This section is from the book "Spons' Mechanics' Own Book: A Manual For Handicraftsmen And Amateurs", by Edward Spon. Also available from Amazon: Spons' Mechanics' Own Book.
Inlaying is a term applied to work in which certain figures which have been cut out of one kind of material are filled up with another. Such work is known as marquetry, Boule work, or Reisner work. The simplest method of producing inlaid work in wood, is to take 2 thin boards, of wood, or veneers, and glue them together with paper between, so that they may be easily separated again. Then, having drawn the required figures on them, cut along the lines with a very fine, hair-like saw. This process is known as counterpart sawing, and by it the pieces removed from one piece of wood, so exactly correspond with the perforations in the other piece, that when the two are separated and interchanged, the one material forms the ground and the other the inlay or pattern. If the saw be fine and the wood very dry when cut, but afterwards slightly damped when glued in its place, the joint is visible only on very close inspection, and then merely as a fine line. After being cut, the boards or veneers are separated (which is easily done by splitting the paper between them), and then glued in their places on the work which they are to ornament.
A new method of inlaying is as follows: - A veneer of the same wood as that of which the design to be inlaid consists - say sycamore - is glued entirely over the surface of any hard wood, such as American walnut, and allowed to dry thoroughly. The design is then cut out of a zinc plate about 1/20 in. in thickness, and placed upon the veneer. The whole is now subjected to the action of steam, and made to travel between 2 powerful cast-iron rollers 8 in. in diameter by 2 ft. long, 2 above and 2 below, which may be brought within any distance of each other by screws. The enormous pressure to which the zinc plate is subjected forces it completely into the veneer, and the veneer into the solid wood beneath it, while the zinc curls up out of the matrix it has thus formed and comes away easily. All that now remains to be done is to plane down the veneer left untouched by the zinc until a thin shaving is taken off the portion forced into the walnut, when the surface being perfectly smooth, the operation will be completed.
It might be supposed that the result of this forcible compression of the woods would leave a ragged edge, but this is not the case, the joint being so singularly perfect as to be inappreciable to the touch; indeed, the inlaid wood fits more accurately than by the process of fitting, matching, and filling up with glue, as is practised in the ordinary mode of inlaying.