The tortoiseshell boxes usually made in England are those which are veneered upon a body or fabric of wood, for which purpose the plates are scraped and filed to an uniform thickness, and glued on much the same as veneers of wood; generally fine glue is the only cement used, but various compositions are resorted to by different manufacturers. To improve the appearance of the shell, and to conceal the glue and wood beneath, the back of the veneer is rubbed with a mixture of lamp-black, vermilion, green, chrome, or white; in fish glue, the colours are applied over the entire surface, or partially, to modify the effect, and thus prepared the veneers are glued upon the boxes.
*The reader will find details of the methods of making all these kinds of boxes the Manuel du Tourneur, 1816, vol ii. pp. 460 - 177. And in Gill's Tech. Repos., 1827, p. 336, the apparatus of a wholesale manufacturer of the boites de drogues, since established in the Brazils, is minutely explained.
In tortoiseshell works inlaid with mother-of-pearl and gold or silver plates or wire, the substances to be inlaid are first prepared, and for pearl-shell a paper is pasted on a thin piece of pearl; the pattern is drawn thereupon, and the small pieces are cut out with a fine buhl saw; gold and silver plates are sometimes also thus sawn out.
A plain mould similar to fig. 39, but rectangular, and with plain dies, as c and e, is used; a few shavings of tortoiseshell are first placed on the piece c, to make a bed or cushion, then a piece of paper to prevent them from adhering to the thin leaf of tortoiseshell, which is next inserted in the mould. The small pieces of pearl-shell, etc. to constitute the pattern, are then carefully arranged in their intended positions, and the top plate e is very carefully lowered into the mould above the pieces, so that it may not misplace any of them. The mould is then slid into the press, slightly squeezed, and plunged into the copper for an hour, carried to the bench and screwed moderately tight; the work is now examined to see that nothing is misplaced, it is returned to the cauldron for a time, and the final squeeze is given by the entire force of three men, after which, whilst still under pressure, the whole is plunged into the cold water. The tablet is then fit to be smoothed and glued on the wooden box.
It will be readily conceived, that the force required depends upon the dimensions of the work: pieces of three or four inches square require all the appliances described; whereas the little shields, or escutcheons, as they are called, upon razors and knives may be pressed in with much slighter apparatus, such in fact as were previously described as being used in moulding them. In cutlery, a different method is generally resorted to, which applies equally well to ivory and pearl-shell, substances which cannot be submitted to the softening and moulding processes employed for horn and tortoiseshell.
The cutlery works which are dotted all over with little studs of gold or silver, are drilled from thin patten plans of brass or steel in which the series of holes have been carefully made; the drill or passer" has an enlargement or stop, which, by encountering the surface of the pattern-plate, prevents the point of the drill from penetrating beyond the assigned depth into the handle; the holes in the ivory or pearl-shell arc then filled with silver or gold wire, which is either filed and polished off level with the general surface, or allowed to project as little studs.
For shields and escutcheons they use pattern plates or templets of hardened steel, pierced with the exact form of the shield. The cutting tool somewhat resembles an ordinary breast-drill eight or ten inches long, and like it, is used with the breastplate and drill-bow; but the extremity of the tool is cleft, or made in two branches,whichleft to themselves spring open to the extent of an inch or more; each half of the tool has a shoulder or stop, which bears upon the surface of the steel guard-plate, as in the drill, and a rectangular cutting part that protrudes through the shield-plate as far as the required depth of the recess, and is sharpened both at the end and side, or at the ends only.
When the elastic tool, or "spring passer," has been compressed, so as to enter the guard-plate, it is put in motion, and flounders about in all directions, so far as it can expand, and routs or cuts out the shallow recess; the escutcheons are punched out, fixed by two rivets, and smoothed off; these processes arc very expeditious, and produce accurate copies of the respective pattern-plates employed. The tortoiseshell when unnecessarily thick for a single scale for a penknife, is sawn to serve for two; and the colours are brightened up by placing a piece of Dutch leaf beneath the same; they are finally polished on the various wheels used by the cutler, as will be explained in the pages of the next volume, devoted to polishing. Tortoiseshell has been manufectured into hollow walking-sticks, and in 1811 Her Majesty was graciously pleased to present to the British Museum a tortoiseshell bonnet, made in Navigator's Island.