Having already stated the most approved methods of seasoning wood, under the article Timber, we shall at present direct our attention woo tention to the most advantageous expedients that have been devised for preserving this useful substance; and conclude with an account of the best modes of imparting to it different colours.
To render timber more durable, it has been recommended to saw the trees into scantlings ; or, where the wood is designed to be used entire, to hew it into the requisite shape; when it is to be laid in a bed of sand (contained in a case or shell of brick-work) and heated by-means of a furnace, built beneath. As soon as the wood becomes hot, the sap exudes, and is imbibed by the sand; in consequence of which, the quality of the timber is greatly improved. This method has been successfully tried ; but, as it is too expensive, Dr. Lewis advises all wood, that is exposed to the inclemency of the weather, to be coated with a preparation of pulverized pit-coal and melted tar, reduced to the consistence of paint, which he has found very efficacious. In those cases, however, where piles, or other masses of timber, are subject to the action of water, the most simple mode of preserving it, is that employed in the Bermuda Islands, and other parts of America. It consists in covering such wood repeatedly with , train or whale-oil, allowing each coat to become perfectly dry, before another is applied. - For preventing the combustion of wood, the reader will consult the article Fire-Proof.
Mahogany, ebony, and the finer woods, being very expensive, artisans have contrived various preparations for tinging timber, so as to be with difficulty distinguished from them. Thus, ebony may be imitated, by boiling clean, smooth box in oil, till it become perfectly black; or, by washing pear-tree wood, that has been previously planed, with aqua-fortis, and drying it in a shady place, in the open air; after which, writing-ink must repeatedly be passed over it, and the wood dried in a similar manner, till it acquire a deep black colour. It may then be polished with wax and a woollen cloth, which will give it a fine lustre.
In the new " Transactions of the Royal Society of Gottingen, " Prof. Beckmann has published the result of numerous experiments, relative to the staining or dyeing of wood. He directs, for instance, a piece, of plane-tree to be put into a glass vessel, containing pulverized dragon's-blood mixed with oil of turpentine, and placed over the fire : in a short time, the wood will acquire a beautiful colour, resembling that of mahogany; and the dragon's-blood, adhering to the surface, may be separated by applying rectified spirit of wine. If gamboge be dissolved in spirit of turpentine, it will impart a bright-yellow colour; and one part of dragon's-blood, with two of gamboge, communicate various shades to the wood of the beech and plane-trees. A fine walnut-tree tint may be obtained, by rubbing common wood with a mixture, prepared of the bark of the trees, or the shells of walnuts, previously dried, pulve-rized, and reduced to a proper consistence with nut-oil.
Another preparation for communicating a perfect mahogany-colour to inferior woods, especially those of the elm, maple, and sycamore-trees, consists of the following ingredients : Dissolve two drams of dragon's-blood, one dram of wild alkanet (Anchusa tinctoria, L.), and half a dram of aloe, in half a pint of rectified spirit of wine. Previously to using this tincture, the 1 ought to be moistened with aqua-fortis; when two or three coats of the former, each being allowed to dry before the next is applied, will be sufficient to produce the desired effect.
In March, 1778, a patent was granted to Mr. HumPHREY Jackson, for his method of beautifying, and preserving the colour of every kind of wood, by means of a stain, varnish, and powder. He directs the substance first to be polished with the following composition : - Take pumice-stone and burnt alum, of each equal parts; lapis calami -naris, and green-vitriol calcined to redness, of each half a part; let the whole be reduced to a fine powder, and rubbed with a woollen cloth on the wood, till it acquire a fine polish: the stain must now be prepared as follows: - Let 61bs. of stick-lac be boiled in three gallons of water, till the colour be extracted, when the liquor ought to be strained : half a pound of madder-root is also to be boiled in three quarts of water : next, half a pound of cochineal, a similar quantity of kermes, and 4 oz. of clean scarlet-rags, are to be digested in a glass vessel, containing one gallon of spirit of wine, and a solution of 2 oz. of pearl-ash in half -a pint of water, till all the tinging matter be combined with the liquor. After straining it, the decoction of stick-lac must be added, and a sufficient quantity of aquafortis be mixed with the whole, to impart a proper red colour ; when the compound may be laid on with a brush. - In order to prepare the varnish, the patentee directs one pound of clear white amber, half a pound of copal, a similar quantity of spirit of turpentine, as well as of the oils of rosemary, and lavender ; and six pounds of nut-oil, to be digested in a sand-heat, till the oils acquire the consistence of syrup : the liquor is now to be strained for use ; and, when the varnish becomes clear, it must be applied to the stained wood with a painter's brush ; after which it should be suffered to dry.
A patent was likewise granted, in November, 1791. to Samuel Bentham, Esq. for his invention of a method of planing wood. - Our limits will not admit of an analysis of his diffuse specification : we shall therefore only state that, by his contrivance, the operation of planing is simplified to such a degree that animals, steam, water, machinery, and other brute or inanimate agents, may be advantageously employed. - A minute account of his patent is inserted in the 5th vol. of the " Repertory of Arts, '' etc.
Various other methods of staining wood blue, green, purple, red and yellow, are practised by artificers. Of these, we shall communicate only the most expeditious, and least expensive.
Blue: - Take 2 drams of the best indigo reduced to a fine powder; put it in a glass with 2 oz. of oil of vitriol, and agitate them with a new clay-pipe. - After standing 10 or ; 2 hours, at the farthest, in a temperate place, pour it into a large glass vessel, or china bowl, and add such a portion of pure water as may be expedient to give it the tint required. - Those, to whom the saving of time is an object, may purchase this staining liquor ready prepared, from the. dyer. Another mode of tinging wood wood blue, is that of dissolving verdigrease in distilled vinegar; then making a separate solution of 2 oz. of pure pearl-ashes in a pint of water : the former liquid should be first repeatedly applied to the surface of the wood, till it be of a sufficiently deep green colour; when the latter preparation must be drawn over it, with a soft • painter's brush, as often as may be necessary to change it to a proper blue cast.
Green : - Dissolve purified verdigrease in distilled vinegar, or in aqua-fortis diluted with 15 or 20 times its weight of water, and apply the solution to wood previously warmed.
Purple : - Take 1 oz. of logwood, and 2 drams of Brazil-wood; boil them together in a quart of water, slowly, over a moderate fire : when one-half of the fluid is evaporated, it must be strained, and several times laid on the wood, with a proper brush, till it have received a dark-red shade. Thus prepared, and being allowed to become perfectly dry, it may be changed to a fine purple shade, by drawing over it repeatedly a weak solution of the purest pearl-ash, namely, one dram in a pint of water. Some dexterity, however, must be exerted on this occasion ; as, by too sudden and frequent applications of either of the two liquids, the colour is very apt to assume a dark blue, instead of a purple shade.
Red : - Take 2 oz. of Brazilwood, and 2 drams of purified pot-ash; mix them with a quart of water; and let the composition stand in a warm place for several days ; stirring it occasionally. - When sufficiently extracted, the coloured liquor must be decanted moderately warmed, and in that state applied to the wood as many times as may be deemed necessary for giving it a more or less bright cast. Next, a solution of alum, in the proportion of 2 oz. to a quart of water, is to be laid on the wood (while it is still wet from the former stain) with a soft brush, or other instrument. - After polishing the articles thus stained, their colour may be rendered still more beautiful and permanent, by giving them one or more coats, with a varnish prepared of shell-lac.
Yellow : - This delicate tint may be easily imparted to wood, which is naturally white : for this purpose, take 1 oz. of pulverized turmeric, and a pint of rectified spirit of wine; shake them in a glass bottle; allow the infusion to stand for several days, closely covered : then decant the liquor, and lay it on the wood repeatedly, as may be found necessary. - A cheaper method, however, consists in applying weak aqua-fortis to wood previously warmed, and immediately after the stain is given, holding it to the fire, at some distance, till it acquire the desired cast. But it should be remarked, that the aqua-fortis must be suffi-ciently diluted with water; as, otherwise, the wood is apt to ac-quire a brown or blackish hue. In, order to improve the articles thus stained, the same expedients may be adopted, as those suggested in the preceding paragraph.
To conclude: - As it is frequently an object of some importance, to close and secure the chinks, flaws, or other accidental detects in wooden vessels, in the most expeditious manner, we conceive that a tough paste, composed of whiting, a solution of gum-arabic or tragacanth, and a proper quantity of oak-bark reduced to a fine powder, may be advantageously applied to tubs or casks, with a view to prevent farther leaking. But, on such occasions, it will always be more advisable to empty the vessels ; and, after drying them, to use A cement, consisting of pitch, bullocks blood, linseed-oil, turpentine, and the finest brick-dust, melted together in an iron pan : before, however, this powerful lute be laid on, all the crevices or chinks ought to be properly caulked, or filled up with tow or oakum.