How to Make Cuir Boilli
by sir squeak! the mighty
This article is a result of great experimentation (and several trashed kitchens). Most of the reference materials used were from newsgroups and web pages over the Internet and word of mouth, which consist more of trial and error information than precise methodology. These methods are what have worked with for me, you may wish to modify these procedures to compensate for equipment or weather. The idea of waxed leather can lead to many useful Amtgard items; historically, its most common application was for leather bottles during the Elizabethan era. Historical evidence as to the use of Cuir Bouilli in armor and shield making is minimal, but it is also probable that most remnants of its use have decomposed. Either method of waxing the leather produces sturdy results (better obviously with thicker leather) for mugs, armor, bottles, etc.
There are several things to remember when following these steps. Near the final steps you will be juggling hot wax and hot leather, so lay out your tools ahead of time to help keep the timing right and not get bogged down looking for something. Always be careful with the hot wax. I cannot stress this enough. It is very easy to burn yourself very badly with the wax (and its hard to clean the wax off your skin when it's burned). Also keep a close eye on the wax and the fire extinguisher handy. Burning wax is the original Napalm and it will take a fire extinguisher to put it out if it combusts. Finally, several layers of newspapers in key areas around the kitchen can save a lot of heartache when it comes time to clean. Wax doesn't really clean well, so prevention is the key. I have a cardboard box at home with all my wax equipment. I don't even bother to clean the spoon I use to stir the wax, I just keep it and reuse it next time.
heavy weight leather
wax (canning wax will do, you can vary types of wax for variable results)
a double boiler (a chocolate melter works)
awl and thread
stirring spoon for the wax
Preparing the Leather:
Before you start, you will need to decide what exactly you want to make. Once you have a design, you can begin to make a road map of what you are going to do. For this example, we are going to make a flask, but you can substitute your own project in these steps.
First thing we will do is to draw the shape of the flask, ovals and hexagons work well. Once you have your pattern, you will need to transfer it to the leather, using tracing paper or whatever means convenient. Next you will need to cut out each side of the flask from the leather. Mark evenly along the edges where you want to sew the sides together and punch the holes with your leather punch. Place the two pieces together, rough sides on the inside and smooth sides on the outside. Use the awl to sew the sides together very tightly, and tie off the ends at the mouth of the flask.
After we have sewn our flask, we will begin shaping it. Place the leather in a container under water until bubbles quit emerging from the leather. At this point the leather will feel like slimy clay. Dry off the leather and, using the funnel, fill the flask with sand until the sides bulge to a good size. A stick is a good tool to pack in the sand and stretch the sides. The leather will be very malleable at this point and you may shape it however you want. Once the leather is shaped how you want it, lay it in a warm dry place to dry. Drying may take 2 or 3 days, depending on the weather and the leather.
Once the piece is completely dry, preheat the oven to between 175 and 200 degrees. You probably will want to start at 175 degrees and turn it up gradually. Place the leather in the oven and cook it until the surface is completely dry. Be very careful not to burn the leather, but we want it as hot and dry as we can get it before the surface begins to crack. Once this is done we can begin the boiling processes.
Preparing the wax:
Keep the fire extinguisher handy during this part and be very careful to avoid scalding and burning from hot wax. Take your double boiler, pour some water in the bottom pan, and place the top pan over the bottom one. Set the heat for the double boiler at about Medium to begin with. Put the wax in the double boiler to melt; you may want to cut it into smaller pieces or grate it with a cheese grater to get it to melt faster. Once the wax is liquid, turn the heat down a little; if the wax actually begins to boil the heat is too high. Be very careful with the wax, because if it gets too hot (esp. if it boils) it may combust.
This method is not true cuir bouilli, but more the waxed leather approach. Take the flask from the oven and lay it out on several layers of newspapers (I like to line a box with newspapers and put it inside.) With a basting brush, baste wax onto the hot leather. Keep basting the surface until it cannot absorb any more wax; when the leather is saturated it will get a waxy film on the surface. Once you have started the basting, its is not advisable to reheat the piece so you will need to work fast. As the leather cools, it will be less and less pliable, but any last minute adjustments can be made before it sets. Be very careful handling the hot leather, it's very easy to burn yourself with it.
When the wax sets, the result will be a hard piece of leather in the shape it has been molded. This leather remains hard through most normal usage. Extreme heat (ex. cars in the summer) softens the leather and leaves it with an oily feel, but you will only need to reshape the leather and let it cool off and it will reset.
This method is much closer, historically, to actual cuir bouilli leather. Your leather piece will need to fit inside the double boiler that you melt the wax in, so you may want to invest in a larger double boiler. Be positive that the leather is shaped exactly as you want it, because with this method there is no opportunity for adjustments. Once you pull the leather piece out of the oven, place it directly into the wax, making sure that the entire piece is submerged. Tiny air bubbles will escape from the rough sides of the leather for a while, leave the piece in until there are almost no air bubbles left. The leather will actually polymerize and shrink a little. Pull the piece out of the wax with some metal tongs and lay it onto several layers of newspaper; be very careful of dripping hot wax. Once the piece is cooled it will retain its shape, even when heated. It will have a harder, more plastic feeling surface.
The finished product will be sturdy with an oily sheen. You can use old rags (disposable) to wipe away any wax resedue. If you wish to create something more artistic the leather can be tooled and dyed before the waxing. The tooling will maintain its pattern, but the natural leather color and dyes will darken, so you may want to make some test pieces before each project. The key to a good finished product is test smaller pieces until you get exactly what you want and to maintain good timing.