, and afterward rinsed in clean water; in general, however, this latter precaution may be dispensed with, unless the brushes are to be laid away indefinitely. Unless the above precautions have been taken, care should be taken that shellac and varnish brushes are not changed from one to the other. Never allow a brush to stand on its side for more than a few minutes at a time, as a wrong direction is easily given the bristles, and the brushes may be quickly destroyed by a little carelessness or negligence.
Old brushes, well broken in and cared for, will give better results than new brushes; therefore they should be treated with every possible consideration.
Varnish brushes often are left in the varnish pot, and if they are hung up so that they will not rest upon their bristles, this is the best way to keep them when they are in almost constant daily use.
Suggestive Exercises69. Why is wood filler used? Describe paste filler. Describe the process of spreading filler and of rubbing it off. Describe liquid filler and the process of spreading it.70. Why do we stain wood? What is the difference in the results of staining and filling and of filling alone? How may stains for open-grained woods be mixed and used? Describe a simple cherry or mahogany stain. Describe black walnut stain. What is the objection to a water stain? How may a rich mahogany stain be mixed? How may woods be darkened? Describe the composition of a rich brown stain; of a good green stain; of a brownish black. Describe ebonizing. For what purposes are shellac and lampblack and black varnish used?71. Of what does shellac finish consist? What is the source of supply of shellac? Compare shellac and copal varnish. Demonstrate the application of shellac. Are thin or thick coats of shellac the better? Why is rubbing down necessary? Demonstrate. What precautions should be taken in regard to oily rags? Why? What should be guarded against in rubbing? What is a convenient size for a piece of sandpaper? Describe and demonstrate patching.72. Describe the preparation of wax finish. Describe and demonstrate two methods of applying wax finish.73. Describe oil finish and its application. Describe its qualities.74. Describe briefly the manufacture of varnish. Describe ideal conditions for flowing varnish. Describe and demonstrate the method of flowing varnish.75. Describe and demonstrate the process of polishing.76. Describe the kinds of brushes suitable for different kinds of work. How should brushes be cleaned? What should be the general treatment of a brush? How may varnish brushes be kept ready for use?
Suggestive Exercises
69. Why is wood filler used? Describe paste filler. Describe the process of spreading filler and of rubbing it off. Describe liquid filler and the process of spreading it.
70. Why do we stain wood? What is the difference in the results of staining and filling and of filling alone? How may stains for open-grained woods be mixed and used? Describe a simple cherry or mahogany stain. Describe black walnut stain. What is the objection to a water stain? How may a rich mahogany stain be mixed? How may woods be darkened? Describe the composition of a rich brown stain; of a good green stain; of a brownish black. Describe ebonizing. For what purposes are shellac and lampblack and black varnish used?
71. Of what does shellac finish consist? What is the source of supply of shellac? Compare shellac and copal varnish. Demonstrate the application of shellac. Are thin or thick coats of shellac the better? Why is rubbing down necessary? Demonstrate. What precautions should be taken in regard to oily rags? Why? What should be guarded against in rubbing? What is a convenient size for a piece of sandpaper? Describe and demonstrate patching.
72. Describe the preparation of wax finish. Describe and demonstrate two methods of applying wax finish.
73. Describe oil finish and its application. Describe its qualities.
74. Describe briefly the manufacture of varnish. Describe ideal conditions for flowing varnish. Describe and demonstrate the method of flowing varnish.
75. Describe and demonstrate the process of polishing.
76. Describe the kinds of brushes suitable for different kinds of work. How should brushes be cleaned? What should be the general treatment of a brush? How may varnish brushes be kept ready for use?