The early mode of working intarsia in Italy, where it is more than 100 years more ancient than in any other country, was by sinking forms in the wood, according to a prearranged design, and then filling the hollows with pieces of different coloured woods. At first the number of colours used was very small—indeed, Vasari says that the only tints employed were black and white, but this must be interpreted freely, since the colour of wood is not generally uniform, and there would consequently often be a difference in tint in portions cut from different parts of the same plank. A cypress chest of 1350, now in the Victoria and Albert Museum, shows another mode of decoration standing between tarsia proper and the mediÆval German and French fashion of sinking the ground round the ornament and colouring it. In this example the design is incised, the ground cleared out to a slight depth, and the internal lines of the drawing and the background spaces filled in with a black mastic, the result much resembling niello. If dark wood be substituted for the mastic background we have almost the effect of the stalls of the chapel of the Palazzo Pubblico at Siena, which, though an early work of Domenico di NicolÒ, are well considered in design, well executed, and quite satisfactory in point of harmony between material and design.

At the commencement of the Renaissance the fancy of the intarsiatori overflowed in the most graceful arabesques, which are perfectly suited to the material and are often executed with absolute perfection, and these may perhaps be held to be the most entirely satisfactory of their works, though not the most marvellous. The ambition of the craftsman led him to emulate the achievements of the painter, and we find, after the invention of perspective drawing, views of streets and other architectural subjects, which are not always very successful, and the representation of cupboards, the doors of which are partly open, showing objects of different kinds on the shelves, which are often rendered with the most extraordinary realism, when the means adopted are considered.[3] This realism was much assisted by Fra Giovanni da Verona's discovery of acid solutions and stains for treating the wood, so as to get more variety of colour, and by the practice of scorching portions of the pieces of which the subject was composed, thus suggesting roundness by means of shading. It was a common practice to increase the decorative effect by means of gilding and paint, thus obtaining a brilliancy of colour at the expense of unity of effect sometimes, one may think, if one may judge from the panels in the stalls at the Certosa of Pavia—though perhaps it is scarcely fair to take them as examples of the effect of the older work since they have been restored in modern times. At the best period it was used almost entirely for church furniture and the furnishings of public edifices, in Italy at least, and many of the ranges of stalls still occupy their original positions.

The principal woods used in the work of the best period were pear, walnut, and maple, though pine and cypress also appear. Ebony was imitated with a tincture of gall apples, green was obtained with verdigris, and red with cochineal. Sublimate of mercury, arsenical acid, and sulphuric acid were also used to affect the colour of the wood. This treatment lessened its lasting power, and often caused its decay through the attacks of worms. The scorching was done with molten lead, or in very dark places with a soldering-iron. It is now done with hot sand. The following technical description is taken from a German book of 1669—"Wood-workers paint with quite thin little bits of wood, which are coloured in different ways, and the same are put together after the form of the design in hollowed-out panels, fastened with glue and polished with an iron on the surface so that they may become quite smooth. They paint at the present time in this manner tables and jewel chests or trays, and all in the highest artistic manner. Also separate pictures are put together, which copy the works of the most celebrated masters. First, they take small, very thin pieces of pear or lime dyed through with different colour-stuffs, which are prepared by certain processes, so that the wood is the same colour within and without. Then they give them their several shapes as the kind of picture requires, cutting them according to the size and shape, and stick them with glue on the board. In the place of wood they sometimes use bone, horn, and tortoiseshell cut into fine strips, also ivory and silver. The whole work is called by the Germans 'Einlegen' or 'Furnieren,' because although each piece is separate from the others no part is taken out from the surface in which such figures are inlaid, but the whole is covered." With the use of the fret-saw for cutting the patterns, and the consequent discovery of the possibility of counterchanging the ground and the design (that which was black becoming white, and vice versÂ), called male and female forms, the manufacture of tarsia, or marquetry rather, commenced to take a more commercial aspect, the cost being considerably reduced by the making of several copies by one sawing. This is the process used at the present day.

The durability of inlaid work depends upon the tightness and completeness with which the inlaid parts are fitted together or mortised into the main body or bed of the wood, and also on the level grounding out of the matrix. In Spanish and Portuguese work ivory or ebony pins or pegs were used also. Marquetry is a form of veneering, and the operation is thus conducted:—The under surface of the veneer and the upper surface of the bed are both carefully levelled and toothed over so as to get a clean, newly-worked surface; the ground is then well wetted with glue, at a high temperature, and the two surfaces pressed tightly together so as to squeeze as much out as possible. The parts are screwed down on heated metal beds, or between wooden frames, made so as to exactly fit the surfaces in every part, called "cauls," until the glue is hard. In cutting the patterns of Boulle work two or three slices of material, such as brass and tortoiseshell or ebony, are glued together with paper between, so that they may be easily separated when the cutting is done. Another piece of paper is glued outside, upon which the pattern is indicated. A fine watch spring saw is then introduced through a hole in an unimportant part of the design, and the patterns sawn out as in ordinary fretwork. The slices are then separated, and that cut out of one slice is fitted into the others so that one cutting produces several repetitions of the design with variations in ground and pattern. When there are only two slices of material the technical term for them is Boulle and Counter. When the various parts have been arranged in their places, face downwards, paper is glued over them to keep the whole in place, and filings of the material rubbed in to fill up any interstices. The whole is then toothed over and laid down in the same manner as ordinary veneer, the ground being first rubbed over with garlic, or some acid, to remove any traces of grease. Marquetry of wood is made in the same way, but more thicknesses of wood are put together to be sawn through, as many as four not being an unusual number, while for common work even eight may be sawn at one time, and the various sheets are pinned together only with a stiff backing of common veneer of good thickness to steady the work. Dye woods are used as far as possible, and holly stained to the required colour serves for greens and blues and a few other tints. Pearl is always cut in one thickness, and is glued down on a backing of wood at least ?inch thick.

Another mode of cutting the design approximates more nearly to the ancient practice. The whole design is drawn on paper attached to the ground, or counter, and cut out entirely. The various portions of inlay are then cut from different veneers of the desired colour and fitted into their places. Another method is to paste the paper with the whole design on the ground, and on it to paste the various ornaments cut from suitable veneers, then to cut through the ground, the saw grazing the edges of the ornamental forms. The parts so cut out are then pushed through the ornaments, separated from the paper, and laid down in the vacant places. A variation on this method is to cut out the forms to be inlaid in different veneers, and glue them in their proper positions on a sheet of paper. A sheet of white paper is pasted on the veneer, which is to serve as the ground. A sheet of blackened paper is laid over it, and over this the sheet with the forms to be inlaid, which are then struck with a light mallet, so as to print an impression of their edges upon the paper. The printed shapes are then cut out one at a time, care being taken to make the saw exactly follow the outline. The object of all these processes is, of course, to ensure the ground and the inlaid forms exactly fitting. After cleaning the surface from paper and glue it is smoothed with plane and scraper, and the markings on leaves or other figures made by a graver, if not already made by saw cuts, and they and the lines between the male and female forms are filled with shellac or wood-dust and glue.

In Germany the veneers used are one to two millimetres thick, i.e., one-twenty-fifth or two-twenty-fifths of an inch. The principal woods used are walnut, pear, ash, bird maple, holly, olive, amboyna, rose wood, violet wood, thuya, and palisander, which name is also used on the Continent for rose wood and violet, though it is really a sort of cedar. Tortoiseshell, ivory, and metal plates are also used, principally of pewter, brass, and zinc. Seeman's Kunstgewerbliche HandbÜcher advise thus:—"When ivory or hard precious metals are used it is better to divide the design into smaller parts. To avoid damage to the effect by time and change of colour in the woods such combinations as the following are to be preferred:—Mahogany and black walnut, pear and black walnut, Hungarian ash and black thuya, pear and palisander, brass and black, etc. For fine, small ornament smooth, even-textured woods should be used such as pear, mahogany, maple, or holly; for broad patches and backgrounds, which are not required to be dark, you should use patterned or streaked woods, like bird maple, amboyna, thuya, or olive. Ivory, mother-of-pearl, and metals in large pieces look hard and loud, so it is better to use them in quite small pieces. If engraved, larger pieces may be employed and used for inscription tablets, coats of arms, and cartouches, or for bits of figures, birds, and butterflies. Shading may be done in various ways. Lines may be engraved and filled up with a glue cement, or hatchings may be drawn with a scorching solution, or the wood may be burnt with hot sand. The sand is made hot in an iron pot, and the piece to be darkened inserted. Or it may be scorched with a hot iron or spirit or gas flame. The simplest way is with the poker used in poker work." In England the sand is heaped upon a metal plate which is heated underneath. The veneer is held with tweezers and pushed into the sand, the gradation of heat giving gradation of tone. The hot sand shrinks the wood, and allowance must be made for this.

Veneers are both saw and knife cut; the saw wastes about as much as the thickness cut in sawdust. They range from 8 to 15 to the inch. The French saw-cut their veneers thinner than the English do.

The woods in every-day use at the present day are white holly, box, pear (in various shades), and holly (dyed all colours); while the veneer merchants sometimes supply also planetree, sycamore, chestnut, Brazilwood, yellow fustic, barwood, tulipwood, kingwood, East and West India satinwood, rosewood, ebony, ash, harewood, Indian purplewood, hornbeam, and snakewood. Bird's-eye maple and partridgewood may also be bought.

Dye woods used for marquetry—Braziletto, cam wood, logwood, Nicaragua, red sanders, sapan, ebony, fustic (a species of mulberry), Zante (a species of sumach). "Ebony is the black pear tree of Madagascar, at least they make cider of its fruit." So says M. Luchet in an interesting excursus on furniture manufacture in his book on the Paris Exhibition of 1867, in which he gives further details of ancient manufacture and its modern imitation. "I know a factory," he says, "where the tortoiseshell is false, the mother-of-pearl false, the ivory holly wood; the brass is the only real thing, because science applied to industry has not yet found out how to imitate it. When Boulle employed wood in his work it was ebony—they have abandoned that for blackened pear wood, under the pretext that ebony is a hard, close wood which twists, splits, and cracks, takes glue badly, and refuses varnish. So that they call a man who never uses ebony 'ÉbÉniste.' They did not trouble about these things in the time of Louis XIV. They never varnished their furniture, so it did not matter that ebony would not take varnish.... There are two sorts of tortoiseshell, that of the Antilles, often bad and scaly, but good enough for common work, because it is thin and equal in thickness, and a little carmine vermilion gives it a not unpleasant red tint. The Indian tortoiseshell is thick and opaque and unequal, demanding preparation and welding. It can only be used for expensive work, and takes easily a black preparation which makes it magnificently austere." One ought to mention here that good shell was often treated with carmine vermilion or with gold, and that without a colour background it loses half its beauty and value.

"In modern times six or eight couples of shell and metal are sawn together, whereas two was the number in the fine period. This saves money. A new Boulle bed, secretary, or chest of drawers should cost 15 to 20,000 francs. You may easily get one for 2000 made of rubbish. An honest chest of drawers with tolerable mountings is worth 1500 francs. In gelatine tortoiseshell and brass or zinc of the future 100 is the price.... The mode still practised in Paris of making a good 'placage' in preparation for marquetry or Boulle work is as follows:—A thicker or thinner sheet of Italian poplar is placed between two sheets of oak with the grain the other way, then on the external sheet of oak is placed the wood intended to be seen, also with the grain the other way, the whole of convenient thickness, and glued with the best glue. Good glue is the nurse of the wood, say the masters. These four or five thicknesses of wood pulling against each other neutralise all bad effects, and the result is very good. The external covering is usually either mahogany, American walnut, or violet wood (a sort of cedar). Sometimes it is ebony, or perhaps a collection of small pieces of wood, such as acacia, which are called by all sorts of pretty names. It is of this fine and good 'plaquÉ' that they still make cupboards at 1000 francs, beds at 600 francs, and bureaus at 800 francs, which are the success and the pride of Parisian joinery." The marqueteurs of Nice made use of olive for veined grey backgrounds, orange and lemon for pale yellow, carob for dark red, jujube tree for rose colour, holly for white, and charred fig for black; arbutus served for dark flesh, and sumach for light.

It is advisable after the marquetry has been put together to reduce the surface to a level and do something in the way of polishing, though it is not necessary to carry the process as far as is often done by the cheap furniture manufacturers. If nothing but wood has been used, the surface should be reduced to a level with a toothing plane and scraped with a joiner's scraper, taking care to apply it obliquely to the joints as far as possible, so as to avoid digging down and so failing in the object aimed at. If done very well and carefully it sometimes only requires to be rubbed down with its own shavings, but it is more usually necessary to follow with a worn piece of glass-paper on a flat piece of cork, but the dust must not be allowed to collect into hard lumps upon it, as these lumps would scratch the surface. Holtzapffel says that when metal, ivory, pearl, shell, or tortoiseshell are mixed with the wood the surface must be carefully levelled with flat files, ending with a very smooth one, after which the scraper should be used if possible and followed by glass or emery paper very sparingly. When metal preponderates emery paper is best, and really good sand paper may also be used, but all paper should have very little "cut," should be applied dry, and allowed to become clogged, so as to act principally as a hard dry rubber or burnisher. If the polishing is at all in excess the wood will get rubbed or worn down below the metal. The fine finish required when tortoiseshell and metal are used is got by rubbing with blocks of charcoal used endways with oil and the finest rotten-stone powder, much like polishing marble, using oil instead of water. Wet polishing should not be used for inlaid works; the water may soften the glue. A superficial wetting is likely to warp the woods and make them curl up at the edges, and the grain of the wood is almost certain to rise. Oil is better than water, but light woods are almost certain to become stained by polishing powders and fluid. To avoid this modern marquetry is often covered with varnish applied with friction like French polish, or laid on in several coats with a brush and polished off with pumice and rotten stone, like the Vernis Martin, being first levelled with a file or scraper and smoothed with glass-paper.