Hardening Leather (COG)

Hardening Leather

by Lord Christopher of Grey (published to the Sacred Stone email list October 26, 2013 at 2:55 pm)

As a nearly 20 year leather worker let me step in here and make a comment or
two about courbouill, the real name for hardened leather. In the SCA it is
a common misperception that the only way to harden leather is using boiled
wax. While the process works it is messy and potentially dangerous as heated
wax can and does burn! In truth, leather hardens when raised to 120
degrees and kept at that temperature for a while, short while. The process
leather undergoes is called elastomerization. Basically it is a changing of
the structure of the leather resulting in a significantly stiffer piece of
leather. Any material that maintains the proper temperature to heat the wax
works. Wax just has a better heat retention than water. However, typically
wax hardened leather retains its waxy feel and is a somewhat messy thing.
So let me share some other ways to harden leather.

First, and most gross, is to soak your leather in urine. This is THE most
period accurate method for hardening leather. It’s the salts in the urine
that harden the leather. Of course you will be hard pressed to find anyone
who would want to fight you or even be close to you!

Water. For smaller pieces such as bazabands, gorgets, you can simply misty
them with a spray bottle. Not soaking just very damp. Put your piece in a
pre-heated oven that is turned off, for about 10 minutes. You don’t
actually bake the piece, just warm it. I typically set the oven to 200
degrees then when it’s to temperature, turn it off wait a minute or so then
put the piece in. When you take the piece out it will be very warm and
still flexible. Shape it as needed, i.e. for a bazaband, shape it to your
arm. Then let the piece cool and dry in that shape. It will now be hard.

Simply wearing the piece and sweating in it will also harden it but that
will take a long time and lots of thumps before it becomes hard enough.
Just think about that favorite pair of work boots. After 6 months to a year
they are hard right? Yeah, because you sweat in them and your body salts
along with the gentle warming, your body temperature, hardened the leather.

For larger pieces the water method still works. But now you have to have a
pot of just below boiling water big enough to submerge the piece in.
Submerge it until all the tiny bubbles from the leather stop coming up.
Remove the piece, shape and let cool as with the smaller pieces in an oven.

Just for grins and giggles to test the water method, cut a piece of leather
1 inch square. Drop it in boiling water for about 10 – 15 minutes. When
you take it out it will be flexible. Let it cool. When cool it will be
black and about 3/4 inch square, yes, it shrunk from the process. Now place
it on a hard surface and strike it with a hammer but not real hard. To your
amazement it will shatter like cheap plastic. This is what happens to ALL
leather that is over hardened. Also, if you took the time to do any
stamping or carving on the piece it will be impossible to see if at all. So
with any hardening process, be careful and do not overdue it!

Here is a link to the water hardening process
http://www.pbm.com/~lindahl/cariadoc/perfect_armor.html .

Now your choice of leather to start the process is also critical. 5 – 6
ounce leather just won’t cut it. Leather is measured by the ounce. What
that means is one ounce is equal to about 1/32 inch. Thus higher ounce
number, thicker leather. Most armor is best made out of 10 – 12 ounce
leather. All leather is sold in a range as I’m giving here as it is a
natural product and as such not consistent across an entire piece. There
are leather pieces out there referred to as armor bends. Basically they are
usually a double shoulder, yes relate to its original owner, and 12 – 14
ounce. This is heavy and fairly stiff to begin with. Now sometimes you can
find leather that has been compressed. This is often used for shoe/boot
mid-soles. They take a piece of 12 – 14 ounce leather and press it down to
10-12 ounce thickness. It results in a very stiff piece of leather.

Your next issue is what type of leather in the sense of how was it tanned.
Chrome tanned leather is tanned using chromium salts. This lather is most
commonly used for work aprons for folks who shoe horses or are blacksmiths.
It is very stiff and tough. However, the chrome tanning process creates a
leather that is somewhat water resistant. There are pros and cons to this
type of leather for armor but you will not be able to increase its stiffness
using the techniques suggested here in Achbar’s original post. You spot
chrome tanned leather by looking at a cut edge. It will be dark all the way
through. Usually it tends to have a bit of a waxy feel to it as well. The
more period accurate method of tanning is vegetable tanning. If you boil
acorns to get rid of their tangy flavor the water is brown. That is the
tannin used to vegetable tan leather. (You can also use that water to cure
dandruff and a myriad of other sicknesses.) Veg tanned leather is what is
used for stamping and tooling. It is a light beige color and accepts all
dyes for color of choice. You can also get drum dyed veg tanned leather.
You can tell it’s been drum dyed by looking at a cut edge. If the edge is
the same color as the rest of the lather, drum dyed. Not a bad thing.
Colors like blue and white are best done drum dying. The issue with veg
tanned leather is that all the hardening methods here work on it as it is
not water resistant in any manner. You can apply coatings to make it so,
but in its natural state, no.

Now the worse leather for making armor is furniture bends. In our area one
can often find these for great prices. A side of leather, furniture grade,
can run about $100 or less, depending upon total square footage. Typically
a side runs about 23 – 26 square feet. A double shoulder about 10 – 12
square feet. You can also get bellies with about 10 square feet but these
are long strips about 12 – 18 inches wide and the leather is softer at the
same ounces as regular sides and shoulders. Furniture bends are typically a
full side or often a full hide. So you are getting about 25 – 55 square
feet per hide. Problem is this leather is about 6 – 7 ounce and very
flexible. Think about it, would you want to sit on a couch that is as hard
as a cement bench? Furniture leather is great for clothing like vests or
shoes, pouches, bags, etc. All furniture bends I’ve ever seen are also drum
dyed so great color choices.

The final type of leather that actually does work for armor but only for
armor like coat of plates or the like. This is mistakeningly called suede.
It is not suede. Real suede, i.e. nubuck, is full grain leather, meaning
the smooth side is original owner’s outside, rough side the owner’s inside,
that has been drawn through brush rollers rotating backwards to the
direction the leather is being drawn. This scuffs up the surface of the
leather creating nubuck. Suede is split leather, thus is more properly
called split grain leather. When leather comes off the original bovine
owner it is about 3/4 to 1 inch thick. It gets run through a splitter after
tanning to spilt it down to the size required. Thus there is only one piece
of full grain leather per hide. All the rest is split grain. Split grain
leather stretches and is not water resistant nor can be made water
resistant. Good for shoes, clothing, bags, and the like. Now if used for a
coat of plates the garment as seen worn is made of split grain for its
flexibility. However, riveted inside are squares of 10 – 12 ounce leather,
the plates. Thus the split grain is simply a garment holding these plates
in place. Very functional, flexible for movement and very period.

Well you don’t exactly walk into the local mall and find a leather store.
The crafts stores, ACMoore and Michaels, sell very small pieces of split
grain leather for crafty things. In our area we have two great outlets
though. The first is Tandy Leather. Outlet stores in the Raleigh and
Charlotte areas. The other is Zack White’s in Ramseur. Zack’s caters to
the equine industry so they often have things Tandy does not. Both outlets
are also available via the internet. For example at Zack’s you can buy
rings from about 1/2 up to 3 inch in diameter. Make yourself the split
grain outer garment of a coat of plates but mount these rings on it. Very
period version of a coat of plates. Of course it will also be VERY HEAVY!

Anyway, there you go, enjoy. Remember to keep your leather tools very sharp
and that if they can cut leather…………..you are covered with leather,

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