Applying Varnish by Rubbing
Applying varnish by rubbing on with sandpaper, pumice stone, and electric means.
¶ The preference for highly polished surfaces of a few years ago has given place to a popular liking for dull lustre and flat finishes on walls, wood trim and furniture. The dull effects take away the new appearance of furniture and trim, making them take their place more modestly in the general decorative scheme.
¶ Some woods, like mahogany and walnut present a far richer effect as wall panels, when finished with a dull lustre and the hand-rubbed surface is much to be preferred on such woods. On these woods and upon oak dull finish is historically correct. A high gloss causes reflections which prevent one from seeing the full beauty of the wood. Next to the hand-rubbed finish the flat varnish finish is preferred. Some believe that was finish is decidedly out of place on walnut and mahogany, but is very appropriate on oak.
¶ The surfaces commonly rubbed dull are gloss varnish, gloss enamel and shellac for the cheaper work. The means of producing a dull finish are several,hand rubbing with pumice stone and oil or water, coating a surface with varnish or enamel which dry with a dull lustre instead of a gloss, waxing a gloss surface, rubbing a gloss surface with sandpaper and oil, or waterproof sandpaper and water, rubbing a gloss surface with steel wool or with an electric rubbing machine which uses pumice stone and oil or water.
¶ Nearly any kind of varnish, shellac or enamel can be rubbed to a dull finish if it is hard dry, but more work is called for on all except the varnishes which are made especially for rubbing. The rubbing varnishes are short-oil and medium-oil varnishes which dry hard and more rapidly than others. If you rub a long-oil varnish or enamel too soon it will gum up the paper badly and rupture the coating to the point of disfiguring it. Of course, if you rub any coating before it is dry the same thing will happen.
¶ Pumice Stone and Water Rubbing. The finest kind of rubbed and polished surface is produced by this method of rubbing the under coats and with the final rub on the finishing coat done with pumice stone and oil.
¶ The pumice stone used for this rubbing is a fine grain, hard abrasive which comes in many grades. The grades are designated as F for a fine grade and FF for a very fine grade. Others grade pumice stone and list it as follows:
¶ Extra Extra Fine, powdered; Extra Fine, powdered; Fine, powdered; No. 0 Usual, powdered; No. 1 Coarse, powdered; No. ½ Grain, powdered; Lump, Select; Lump, Carriage.
¶ The FF grade of pumice is commonly used for rubbing varnish. The tools used for rubbing with pumice stone are simply a piece of felt pad which is fairly soft for fine rubbing and hard for coarse rubbing. The felt is purchased in sheets from ¼ to 1 inch thick by the pound and can be cut to suit the job. Some use pieces cut from old felt hats, but it is too thin for good work. The felt is cut about 3 by 5 inches and tacked at two ends on a block 3 by 4 inches. The felt is turned tip at the two ends and tacked on the ends so the heads of the tacks will not come in contact with the surface being rubbed. There are various kinds: of patented rubbing pads on the market which are excellent for the work. Picture 16 shows one of these. Other things are used for rubbing, such as burlap, curled hair, excelsior, haircloth, etc., but all have their faults and none are as good as felt for the purpose.
¶ The procedure to follow in rubbing with pumice and water is as follows: Slake sure that the varnish or enamel is bone dry and hard before any rubbing is done. Then place the dry pumice stone in a cigar box or any dish which is handy. Soak the felt pad in water and soak the surface to be rubbed in water.
¶ Whenever possible place the surface to be rubbed flat on a bench or on saw horses at a height from the floor which will enable you to rub without leaning over too much. Take the wet felt and dip it into the pumice stone so as to put a thin coating of the dry powder on the pad and begin rubbing the surface with a light pressure first, gradually increasing it to the degree of pressure which you can maintain comfortably for a long time over the whole surface. Bub only with and never across the wood grain, that is, rub in the direction in which the wood fibres extend. If you rub across grain you will scratch the surface so that it will be difficult to remove the marks. Rub in fairly long, straight strokes, never in a circular manner.
¶ Success in rubbing depends upon doing the work methodically., that is, you must cover every inch of the surface with the same pressure and with about the same number of strokes. No need to count the strokes, but a little practice will teach you to quit rubbing when the gloss has been cut off and the grit or dirt nibs disappear. There is no advantage in rubbing beyond that point. No need to cut off any more of the varnish body than you have to to get a dull, smooth surface.
¶ When it comes to rubbing panels where it is not possible to rub the ends without rubbing across grain, rub them first and across grain but do not rub any more than you have to to take off the gloss. Then when rubbing the balance of the panel with the grain you will have to rub out the scratches put in the ends by cross rubbing.
¶ Rubbing is strenuous labor at best, but many finishers work much harder at it than is necessary. If they would use their heads more and their muscles less a better job would result with less work.
¶ The finisher must be especially alert to avoid cutting through the finish at the corners of mouldings, carvings and edges of all overhanging boards. It takes but a stroke or two to cut through at these places so keep away from them with the pad while rubbing the surface generally and go back to them later with a smaller felt and rub them with unusual care. If you do cut through at such places, they should be touched up with shellac colored to match after the surface has been completely rubbed and before the next coat of varnish or enamel is put on.
¶ Another point which must be carefully guarded against is that of rubbing too long in one place. That will heat the varnish enough by friction to burn and ruin it. Burning may also result from rubbing without-sufficient water. The rubbing should be started in one place and should proceed progressively, always in a forward motion. In other words, rnb back and forth a few strokes in one place and then move on to the position next to it and so on.
¶ Add more water to the surface from time to time to keep it wet but it is a good plan not to add more pumice stone to a board or panel being rubbed. Take enough pumice onto the panel when you start rubbing to finish rubbing that panel. The point is that after you have rubbed a little with the pumice it becomes finer as the surface becomes smoother. If you add more pumice stone it will cut faster than the partly worn stone on your pad and it will scratch the fine surface already produced.
¶ Two-coat work will not stand close rubbing, if rubbed at all it should be rubbed lightly. From six to eight strokes in each place will usually be enough to remove the gloss and dirt nibs. For really fine work from four to six coats of varnish are needed.
¶ The rubbing is a very important part of the work of finishing. It makes or breaks the job since expert rubbing adds lustre or depth to the finish.
¶ Keep a sharp lookout for a caking or gumming up of the felt pad. If the varnish or enamel cut off gums or cakes the pad the surface is likely to be scratched. To avoid that wash the pad off in clean water occasionally. If it becomes necessary to add more pumice to a panel or board to finish it use a finer grade than that with which you started so you will not scratch the surface already produced and so make the polishing difficult. Varnish which is not dry will cake up easily and some varnishes will cause caking no matter how dry.
¶ When a varnish or enamel is so dirty or rough that conisderable coarse rubbing is necessary that cuts off what is equivalent to one or one and a half coats of varnish. So it is evident that very little rubbing can be done on anything less than a four-coat job and it also makes clear the desirability of doing clean varnishing work to save rubbing time and labor cost.
¶ The first rubbing done on a job is called coarse rubbing and is done with pumice stone which is not so fine as that used for fine rubbing and it is done with a felt which is only medium hard and from ¼ to 2 inches thick.
¶ Carvings are rubbed with a brush rather than a felt pad which will not of course reach into the depressions.
¶ Pumice Stone and Oil Rubbing. This is called fine rubbing because the object of it, on fine furniture and cabinet work at least, is to remove the fine scratches produced by coarse rubbing. The fine rubbing is often done first with very finest of pumice stone and oil and then after a wash-tip the surface is finished with rot-tenstone which is very fine, sifted and bolted, and oil.
¶ Oil rubbing should never be done on under coats only on the last coat of any finish. If done on under coats the next coat of varnish or enamel may crawl or behave even worse.
¶ Fine rubbing is done with a fine-grained, thin hard felt, and it may be done with either water or oil. As a rule the flow coat, or finishing and polishing coat, of varnish is clean and smooth, the very nature of the varnish makes it so if the application is made under anything like favorable conditions. The rubbing should under no circumstances cut through this coat or the finish will be ruined. This rubbing should not take place until the varnish is hard dry beyond any doubt,at least not until forty-eight hours after application and longer, time for drying is much better.
¶ The oil used for fine rubbing may be any one of several. Raw linseed oil was used in years that have passed. So also was sweet oil in favor. Of late years the non-drying mineral oils have been favored,such as light motor oil thinned a little with benzine, or sewing machine oil. Then there are special rubbing oils put out by all of the large oil refineries which are very good for this purpose. Paraffine oil is liked by some for the work.
¶ When rubbing with oil do not flood the surface, simply dip the pad into the oil and then pick up a thin coating of pumice stone on it. Repeat as often as is necessary to transfer to the panel or board enough pumice to finish rubbing that area. Some finishers prefer to mix the oil with the pumice stone. The rubbing method with oil is identical wjth that used for water rubbing. There is not, however, as much danger of cutting through or burning the surface and for that reason oil rubbing is a little safer for the new hand at it.
¶ After rubbing with oil wipe the surface as clean as possible with cloths and then wash absolutely clean with benzine.
¶ Allow a fine rubbed surface to dry at least twenty-four hours before polishing. Otherwise the polish may not be durable. A longer time for drying and to allow the surface to "sweat" is much better.
¶ Brush Rubbing. For quick and cheaper results in the way of rubbing gloss varnish or shellac a brush is used. For large flat or vertical plain surfaces a short bristled brush like a shoe brush is used, while for general trim and mouldings an old short stub flat wall brush or oval varnish brush is used. The pumice stone is mixed with the oil into a "soup", as the finishers call it. The brush is dipped into the soup and the surface rubbed rapidly. Such rubbing, of course, does no more than to remove the gloss from the surface, but it does very well for some jobs. Note these tools in Picture 17.
¶ Sandpaper and Oil Rubbing. On some of the cheaper work fine sandpaper of the ordinary grades is used after dipping it in one of the oils listed in the pages preceding for pumice stone and oil rubbing. This is a practice which should be extended until it entirely supersedes the practice of sandpapering paint, enamel, etc., dry, a dangerous habit. Breathing the dust from dry sandpapering is perhaps the only real health hazard of the trade today. The paper cuts just as well or better when used with oil. When it clogs up it can be washed with benzine and used again. It leaves no grit on the surface to be cleaned up. The greatest objection to it is that on new woods which are to be finished in as light a natural color as possible, or in gray stains, the oil is apt to darken the wood color. For dark stains, however, the oil has a beneficial effect, since what is absorbed by the wood will seal up the excessively porous places and make the stain take with a more uniform color.
¶ Waterproof Sand and Grit Papers. In recent years these specially made papers covered with sand, glass, emery and other grits of a very fine and uniform nature have made great progress in the favor of furniture, automobile and house finishers. They are used for a great many jobs where pumice stone and water or oil were used in the past. They do just as fine finishing and do it much faster. The cost is much greater for material, but considering the time and labor cost saved they are really cheaper in the end.
¶ To use these papers soak a sheet in water, wet the surface and rub as usual. t It is best to place the paper on a sandpaper block. Any wood block will do but the patented kinds are very handy. Note Picture 18. Wash the sandpaper out every few minutes with water to remove the accumulation and keep the surface wet. Wash the wood surface off with a sponge and water after finishing the rubbing. A felt rubbing pad on a block of wood makes a good tool over which to stretch the sandpaper. Some finishers stretch the piece of canvas over the felt before putting the sandpaper in place.
¶ These papers are made so fine in grain and so uniform as to composition that they cannot scratch the surface and they do not leave any grit on the surface.
¶ The fineness or coarseness of sandpaper is rated as FF, F, 3/0 (or 000), 2/0 (or 00), 0, ½, 1, 1½, 2, 2½, 3, 3½, 4, 4½. No. FF is the finest and No. 4½ the coarsest.
¶ Most of the sandpaper used by the house painter comes in sheets 9x11 inches or thereabouts. The finer grades used on automobiles, furniture finishing and on interior wood trim of houses is cut into small sheets about the right size to fit the hand. For the sanding of floors it is well to remember that large sheets of sandpaper can be secured for use on a board. A piece of plank about 10x18 inches having a broom handle secured to the center to work like a waxing brush and with a brick or two on top for weight saves a great deal of labor. A large sheet of sandpaper is secured to the board, being lapped over at both ends and fastened with thumb tacks. With such a tool floors are quickly surfaced without working on hands and knees. Note Picture 19.
¶ A ream of sandpaper is 480 sheets single-faced paper of any size, or 240 sheets of double-faced paper.
¶ A quire of sandpaper is 24 sheets, any size.
¶ Sandpaper can be secured also in rolls 50 yards long and from 4 to 28 inches wide. Rolls are used chiefly in factory and millwork as belt sanders.
¶ Steel Wool and Oil. This abrasive is used extensively by the house painter especially and serves the purpose well. It is used both dry and with one of the rubbing oils to keep down the dust and protect the health of the finisher. It is made in the following grades from fine to coarse:
¶ No. 00, - equal to FF pumice stone; No. 0, equal to F pumice stone; No. 1, equal to No. 0 sandpaper; No. 2, equal to No. 7 sandpaper; No. 3, equal to Nos. 1½ and 2 sandpaper; Fine steel shavings; Medium steel shavings; Coarse steel shavings.
¶ Electric Machine Rubbing. In the furniture and automobile factories and in the railway equipment shops much of the rubbing is now being done by machines such as is pictured in Picture 20. These machines do fine rubbing every hour of the day and do not get tired at four o'clock. It is only a question of time until hand rubbing, in the factories at least, is largely superseded by machines. They are already in extensive use. These machine rubbers run by electricity and each has a small motor on it. There are two oscillating pads four or five inches square covered with felt which is, of course, detachable. The pads can also be covered with sandpaper or other grit papers. There are pads for flat surfaces and for curved surfaces. The cost to run such machines is very small. They make no noise, run from ordinary electric light sockets, are light in weight and portable. The operator guides the machine with two hands and no pressure is needed other than the weight of the machine.
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