Bottle case in 'cuir bouilli', stamped and embossed leather, decorated with coat of arms and inscribed with date and initials. Italian, ca. 1562.

Bottle case in 'cuir bouilli', stamped and embossed leather, covering a glass 'pilgrim's bottle'. The leather is decorated with foliage and a coat of arms supported by amorini. On one side is inscribed 'IA. 10.. ALEX', and the other side is dated 1562. The top is hinged and mounted with iron.

Given by Mrs Ellen Hearn

Given by Mrs Ellen Hearn, Villa St Louis, Menton, France (RF 23/1055
Transferred to Circulation Dept. 2/1/1926 (RF 26/172)

Notes on the manufacture of medieval leather containers:

Waterer (and following him, Cherry) summarise the medieval techniques for making leather containers for dry-goods:

Stitching is the most common technique, with holes made in leather by awls. Thread is made from flax or hemp yarn rolled with beeswax. The other principal assembly technique is sticking to a wooden structure. The traditional adhesive for box covering is hot animal glue, which was often created as a by-product of the fleshings taken by the tanner from the skins or hides.

Leather objects can also be created by moulding. The traditional medieval term was cuir bouilli, though Waterer suggests that boiling could not have been used. The technique is quite simple, and consists of soaking the (vegetable-tanned) leather in cold water until it is thoroughly saturated. The leather is then very plastic and can be modelled over formers in moulds of plaster, wood or metal. If the surface is to be ornamented by tooling, stamping or punching, this must be done while the leather is damp.The leather is then dried gradually (to avoid brittleness) , supported by its mould or filling which can be removed later.

The most common processes of decorating smooth-surfaced leather are:

Incising with blunt or sharp tools
Punching to give a texture to the background of incised designs, using a variety of small iron or bronze punches (also used in book binding).
Modelling, to leave important features in low relief
Embossing, performed with a ball tool from the flesh side of leather that has been previously dampened.
Carving, which is done from the grain side with a special knife that can be inserted more orless horizontally and partially raises up a thin layer until the form appears to lie on the surface

Finally the object is decorated with coloured dyes, usually with some paint (tempera). Red seems a common colour (little work on medieval dyes). Some leather was gilded using glaire (white of an egg) or gold size to attach gold leaf which adhered under the heat and pressure of book-binding tools.

However, Davies argues that the multiple techniques of cuir bouilli have never actually been very clearly established. Cuir bouilli differs from other supported leathers in that after treatment it is rigid (without a support) and water resistant, indicating that the structure of the leather has been altered through a chemical reaction. Otherwise leather would remain flexible unless coated with a stiffening medium or mounted on a backing material. She suggests that all true cuir bouilli was made by taking vegetable-tanned leather and saturating it with water, then heating it to a temperature just before it starts to shrink, removing it from the hot water and moulding it immediately, and if necessary stitching it while wet. In this way the molecular bonding of the leather is weakened but not fully released allowing limited realignment of its molecular structure to take place in a more controlled manner. Alternatively, if the heat source application is limited to only the surface of the wet leather then it is possible that the shrinkage solely occurs in the outer layer of the leather, producing a surface hardening effect and reinforcing the structure. She speculates that by impregnating oils, resins and waxes, it may be possible to mould the structure of the leather when hot, and to produce more detailed surface decoration because otherwise this decoration would be distorted by shrinkage after tooling.


Bibliography
-English medieval Industries (ed John Blair and Nigel Ramsay, London) 'Leather' chapter 12 by John Cherry, pp. 295-318
-Conservation of Leather and related materials (ed. Marion Kite and Roy Thomson, 2006), 'Cuir Bouilli' chapter 10 by Laura Davies, pp. 94-102
-Oxford Companion to the Decorative Arts, ed. Harold Osborne (Oxford, rev.ed. 1985) 'Leathercraft' entry by John W. Waterer

W.46-1923