Cuir Bouille

Water hardened leather mask

Water hardened leather mask

This week’s article sets out to describe the research and development of the historical technique of forming leather through the application of water and heat, often referred to as Cuir Bouille. I was inspired to undertake this research due to mention in the Tournament Book of King Rene of Anjou (1460), of a helm being worn formed entirely of leather to participate in the tournaments of the day in Brabant, Flanders and Hanault.

“ Et quant à leurs armeures de teste, ont ung grant bacinet à camail sans visière, lequel ils atachent par le camail dessus la brigandine tout autour, à la poictrine, et sur les espaules à fortes agueilletes; et pardessus tout cela mettent ung grant heaulme fait d’une venue, lequel heaulme est voulentiers de cuir boully et pertuisé dessus, à la largeur d’ung tranchoires de bois, et la veue en est barrée de fer de trois dois en troys dois, lequel est seulement atachié devant à une chaesne qui tient à la poictrine de la brigandine, en façon que on le peult gester sur l’arczon de la selle pour soy refréchir, et le reprandre quant on veult. “

English Translation:

“And over all this they put a great helm made all in one piece of cuir bouilli and perforated below, the size of a wooden trencher, and the eyeslot is barred with iron in a grid three fingers square, which is attached in front by a chain to the breast of the brigandine, so that you may hang it from the saddle to refresh youself, and put it on again when you wish.”

I struggled to believe that leather could be suitably hardened to such an extent as to be acceptable for head protection and began to undertake research into the technique of Cuir Bouille in an attempt to better understand the methods used and the subsequent qualities of hardened leather.

With further research it became clear that this technique was not only used for armour but saw much use in the making of objects such as the 15th century leather case held by the Cluny Museum or the masks of Venice from the 12th to 18th century.  This research revealed more mysteries than it solved but testing did allow me to gain skill with the decorative forming technique of leather and an understanding of why Froissart in his chronicles of the early 15th Century described these techniques as providing armour made of “leather that no iron can pierce”.

Historiography and Methodology

Although Cuir Bouille is well referenced in period sources to date no historical source from before the 18th century, describing the specific technique of its creation has been discovered. It appears to have gone out of fashion in the late 19th Century and was then replaced by other techniques at the turn of the 20th Century. For many decades the argument was put forward that true Cuir Bouille involved the saturating of leather with bee or paraffin wax. This has not been verified by any historical item from the middle ages and is now largely considered to be a modern (post 18th century) technique for hardening leather. Much of the modern research has been undertaken by amateur historians, recreationist craftsmen and guilds such as the cobblers and shoemakers guild. Marc Carlson has been the most prolific recent primary researcher into the subject of Cuir Bouille and has managed to document many of the historical mentions of the technique in armour production:

“1375 Barbour Bruce xii. 22 On his basnet hye he bar Ane hat off qwyrbolle.
1386 Chaucer Sir Thopas 164 Hise Iambeux were of quyrboilly [v.r. quereboly].
1400 Mandeville (Roxb.) xxvi. 123 ai hafe platez made of coerbuille.
1413 Lydg. Pilgr. Sowle iv. xxx. (1483) 80 A feyned hede formed of playstred clothe other of coerboyle.
1513 Douglas ?neis v. vii. 77 Thair harnes thaim semyt for to be Of curbule corvyne sevin gret oxin hydis.”

Other recent research has been carried out by Jean Turner and focuses on the more decorative and civilian uses of the techniques. I relied on papers by both these individuals to assist in documenting and verifying techniques and processes.

The method undertaken for researching the technique was to begin with gaining an understanding of items created with the technique and looking for evidence of the technique applied. During the initial stages I also looked into historical mentions of the term Cuir Bouille (in all its spellings) to determine any notable traits that would help to identify the technique. For the physical experimentation leathers were selected to be as close to the historical leathers as possible using vegetable tanning processes and all attempts were made to use tools that would have feasibly been available to the historical craftsman in Europe during the period. This was not as difficult a task as it could have been as leather work uses few power tools or tools that would have been unavailable. After the initial research into the techniques was undertaken looking at the effectiveness of different techniques for armour production a study and development of skill was undertaken into the techniques for civilian use and the creation of leather sculpture for the purpose of masks or children’s toys.


At the time of King Rene we know that in London there was not a guild specific to all leatherworkers but rather a series of guilds each focusing on a different aspect of leatherwork.

  • Armourers (armour-makers)
  • Cordwainers (workers in fine leather)
  • Curriers (dressers of tanned leather)
  • Girdlers (girdles and belts)
  • Loriners (stirrups and other harness for horses)
  • Saddlers
  • Skinners
  • Tanners
  • Upholders (upholsterers)

Each of these guilds would have made use of leather in their profession and the curriers, saddlers and armourers would have made use of water hardened leather. Rather disappointingly none of the modern guilds were able to provide information on the historical technique used by their guild fellows for the purpose of hardening the leather. One guild member within the curriers guild suggested that his guild had held very close ties with the Tallow Chandlers (animal fat candle makers) this information was helpful in gaining an understanding of the change to wax hardening methods being associated with Cuir Bouille which will be discussed later.

The use of leather for protection has been traced to Egypt but is believed to be an earlier behaviour. By King Rene’s time leather armour would have reached its pinnacle and at the conclusion of my work it was determined this armour was as good, if not better than steel for the needs of the medieval knight in the tournament. Although simple pieces could be produced at a far lower cost than equivalent steel armours according to tournament receipts the more intricate pieces were not significantly cheaper than their steel counterparts. The leather armour described by Rene would have been owned by knights of a mid-level economic standing.  King Rene also addresses the use by all participants of Cuir Bouille for the “ lambequin des armes” (armorial mantling) which would be a cuir bouille figure attached to the top of the helm displaying the knights crest and colours.

Cuir Bouille was not only used by knights as can be seen by its extensive use for masks in Venice and its use in extant boxes and containers used by all classes in England and the northern territories. Although it does not survive well in the archaeological record it is reasonable to believe that hardened leather formed a regular part of life for someone of the early modern and medieval past.


I sought to identify the most likely technique applied to create both civilian and military pieces. This research was a continuation of that carried out by Marc Carlson, David Friedman and Rick Cavasin to include the use of animal gelatine in the process. During the experiments it was possible to gain the same results as the previous research within safe parameters and so it seemed fair to advance the research making use of the information gained from the curriers guild.

My hypothesis was that the use of tallow provided by the tallow chandlers would have led over time to the mistaken belief that bees wax was used in the hardening of leather, as tallow chandlers primary role was the production of cheap (non-beeswax) candles. When the experiments were carried out on various thicknesses of leather impregnated with animal gelatine (substituted for tallow) the results were an increase in strength and decrease of brittleness in the cuir bouilled leather. These pieces did not suffer the problems recognised in those impregnated with paraffin or beeswax as later application of heat caused no ill effect and they became extremely difficult to pierce[1]. This technique also made the cuir bouille impervious to water without a finish and made the leather significantly softer in the forming process allowing more intricate work to be completed. It is unlikely this was a method employed for daily civilian items (other than shoes) due to the water hardening method being suitable for most items but it is likely to have been the preferred method of armour creation. An american revolutionary war soldier provides evidence that a method of impregnating leather with tallow existed in 1776:

“We would go to a turner or wheelwright, and get head blocks turned, of various sizes, according to the heads that had to wear them, in shape resembling a sugar loaf; we would then get some strong upper, or light sole leather, cut it out in shape, close it on the block, then grease it well with tallow, and set it before a warm fire, still on the block, and keep turning it round before the fire, still rubbing on the tallow, until it became almost as hard as a sheet of iron… We made the scabbards of our swords of leather, by closing on a pattern of wood, and treating it similar to the cap.” — Recollections of a Revolutionary War Soldier [reprint 1854 edition]”

This may be after the period being studied but shows that this method of hardening leather was known and was effective in creating pieces of armour.

Below the water hardening technique will be described followed by the animal gelatine technique. Both techniques require the use of unfinished vegetable tanned leather.

Water Hardening

Step 1 – Cut out the desired design of the item

Step 2 – Perform any tooling required and prepare the items so that upon hardening no further work except dying or sealing is required.

Step 3 – Soak the item until bubbles stop forming in water that is slightly hotter than is comfortable to place your hand.

Step 4 – Remove the leather and either fasten to a last (model of desired item) or begin to form the shape using ones hands (this is the preferred method chosen by I) If using a last use a smooth piece of wood to  push leather into position around the last and to ensure a good fit.

Step 5 – While forming the leather apply heat to areas so as to harden them. This can be done using a hair dryer, historically working close to a fire or other heat source would have had the same effect.

Step 6 – If not using a modern heating device it is advisable to bake the leather carefully until completely dry. Temperature should be maintained at or below 180 degrees Fahrenheit. If using a last this is the preferred method for ensuring the piece is completely dry.

Step 7 – Complete the piece by painting or dyeing and then sealing with an acrylic seal.

Animal Gelatine hardening

Historically the gelatine part of this would have been made by boiling pig or horse trotters. Due to the difficulty in acquiring such items animal gelatine was substituted instead.

Step 1 – Cut out the desired design of the item

Step 2 – Perform any tooling required and prepare the items so that upon hardening no further work except dying or sealing is required.

Step 3 – Break up gelatine sheets and insert into jam jar covered with cold water.

Step 4 – After the gelatine begins to swell (roughly 2 hours) the sheets are heated gently, while stirring, to a temperature between 22-30 degrees centigrade.

Step 5 – Once the gelatine forms a clear homogenous liquid insert the leather and continue heating to a temperature of 32 degrees centigrade. The leather will bubble and a boiling sound will be heard. Once bubbles stop appearing on the surface of the leather it is ready to be removed for forming.

Step 6 – The piece should be attached to a last or formed at this stage. The application of heat helped speed up the drying process but does not appear to be necessary for the piece to hold its form when dry.

Step 7 – Complete the piece by painting or dyeing and then sealing with an acrylic seal.

With both methods very few historical substitutions are required and it is quite possible for a modern person to recreate in full a historical item solely using historical methods. Vegetable tanning of leathers has remained relatively consistent and although there are slight differences within modern leather these are not enough to negate the project. The preparation of the water / impregnating substance could be done over a wood stove or even an open flame, for this project a gas ring hob was used. The tools used have not changed dramatically so these could remain the same although wood is preferable to metal during the forming process. As stated previously gelatine has been substituted for tallow but if tallow is locally available it should be used instead of the gelatine. The method of giving direct heat when hand forming was a hair dryer, historically an open flame would have been used but this was deemed an unnecessary risk for the research.

For a wide display of my ability with this technique please view the items at All of the dragons and masks are made solely from the Cuir Bouille technique. I am able to make armour and other hardened leather items as well but currently do not have any listed.

I hope you have enjoyed this week’s article looking at this fantastic technique. I like to view it as the equivalent of plastic for our ancestors.

Water hardened leather dragons

Water hardened leather dragons


Anjou, R.,            Le traictié de la forme et devis d’ung tournoy, MS E.1939.65.1144

Anjou, R.,            Le traictié de la forme et devis d’ung tournoy, MS français 2695

Avril, F.,                Le Livre des Tournois du Roi René, Paris: Editions Herscher, 1986.

Carlson, M.         Leatherworking in the Middle Ages – “Cuir Bouilli/Hardened Leather”     (1996-2006)

Froissart, J.          The Chronicles of Froissart, translated by Lord Berners, edited by G. C. Macaulay. Vol. XXXV, Part 1. The Harvard Classics. New York: P.F. Collier & Son, 1909–14;, 2001.

Maxwell, S.         “The Development of Leather” (2007)

Mould, Carlisle, Cameron             “Leather and Leatherworking in Anglo-scandinavian and medieval York.”              (2003)

Scott, M.,            The History of Dress Series (Atlantic Highlands, NJ: Humanities Press, Inc., 1980), 80; Jacqueline Herald, , History of Dress Series (Atlantic Highlands, NJ: Humanities Press, Inc., 1981), 53 and 216; Ruth M. Anderson,  (New York: Hispanic Society of America, 1979), 53–63; and Françcois Boucher, (New York: Harry N. Abrams, Inc., n.d.), 196.

Tieuli, M.J.          “A Short History  of Venetian Carnival Masks”     (2006)

Turner, J.             “Cuir Bouille Technique”               (2009)

[1] Considering the above referenced quote from Froissart this suggests wax hardening was not used for armour. This also replicates the research of Jean Turner.

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One comment

  • Hi! first of let me thank you for this guide and all the info it contains.

    While I appreciate the reasoning behind this study and followed your advice in making some interesting gelatine based pieces including a nice set of spaulders. However, my training in anatomy and physiology casued me to realize you are in error in using gelatine. It is no substitute for Tallow ( i will explain in a moment )

    After realizing this I experimented with real tallow which is easy to come by or make with the help of a local butcher, I found that it is a superior method in every way to the Gelatine.

    Things you must know and why the use of gelatine is wrong.

    Gelatine is almost pure protiens. Protiens are water soluble ( easily absorb water, which is why it softens when you soak it ) and become hard and brittle when dehydrated.

    Tallow is a fat. It is not water soluble and of course doesnt mix with water. It is a solid at room temp

    The gelatine hardened leather is not water proof and cracks under stress.

    Tallow hardened leather ( I boiled it in tallow at 170-185 deg F for a few mins ) does not shrink, is extremely water proof, does not crack unless bent to its max and has a springlike quality that snaps it back to shape. It hardens and stiffens well and seems to have all the right attributes for making leather.

    I appreciate this post and would love to see you try this for yourself, factcheck and perhaps re make this post with this knowledge in hand.

    Thanks again