Like solid wood, most veneers are reckoned by the superficial foot, burrs being generally sold at so much each.
Veneers are laid, that is, glued to the solid backing, by two methods, viz., with the caul or with the hammer.
Caul laying is the better, though more troublesome, of the two processes, and may be described first. With it the veneer and ground are kept in close contact by pressure till the glue has hardened, so that they are as firmly joined as possible if the work is done properly. The cauls are simply pieces of wood or metal which fit exactly to the veneered surface. It is rarely that the cabinet-maker requires to use any but flat cauls, as it is seldom that a curved surface has to be veneered. If he should meet with any, if he understands flat work, he will have no difficulty in knowing how to act. In order, therefore, to make the explanation of the process as clear as possible, it may for the present be assumed that only flat surfaces have to be veneered.
Wooden cauls have been generally displaced in well-appointed shops, where much veneering is done, in favour of metal, but for occasional use they do very well, the principal advantage of metal being that it is more durable. There are, however, disadvantages attending its use, and many consider that the wooden caul is preferable, so that the novice or amateur has no occasion to use anything else. The caul is merely a piece of wood of, say, an inch thick, of such a size as will cover the veneer. Pine does as well as anything, and a nice clean piece which is not likely to twist should be selected. It may be worth while noting that wood which has been used for a caul may be employed for working up afterwards. Its use as a caul will, at any rate, have made it thoroughly dry. Generally, however, the cauls are kept as such, but on occasion any piece of wood may act as a temporary caul without being destroyed for other purposes.
For metal cauls sheets of zinc are generally used, as being the most suitable. The thickness is not of importance, and for ordinary purposes may be anything from 1/4 in. to 1/8 in., or even less, as it is advisable to use it in conjunction with a wooden backing or caul in most cases. The advantage of metal over wood consists principally in its durability, as it is not so apt to be destroyed by careless heating; but with ordinary care there is no reason why a wooden caul should be burnt. Perhaps the chief objection to a metal caul, especially when used by a novice, is that it may be made too hot for the work without being destroyed. A wooden one may be made too hot, but in keeping it from being charred the beginner is not likely to make it so. In competent hands the work can be done equally well with either wood or metal, and extreme nicety in the degree of heat is not important. But this will be referred to later on.
The treatment or preparation of veneers is simple; in fact, beyond having them thoroughly dry before beginning to lay them, little need be said about most of them. If they are kept in stock, to prevent them splitting when moved about, the ends should be covered with paper, or cotton, or something of the kind glued over them. Burr veneers being very much twisted, require flattening out before they can be laid. The best way to treat them is to damp them till they are sufficiently pliable, and then put them between two heated boards or cauls, pressure being exerted by hand-screws. When dry, they will be flat, but before they can be laid the holes and imperfections must be filled up, and to do this properly is a troublesome job sometimes. Burr walnut veneers, it may be well to explain, are full of irregular holes and cracks, and in their original state have very little indication of their beautiful appearance when laid and polished. The holes are of such a kind that they cannot be filled by simply stopping them up, for it is generally necessary to cut away some of the surrounding wood and let another piece in. To ensure an accurate fit, two pieces may be sawn through together with an ordinary small fret-saw, and in doing this care should be taken that the inlaid piece matches as nearly as possible to the figure of the surrounding wood. By sawing an irregularly shaped piece to correspond with the markings of the wood, the joint will in the finished veneer scarcely be observable. When the work has been really well done, it is often almost impossible, even with close examination, to discover the pieces which have been let in. I suppose it is hardly necessary to say that an entire sheet need not to be cut up to supply the small inlet pieces, as small bits of odds and ends will do very well for them. As they are cut, fit them in to the holes, and glue pieces of paper over to hold them in. If the veneers are choice, no pains should be spared over this part of the work, as nothing looks worse than to see a fine veneered surface marred by pieces let in so conspicuously that one cannot help noticing the inlaid bits.
Any veneer which may be twisted and require flattening may be treated between cauls after having been previously damped. With rosewood, however, it is better to warm it instead of damping. It should be held near the fire till the oil or resin exudes, and then placed under pressure till cold. Even if already sufficiently flat, it is often considered necessary to heat it, in order to get rid of some of the resin it contains. This applies especially to those kinds which contain much resin.
Whenever veneer has been damped, it is necessary to be very careful to see that it is thoroughly dry before laying. As much care should be taken with all veneers in this respect as with solid wood.
Before the veneer is laid, any saw marks should be removed with the toothing plane, which at the same time roughens the surface slightly and affords a good hold for the glue. The surface of the groundwork should be prepared in the same way, for if left unplaned, the saw marks will be observable through the veneer. In fact, the wood should be prepared as carefully as if it were not to be veneered, and also be toothed. Knife - cut veneers having no saw marks, may be laid just as they are; indeed, they are so thin that they would not stand toothing.