Part 483

Some tried formulas follow:

I.—Make a paste to fill the cracks as follows: Old furniture polish: Whiting, plaster of Paris, pumice stone, litharge, equal parts, Japan drier, boiled linseed oil, turpentine, coloring matter, of each a sufficient quantity.

Rub the solids intimately with a mixture of 1 part of the Japan, 2 parts of the linseed oil, and 3 parts of turpentine, coloring to suit with vandyke brown or sienna. Lay the filling on with a brush, let it set for about 20 minutes, and then rub off clean except where it is to remain. In 2 days it will be hard enough to polish. After the surface has been thus prepared, the application of a coat of first-class copal varnish is in order. It is recommended that the varnish be applied in a moderately warm room, as it is injured by becoming chilled in drying. To get the best results in varnishing, some skill and experience are required. The varnish must be kept in an evenly warm temperature, and put on neither too plentifully nor too gingerly. After a satisfactorily smooth and regular surface has been obtained, the polishing proper may be done. This may be accomplished by manual labor and dexterity, or by the application of a very thin, even coat of a very fine, transparent varnish.

If the hand-polishing method be preferred, it may be pursued by rubbing briskly and thoroughly with the following finishing polish:

Alcohol 8 ounces Shellac 2 drachms Gum benzoin 2 drachms Best poppy oil 2 drachms

Dissolve the shellac and gum in the alcohol in a warm place, with frequent agitation, and, when cold, add the poppy oil. This may be applied on the end of a cylindrical rubber made by tightly rolling a piece of flannel, which has been torn, not cut, into strips 4 to 6 inches wide. It should be borne in mind that the surface of the cabinet work of a piano is generally veneered, and this being so, necessitates the exercise of much skill and caution in polishing.

II.—Prepare a paste from fine starch flour and a thick solution of brown shellac, with the spatula upon a grinding stone, and rub the wooden object with this. After the drying, rub off with sandpaper and polish lightly with a rag moistened with a thin shellac solution and a few drops of oil. The ground thus prepared varnish once or twice and a fine luster will be obtained. This method is well adapted for any wood with large pores, such as oak.

«Removal of Heat Stains from Polished Wood.»—Fold a sheet of blotting paper a couple of times (making 4 thicknesses of the paper), cover the place with it, and put a hot smoothing iron thereon. Have ready at hand some bits of flannel, also folded and made quite hot. As soon as the iron has made the surface of the wood quite warm, remove the paper, etc., and go over the spot with a piece of paraffine, rubbing it hard enough to leave a coating of the substance. Now with one of the hot pieces of flannel rub the injured surface. Continue the rubbing, using freshly warmed cloths until the whiteness leaves the varnish or polish. The operation may have to be repeated.

«PRESERVATION OF WOOD.»

I.—An excellent way of preserving wood is to cut it between August and October. The branches are removed, leaving only the leaves at the top. The trunks, carefully cut or sawn (so that their pores remain open), are immediately placed upright, with the lower part immersed in tanks three-quarters filled with water, into which 3 or 4 kilograms of powdered cupric sulphate per hectoliter have been introduced. The mass of {777} leaves left at the extremity of each trunk is sufficient to cause the ascent of the liquid by means of the capillary force and a reserve of energy in the sap.

II.—Wood which can be well preserved may be obtained by making a circular incision in the bark of the trees a certain time before cutting them down. The woodcutters employed in the immense teak forests of Siam have adopted in an empirical way a similar process, which has been productive of good results. The tree is bled, making around the trunk, at the height of 4 feet above ground, a circular incision 8 inches wide and 4 inches deep, at the time when it is in bloom and the sap rising. Sometimes the tree is left standing for 3 years after this operation. Frequently, also, a deep incision reaching the heart is made on two opposite sides, and then it takes sometimes only 6 months to extract the sap.

It is probable that it is partly in consequence of this method that the teakwood acquires its exceptional resistance to various destructive agents.

III.—A good preservation of piles, stakes, and palisades is obtained by leaving the wood in a bath of cupric sulphate of 4° of the ordinary acidimeter for a time which may vary from 8 to 15 days, according to greater or less dryness of the wood and its size. After they are half dried they are immersed in a bath of lime water; this forms with the sulphate an insoluble compound, preventing the rain from dissolving the sulphate which has penetrated the wood. This process is particularly useful for vine props and the wood of white poplars.

A good way to prevent the decay of stakes would be to plant them upside down; that is, to bury the upper extremity of the branch in the ground. In this way, the capillary tubes do not so easily absorb the moisture which is the cause of decay. It frequently happens that for one or another reason, the impregnation of woods designed to be planted in the ground, such as masts, posts, and supports has been neglected. It would be impracticable, after they are placed, to take up these pieces in order to coat them with carbolineum or tar, especially if they are fixed in a wall, masonry, or other structure. Recourse must be had to other means. Near the point where the piece rises from the ground, a hole about one centimeter in width is made in a downward slanting direction, filled with carbolineum, and closed with a wooden plug.

It depends upon the consistency of the wood whether the liquid will be absorbed in 1 or 2 days. The hole is filled again for a week. The carbolineum replaces by degrees the water contained in the wood. When it is well impregnated, the hole is definitely closed with a plug of wood, which is sawn level with the opening. The wood will thus be preserved quite as well as if it had been previously coated with carbolineum.

IV.—Wooden objects remaining in the open air may be effectually protected against the inclemency of the weather by means of the following coating: Finely powdered zinc oxide is worked into a paste with water and serves for whitewashing walls, garden fences, benches, and other wooden objects. After drying, probably at the end of 2 or 3 hours, the objects must be whitewashed again with a very dilute solution of zinc chloride in glue or water. Zinc oxide and zinc chloride form a brilliant, solid compound, which resists the inclemency of the weather.

As a paint for boards, planks for covering greenhouses, garden-frames, etc., Inspector Lucas, of Reutlingen (Würtemberg), has recommended the following coating: Take fresh cement of the best quality, which has been kept in a cool place, work it up with milk on a stone until it is of the consistency of oil paint. The wood designed to receive it must not be smooth, but left rough after sawing. Two or 3 coats are also a protection from fire. Wood to be thus treated must be very dry.

V.—Wood treated with creosote resists the attacks of marine animals, such as the teredo. Elm, beech, and fir absorb creosote very readily, provided the wood is sound and dry. Beechwood absorbs it the best. In fir the penetration is complete, when the wood is of a species of rapid growth, and of rather compact grain. Besides, with the aid of pressure it is always possible to force the creosote into the wood. Pieces of wood treated with creosote have resisted for 10 or 11 years under conditions in which oak wood not treated in this way would have been completely destroyed.

The prepared wood must remain in store at least 6 months before use. The creosote becomes denser during this time and causes a greater cohesion in the fibers. In certain woods, as pitch pine, the injection is impossible, even under pressure, on account of the presence of rosin in the capillary vessels.

VI.—M. Zironi advises heating the wood {778} in vacuo. The sap is eliminated in this way. Then the receiver is filled with rosin in solution with a hydrocarbide. The saturation takes place in two hours, when the liquid is allowed to run off, and a jet of vapor is introduced, which carries off the solvent, whole the rosin remains in the pores of the wood, increasing its weight considerably.

VII.—Wood can be well preserved by impregnating it with a solution of tannate of ferric protoxide. This method is due to Hazfeld.

VIII.—The Hasselmann process (xylolized wood), which consists in immersing the wood in a saline solution kept boiling under moderate pressure, the liquid containing copper and iron sulphates (20 per cent of the first and 80 per cent of the second), as well as aluminum and kainit, a substance until recently used only as a fertilizer, is now much employed on the railways in Germany.

IX.—Recently the discovery has been made that wood may be preserved with dissolved betuline, a vegetable product of the consistency of paste, called also birchwood rosin. Betuline must first be dissolved. It is procurable in the crude state at a low price. The wood is immersed for about 12 hours in the solution, at a temperature of from 57° to 60° F.

After the first bath the wood is plunged into a second, formed of a solution of pectic acid of 40° to 45° Bé., and with a certain percentage of an alkaline carbonate—for instance, potassium carbonate of commerce—in the proportion of 1 part of carbonate to about 4 parts of the solution. The wood remains immersed in this composition for 12 hours; then it is taken out and drained from 8 to 15 hours, the time varying according to the nature of the wood and the temperature. In consequence of this second bath, the betulin which was introduced through the first immersion, is fixed in the interior of the mass. If it is desirable to make the wood more durable and to give it special qualities of density, hardness, and elasticity, it must be submitted to strong pressure. In thus supplementing the chemical with mechanical treatment, the best results are obtained.

X.—A receiver of any form or dimensions is filled with a fluid whose boiling point is above 212° F., such as heavy tar oil, saline solutions, etc. This is kept at an intermediate temperature varying between 212° F. and the boiling point; the latter will not be reached, but if into this liquid a piece of wood is plunged, an agitation analogous to boiling is manifested, produced by the water and sap contained in the pores of the wood. These, under the action of a temperature above 212° F., are dissolved into vapor and traverse the bath.

If the wood is left immersed and a constant temperature maintained until every trace of agitation has disappeared, the water in the pores of the wood will be expelled, with the exception of a slight quantity, which, being in the form of vapor, represents only the seventeen-hundredth part of the original weight of the water contained; the air which was present in the pores having been likewise expelled.

If the liquid is left to cool, this vapor is condensed, forming a vacuum, which is immediately filled under the action of the atmospheric pressure. In this way the wood is completely saturated by the contents of the bath, whatever may be its form, proportions or condensation.

To attain the desired effect it is not necessary to employ heavy oils. The latter have, however, the advantage of leaving on the surface of the prepared pieces a kind of varnish, which contributes to protect them against mold, worms, moisture, and dry rot. The same phenomenon of penetration is produced when, without letting the wood grow cold in the bath, it is taken out and plunged immediately into a cold bath of the same or of a different fluid. This point is important, because it is possible to employ as fluids to be absorbed matters having a boiling point below 212° F., and differing in this respect from the first bath, which must be composed of a liquid having a boiling point above 212° F.