Embossing. When a raised pattern is produced by blows or pressure upon sheet-metal, leather, cloth, paper, gutta-percha, &c., it is said to be embossed. A vase or dish formed of thin sheet-metal is sometimes decorated in relief by beating it up from the inner or under side. This operation is called beating up, bossing, or repoussé, and may be considered as an example of embossing by hand. A somewhat similar result is obtained by the use of a die and counter-die worked in a screw-press or by a falling weight, but this is usually called stamping (see DIE-SINKING, and STAMPING OF METALS). The term embossing is not applicable to decoration in relief produced by carving or chiselling, or by casting. Writing-paper and card are embossed with a steel die, the counter-die being formed of millboard or leather, faced with gutta-percha. The paper or card is damped, and a fly-press or lever-press is generally used.
Leather is embossed in several ways. For book-covers, even in the case of patterns in comparatively bold relief, like those used for photographic albums, brass dies and millboard counter-dies are used along with a lever or screw-press (see BOOK-BINDING). When for other purposes the ornament is to be in high relief, moulds or reverses of metal or wood are required, or separate ornaments of wood or papier-maché, fixed to a board, may be used. The leather is first softened with water, and then pressed with tools of various kinds into the moulds, or spread over the fixed ornaments, and worked into all their cavities with the fingers and a pointed tool. The hollows of the more deeply relieved portions are filled in with paper pulp and other substances.
At the present time, imitations of embossed leather for wall-decoration are very much in fashion. These are made of canvas, leather, paper, and various other substances. Even so fine a material as satin is embossed for this purpose. Embossed linen canvas made of a durable nature is coming much into use for decorative purposes. It is manufactured by passing the damped canvas over a metal roller, heated internally with steam, upon which the pattern is cut or engraved in intaglio. As the web passes over the roller, brushes or pads are applied to press the canvas into the indentations. By means of additional rollers, a backing of paper is pasted on, and when the whole is dry it is stiff and retains its shape. Japanese wall-papers, which are embossed in a somewhat similar manner to the linen canvas just described, but by the use of flat instead of cylindrical moulds, are now a good deal used in England. The patterns are often beautiful, the paper is strong, and the surface is made durable by coatings of oil and lacquer. Embossed canvas, paper, and leather for wall-decoration are commonly coloured and gilt.
Calicoes and other textiles are embossed by means of deeply engraved metal cylinders fitted into calender frames. The counter-roller is covered with felt, which yields sufficiently to allow the fabric to be pressed into the hollows of the die-cylinder. Sometimes the pattern is on two cylinders, being sunk on the one and raised on the other, after the plan of a die and its counterpart.
There is a method of embossing wood by saturating it with water, in which state a red-hot cast-iron mould is forcibly pressed upon it. Generally the wood is re-wetted, the mould re-heated, and the pressure applied several times before a complete impression of the mould is obtained. A curious mode of embossing wood was invented about 1830 by J. Straker. The design is drawn upon the surface to be thus decorated, and all the parts intended to be in relief are then carefully depressed by a blunt tool. The wood is next planed down to the level of the depressed portions. On being steeped in water, these will rise to their former level, forming an embossed pattern ready, when the wood is dry, to receive the finishing-touches of the carver. By a process recently invented in America, veneers of wood are embossed with metal dies. See DIE-SINKING.
The process of etching ornamental patterns with hydrofluoric acid on plate-glass, for the panels of lobby-doors, &c., is called 'embossing.'