From the late 12th through to early 14th century we have references for pieces of armour made from cuir bouilli (hardened leather). I haven't looked through each of these references, but AFAIK most if not all of this hardened leather armour was worn over mail.

Apart from hardened leather, other options for supplemental armour include; wearing a second layer of mail, gambesons, scale armour, early forms of breastplate, and coat of plates. My question is, why would someone choose hardened leather armour to supplement their mail instead of these alternatives?

I would think that the iron armours (mail, scale, and plate) would easily be superior to hardened leather. Also modern testing suggests that armour made from layered linen is superior to hardened leather of similar weight. So what am I missing. Why did people wear hardened leather armour over their mail?

They used it because it worked. ;-)

It may been cheaper or easier to come by than worked iron plates. It might have had decorative properties that met social and aesthetic demands better than costly worked iron.

The most important concept to understand is we currently do not know *exactly* what processes were used in creating historical "cuir boilli." After thirty years investigating and experimenting, I can say with great certainty "cuir boilli" was not vegetable tanned leather soaked in hot wax of any sort. This anachronism has held back leather armour research for decades.

The current leading concepts (IMHO) are some combination of partially vegetable tanned leather and some hot liquid adhesive sizing. The possibilities are numerous.

Thanks for the reply Kel.

As for the cost. Most of the time when you come across a reference to armour made from cuir bouilli, it is being worn by a Nobleman, who could easily afford the best armour available.

Aesthetics might have played some part in its popularity, as leather could easily be painted or otherwise decorated. On the other hand a cuirie (leather cuirass) would have been covered by a surcoat, so any decoration wouldn't be visible.

Impact resistance. If it was anything like Japanese laquered leather, it would behave like a high impact plastic, and be nearly as good at preventing blunt trauma as tempered steel, though not, of course, as good when it came to projectiles and polearm cutting weapons. It is interesting that the first add-ons to the limbs are simple knee cops, a very wise bit of kit for participating in early tournaments, a perfect set-up for busted knee caps. Modern polo players use something very similar. http://www.pologearusa.com/browse.cfm/polo-knee-guards/2,222.html

James, I'll ask you, since you probably already know---Where's a good place to start looking for photos of historical pieces of leather armor? I'm fairly sure that surviving pieces are far and few between. Thanks...McM

Interesting James. So assuming that early plate defenses were made from iron, and not tempered steel, how do you think hardened leather would compare?

Helpful as always Mart, thank you. I know that cuir bouilli was a popular form of tournament armour, but I'm not sure if it was predominantly so. Would you say that is the case?

I knew that someone would bring up the issue of weight. Is leather thick enough to be used as armour actually lighter than iron? According to Chris Dobson, to make cuir bouilli you need 13 - 15 oz leather (preferably half tanned if I remember correctly). If you made a piece of armour from this thickness of leather, how would it compare in weight to an equivalent armour made from iron?

Thanks for the reply Ben.

HI,

I have done some work with cur bouilli, but not enough to give formulas and full methodology I am afraid.

What we know is that it is called 'boiled leather'. What we also know is that if you boil leather it does go hard, but it also deforms massively and unpredictably depending on how long, how thick, how dense and what part of the beast the skin comes from. So a piece from the side may shrink 20% in one direction and 30% in the other for instance. It also cannot be tooled or formed after production because it has set rock solid and it also is quite brittle.

So to restate the sentence above, what we know is that it is called boiled leather and that it is not boiled leather.

I have no idea where the boiling in wax thing comes from but have heard it for years and it does give some increase in density so this may be useful, but I can't see what improvement in penetration resistance etc it may offer.

So my theory is this.

Artist/noble/middle class, sees workers over large vats of steaming watery stuff with leather skins in them and assumes they are boiling the leather, but the workers being as socially low as pigs, never get asked actually what they are doing and so the process looks like boiling leather and that is what it gets called to confuse later generations.

I was doing a TV job years ago and got asked for a large structure of boiled leather and I of course said 'yes no problem', next problem was to work out what it was and actually it hit me in a flash and since, I have learned that other people are pushing in this direction too, but I am certain that I/we are right.

Leather starts to deform and shrink above about 70C (when wet), so make up a mixture of animal glue and heat to 65C (and this is where I never found the time to work out if thicker or runnier glue works best). Heat the skins for a couple of hours at least in the mixture, until they are utterly soaked through and every fraction of the thickness is impregnated, leave to cool a little - now remove.

Leather workers out there will now know that after two hours of hot soaking the skin will be as flexible and malleable as it is possible to be and can now be pulled over formers and pushed into formers etc, nailed down and left to dry. The material is really pretty much too hot to handle so leave it in the solution to cool down a bit first, this makes life easier on the hands.

What is notably different is that you have now added a different property to the leather; as it cools the glue hardens and so the leather becomes much stiffer, even though it may be in normal terms, soaking wet.

However the application of local heat will soften it again and this allows reshaping and tooling to be done and I am pretty sure this process is what allowed the extraordinary decoration on Renaissance scabbards like Cinquedea scabbards. Once you are happy with everything, leave it to dry for many days and - voila!. You can wet shape it when you can raise and depress the most, but it it was just water the leather would move back, but because of the heat aspect, as soon as it cools it sets into position.

I found that 4mm leather may end up between 6 and 10mm thick and everything from just slightly flexible to crystal brittle. Much experimentation required.

When I was doing the large pieces over the framework, I was hot cutting the leather with a sharp knife and a couple of weeks later I picked up a piece with a 45 Degree chamfer at the edge and set about a piece of (cheap) spruce and the leather was repeatedly cutting chunks off the side of the wood. Tough.

I also shot it at point blank with a field pile off a 250lbs cross bow, 50lbs long bow equivalent and it bounced off, but an armour piercer may perform better. It is very slash/cut resistant, but not great against penetrators like spears.

Different mixture densities, times, temperatures etc will make the material behave differently, so the belly skin soaks up more glue that the back skin.

One reason I am convinced I am right is that in fact this material behaves almost exactly like fibreglass/GRP. The leather is made of long collagen fibres, but these can move in regular leather, but fill the voids with a stiff adhesive (animal glue is brittle) and the fibres can no longer move; this gives the ability to mould a sheet of wet leather, the tensile strength of leather and the stiffness of glue. For those out there who know GRP, this is exactly the way it works.

I am pretty sure this is how the Roman anatomical armour was made.

I have never messed about with it much, but once you do, it is very clear what a fantastic material you have just created and I would love to have the time to get better.

This is just my experience and thoughts.

Tod

And as others have said, different kinds of armour are good for different things. If you want to have a vigorous fight with clubs (a tournament or melee on horseback) then hardened leather is great, because it takes a pounding and springs back into shape.

I believe there are two reasons why leather was so "popular" compared to steel plates in the 13th and 14th century.
First of all you had to develop the armouring techniques first. You can't just make a bascinet without anyone ever inventing it. So some parts of the body simply got filled with leather as no steel equivalent was around. Later on once the steel version was available we have to deal with the price. Looking at early coat of plates we see that most of them have rather small plates. Making big sheets of steel is something that needs to be invented first. Now of course you can always take a hammer and stretch the material around to create a halfway decent sheet of steel. But for a production on an industrial scale this is not sufficient. I'm looking into this topic right now (the steel making) and what can clearly be seen is that at the beginning of the 14th century there were *some* hammers around but by far not as many as in later days. For example in 1326, 34 workshops (smelter + hammer in this case) existed in Upper Palatine, in 1390 we have 97. In 1326 surely not every workshop used water as a power source. This development starts in the 14th century, in some areas (for example Spain) not until the 16th century. The crafts specialized while at the beginning the hammers were at the same place like the bloomerys in the course of 15th century these are being separated. Leading to a higher productivity. More steel, more steel available means cheaper steel.

I've read, both here and elsewhere, that the meaning of the word boil has changed over the years, and it didn't always mean heating a liquid until it evaporates. One theory is that boiling meant the removal of water, but not necessarily through evaporation. Water could also be removed through slowly drying out the leather. Another theory is that boiling used to mean something closer to cooking or baking. As has already been said, the term boiled leather can be misleading.

One reason why period accounts of cuir bouilli usually referred to the armour of the Nobility is because accounts tend to focus more on these individuals and less on the common soldier.

Jason

Thanks for the replies everyone.

The cuirie seems to have first been used in the late 12th century, right around the same time that we see the the first iron plates defence for the torso (Richard the Lionheart). Apart from plate armour, which was only just beginning to be worn by the highest levels of society, there was also the option of wearing a second layer of iron armour in the form of mail or scale. So most Noblemen could certainly afford, and probably had access, to two layers of iron armour for his torso If he so chose. Even if, for some reason, a second layer of iron armour wasn't available, there was always the option of wearing a gambeson outside one's hauberk. This is why I think wearing cuir bouilli (for the Nobility at least) was a deliberate decision, and not much effected by cost or availability.

So we know that cuir bouilli was a popular choice for Noblemen fighting in tournaments. Do we know if it was also popular for Noblemen in battle?