Cuir bouilli

Cuir bouilli or cuir-bouilli (pronounced "queer boowi"), meaning boiled leather, but often left in the French in English, was a historical material for various uses common in the Middle Ages and Early Modern Period. It was leather that had been treated so that it became tough and rigid, as well as able to hold moulded decoration. It was the usual material for the robust carrying-cases that were made for important pieces of metalwork, instruments such as astrolabes, personal sets of cutlery, books, pens and the like. It was used for some armour, being both much cheaper and much lighter than plate armour, but could not withstand a direct blow from a blade, nor a gunshot.

Alternative names are "moulded leather" and "hardened leather". In the course of making the material it becomes very soft, and can be impressed into a mould, to give it the desired shape and also decoration, which most surviving examples have. Pieces such as chests and coffers also usually have a wooden inner core.

Various recipes for making cuir bouilli survive, and do not agree with each other; probably there were a range of recipes, partly reflecting different final uses. Vegetable-tanned leather is generally specified. The subject has been the subject of much recent discussion, and attempts to recreate the historical material. Many, but not all, sources agree that actual boiling of the leather was not part of the process, but immersion in water, cold or hot, was.

Cuir bouilli was used for cheap and light armour, although it was much less effective than plate armour, which was extremely expensive and too heavy to be worn by infantry. However, cuir bouilli could be reinforced against slashing blows by the addition of metal bands or strips, especially in helmets. Modern experiments on simple cuir bouilli have shown that it can reduce the depth of an arrow wound considerably, especially if coated with a mineral facing mixed with glue, as one medieval Arab author recommended.

In addition, "armour based on hide has the unique advantage that it can, in extremis, provide some nutrition", when actually boiled. Josephus records that the Jewish defenders in the Siege of Jerusalem in AD 70 were reduced to eating their shields and other leather kist, as was the Spanish expedition of Tristan de Luna in 1559.

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Wikipedia