#cuircisile

Wikisource: Guide manuel du doreur sur cuir

Authored by: Émile Bosquet

https://fr.wikisource.org/wiki/Guide_manuel_du_doreur_sur_cuir/7

[Translated from French]

L’art du cuir ciselé et modelé: incised and engraved leather and their application to binding, etc.

The incised and engraved leather, whose origin is lost in the mists of time, was the precursor of a marvelous art which one indicates by the name of cuir ciselé et modelé. Its application to binding, according to the only documents which have come down to us, dates from the end of the Middle Ages. We owe it to artist monks living in a Nuremberg monastery (Nürnberg). [...] 

One cannot cover a binding with chiseled or patterned leather, without deforming chiselling and modeling and giving a presentable shape to the binding. They then serve as accessories, taking place on the cover of the bound book in the same way as an ivory, wooden or metal plate and this in ad hoc openings in the boxes of the cover. The boxes of these binders are thick, massive and heavy, often, while they are ordinary formats, out of proportion to the dimensions of the book.

Here are some ideas on how to emboss leather from a bound volume.

The strongest calfskin, hardly more than two millimeters thick, and this thickness being on the other hand, a cause of difficulties in properly carrying out the work of the blanket, the ends of the blanket are thinned down. [...] If the volume is of a large format, or if the design includes mascarons or ornaments which require fairly pronounced reliefs, these parts are drawn beforehand on the cardboard boxes of the cover and pieces of the same type are glued to these places leather, the edges of which must be trimmed and shaped accordingly; then the volume is covered, taking care to tighten the skin as little as possible, so as to retain a certain elasticity. [...] These punches or chisels are, as required, made of steel when it comes to dry chiselling; either in ivory or bronze when it comes to operating on wet leather. We also use the latter being heated, so that the crushing is more complete and thereby helps to accentuate the reliefs of the unaffected parts. These parts, more or less moistened with sweetened vinegar, which are applied by means of a hair brush, are at the same time shaped using punches or small spatulas in ivory or bronze. [...]

To help in the formation of the reliefs and especially to accentuate them, we make at their base, incisions in the skin and this by means of the tip of a very fine and pointed penknife, which the operator holds [...] while pressing the index finger on the back of the blade to bring it towards him while making the cut following the contours of the drawing. The skin is then pierced in certain places, using more or less curved punches [...] and the skin is lifted with part of the cardboard. We thus manage to form very accentuated reliefs, suitable for modeling mascarons, figurines, etc. [...]

Since calfskin, cowhide, etc. are more or less porous, they should be glued, first with starch glue and then with gelatin or dextrin, before applying the dyes. Sometimes oil colors are applied; it is then advisable, in addition to the seat indicated above, to use a layer of metal; leaf gold is much better. It is adhered to the skin by means of a layer of egg white, prepared as for gilding on leather [...] The application of egg white is done using a hair brush; leaf gold is applied immediately afterwards, pressing and dabbing with a cotton ball. It is important to allow it to dry completely before coloring. The gold layer in sheets or shells not only serves as a basis for the colors but appears as the case may be, through those applied in lighter layers as well as in places intentionally left uncovered. Byzantine art lends itself admirably to this kind of decoration.

[...] The application of cowhide to the binding is of more recent times, not that it is possible to bind any volume whatsoever with this kind of skins, which not only are too thick, but also too tough to lend itself to this kind of work. But these leathers, beaten and laminated in plates of 3 to 6 millimeters thick, are applied to book plates. [...] The binding itself, once these preparations are made, can be covered with any skin. This frames the [cowhide] leather plate, which is adjusted with the desired precision so that it becomes one with the cover.

The ornamentation of these plates is generally done before their application to the volume. 

Here is the way to operate: The drawing that one wishes to reproduce is first traced in all its details. [...] Then, using the tip of a penknife or any other sharp point. We incise at peak and at about 1 and a half millimeters deep, all the contours of the drawing, then we make a second incision following the same contours, [...] but by cutting this time at an angle, so as to join the first incision at its base, which removes twigs of leather and forms a hollow sufficient to bring out in relief the various parts of the design.

These hollow cuts are then ironed with a steel punch, the tip of which is more or less blunt, and hot enough to give these hollowed out parts a clean and well-cut shape, the operator having great care in passing the heated rod of the press as strongly as possible against the sharp cut wall.

Some practitioners do not quite work this way, they only make one vertical incision; then, using a white-hot tool, they dig, next to the incision which serves as their guide, a more or less strong net by burning the skin. This method, rather unpleasant to practice, on the other hand causes carbonaceous slag which must then be removed with care [...]

Hot chiseling can be replaced by the engraver's chisel, provided that the leather is strongly beaten or laminated. The use of the chisel requires special studies and is part of the art of the engraver. In addition, hollow steel chisels of very fine hardening and special sharpening are needed to chisel the leather with the desired clarity. [...]

AIC Wiki: BPG Book Decoration

https://www.conservation-wiki.com/wiki/BPG_Book_Decoration

Decorative Techniques

Cuir-bouilli

“A method of decorating a book utilizing the capability of a vegetable tanned leather to be molded when wet. After being thoroughly softened in water the leather can be formed or molded into various shapes, which, on drying, retain those shapes with a remarkable degree of permanence. The wet-mold leather can be more permanently set by drying it under moderate heat, the degree of rigidity obtained cuir-ciselé being determined by the drying temperature. A faster method, and one that produces extremely hard and rigid shapes, is to dip the molded leather into boiling water for anywhere from 20 to 120 seconds. This is the process that gave rise to the name "cuir-bouilli." Such a process involves the partial melting of the fixed tannin aggregates in the leather. At a temperature approaching 100C. these aggregates become plastic and can be made to flow and redistribute themselves throughout the fiber network of the leather. On cooling, the fibers become embedded in what can best be called a tough, three-dimensional, polymer network or resin. [...] The leather actually sets so hard that some books bound in this manner required no boards. The decoration itself was executed by cutting the leather lightly while damp, after which the design was hammered in relief. The shaped leather was then immersed in boiling water, and dried, and the depressions were filled with molten wax so as to preserve the designs.The molding of leather was known in Saxon times in England, and was widely practiced during the middle ages in both England and on the Continent. The motifs used were generally mythological animals and interlaced foliage.” (Roberts & Etherington, 69-70) 

Cuir-cisilé [cut-work]

“A method of decorating a bookbinding in which the design is cut into dampened leather instead of being tooled or blocked. The design is first outlined with a pointed tool and then dampened. It is then brought into relief by depressing the background, usually by stamping a succession of dots into the leather very close together by means of a pointed tool. Certain parts of the design are sometimes embossed from the flesh side of the leather, and in such cases the decorating must be done before covering.This technique of embellishment, which may well have been the highest manifestation of the medieval bookbinder's art, was widely practiced only during the 15th century and only in certain areas, principally southeastern Germany and in Spain. No English and Flemish and practically no Italian examples are known.The finest cuir-ciselé bindings have been identified as the work of Mair Jaffé. More recent (and excellent) examples were produced in France by Marius Michel, c 1866.” (Roberts & Etherington, 70)