Chapter IV

. It then only remains to give the finishing touch to the work by passing a polishing iron (Fig. 32) over the surface, to polish it and make it perfectly even. The tool is heated by holding the part which does not come in contact with the leather over the flame of a spirit-lamp. The polished side should frequently be well rubbed on flannel, and should any portion of its surface become dull, the polish can be restored with fine emery paper. The polishing iron, when heated, is held in the right hand and worked with little stroking movements, bringing first the end and then, by lowering the handle, the back of its polished surface in contact with the leather. The various positions of the tool during this operation closely resemble those of a vessel when it is pitching.

[Illustration: 10. COVER OF WORK-BOX OF WOOD COVERED WITH EMBOSSED LEATHER, _CUIR BOUILLI_. GERMAN, 16TH CENTURY.]

[Illustration: 11. POWDER-FLASK OF WOOD COVERED WITH LEATHER, _CUIR BOUILLI_, CUT AND EMBOSSED. ITALIAN, 16TH CENTURY.]

POLYCHROME MOSAIC

[Illustration: FIG. 32.——POLISHING MOSAIC]

This style of decoration consists of different coloured leathers arranged upon a ground, and is the only one that can properly be called leather mosaic. The work of marking it out is a lengthy one and demands scrupulous exactitude. A finished design is first painted in water-colours and marked with letters which are repeated on the pieces of coloured leather, so that the exact place is indicated which they are to occupy in the design. It is important in this style of mosaic to obtain a very correct tracing of the design on the groundwork. On a smooth and light ground the tracing-point lightly worked will be sufficient; when the ground is dark or has a grained surface, red or white transfer paper should be used. The most satisfactory method of marking the design is by impressing a stencil of thick paper, but it cannot be employed with morocco leather for fear of crushing the grain too much. A thick stencil, however, carefully used without exerting great pressure, may give a sufficient result without spoiling the grain.

For polychrome mosaic on a smooth ground with an inlay of split sheepskin pasted on Canson paper, the method already described for working mosaic of one colour is the best, but at the same time the directions which are given below for placing the differently coloured skins side by side in position should be followed.

POLYCHROME MOSAIC ON A MOROCCO GROUNDWORK

Morocco leather for inlaying is thinned with the paring-knife, but it cannot be reduced to the excessive thinness of split sheepskin. It possesses, however, the advantage that the extreme edges may be made thinner in proportion for laying one over the other at the point where they meet.

After it is pared, the back of the leather is pasted over and it is pinned out on a board to dry. The different parts of the design to be inlaid are then traced on the various coloured leathers, and cut out in the manner already explained. The difficulty of placing the pieces exactly edge to edge is so great that it is better to allow them to overlap very slightly, but in order that this should not produce undue thickness at the point where they join, the substance of the extreme edges must be further reduced with the paring-knife. A small margin is left for this purpose in cutting out. Paring the edges to their thinnest possible substance will give a slightly jagged outline, and the extra piece will thus more easily merge into the join than if sharply cut. Outlining with the hot tool will perfect the join.

PASTING THE INLAY ON A MOROCCO GROUNDWORK

To avoid crushing the grain of rough morocco, the tool illustrated in Fig. 33 is used instead of the roller to secure the adhesion of the inlay to the groundwork, in order that the pressure may be applied only upon the inlay. Damping the groundwork, except where the ornament is placed, should be avoided. The tool is held pressed down with both hands as in Fig. 34, and rubbed backwards and forwards. The work is then placed under boards.

MOSAIC ON MODELLED LEATHER

The remarks on paring leather for polychrome mosaic apply also to paring the leather for covering a design in relief. An extra margin is left round the edges, which are “slashed” with the tool, so that they may better embrace the form of the modelling, the finer details of which are not worked until afterwards. The leather is first placed dry in position over the modelling, and smoothed over with a modeller, so that it takes the form of the relief. It will then be seen how much should be cut from the edges, so that it may exactly fit into the outline when it is pasted on.

INSERTED MOSAIC

This method of mosaic invented by Mons. Aumaître possesses the advantage of being very durable, owing to the edges of the inlay being secured between the two edges of the incision made in the groundwork. The outline is deeply cut in the groundwork, the incision well opened with the opener and then filled with paste. The inlay is also pasted and the edges inserted in the incision. A wheel or a large modeller is used to press down the edges, and the outline is then gone over with a hot tool.

[Illustration: FIG. 33, FIG. 34.——STICKING INLAY ON MOROCCO GROUND WITH TOOL (FIG. 33) INSTEAD OF ROLLER, TO AVOID CRUSHING THE GRAIN]

[Illustration: 12. SHIELD OF CUT AND EMBOSSED LEATHER, _CUIR BOUILLI_. ITALIAN, 16TH CENTURY.]

MOSAIC IN RELIEF

The term mosaic is perhaps not very correctly applied to this style of decoration, in which the shape of the design is indented, by pressure, on the damp surface of the groundwork, and filled in with an inlay of leathers thick enough to stand out in relief, and be subsequently carved. A thin kind of cowhide[8] specially prepared for embossed work is used. The design is traced upon it in the manner described for carved leather, and a preliminary modelling is executed indicating the outlines and veinings as strongly as possible. The high reliefs may be embossed and lightly stuffed. This done, it is placed upon Bristol board, not less than half the thickness of the leather itself, with a piece of red transfer paper face downwards in between. The whole is firmly fixed upon a drawing board so that nothing can get displaced, and the design is cut out with a stencil-cutter’s knife (Fig. 22). If possible, both leather and Bristol board should be cut through at the same time, but should the knife not penetrate the latter sufficiently to cut it through, the outline will have been marked on it by the transfer paper and it may be cut out separately. The leather and the board must, however, be absolutely identical in shape and very sharply cut. With the die thus formed by the Bristol board, the morocco groundwork is depressed to receive the inlay. It is thoroughly wetted and the water allowed to sink in. The board is then placed in the exact position which the leather inlay is to occupy, and covered with a very thick sheet of blotting-paper to protect the grain of the groundwork from being crushed too much. The whole is well pressed in the copying-press until the die has sufficiently entered into the leather. The leather inlay should then be tried in the hollow thus produced, and trimmed where necessary if it be too large. After pasting it thoroughly, taking care not to omit any small points, it is placed in position on the groundwork and worked into the hollow with a modeller. The work is then placed under boards to dry; a press would flatten the relief too much.

[8] Kip-skins.

When the paste is quite dry and the leather well stuck, the carving may be proceeded with as described in