Water Hardening Leather- Cuir Bouilli

by Willow Enright

Tyrell Armor all dry after Water Hardening.

The process of water hardening leather is a time old tale which the French commonly came to refer to as Cuir Bouilli, or boiled leather. It’s not a particularly difficult process, but it does require some knowledgeable finesse. I’ve narrowed it down to five steps. Mostly, you need some water, leather, a large enough pot to soak the item you are working with, something to protect your hands, and nowadays a thermometer is recommended for consistency. 

This is the Tyrell Armor after being Cuir Bouillied and is being held and shaped into place.

How to Water Harden Leather

1. Take a piece of vegetable tanned leather, and submerge it in regular room temperature tap water long enough to get it good and soaked; about ten minutes does the job.
   
2. Heat a pot of water large enough to fit your leather item to 180° using a thermometer to gage the temperature, then you immerse the leather in the hot water.
   
3. Do this for approximately 60-120 seconds depending on how hard and thick you want the leather to become. Watch it carefully to ensure that it doesn’t burn. Whether you’re a first timer or a veteran, watching is the most important part of the process. The leather will darken as it starts to burn, and the edges will start to curl. Obviously, the longer you leave it in the hot water, the harder, thicker, and darker it becomes. You should always experiment with scrap pieces before using your main project leather.
   
4. Using protective gloves remove your steaming hot leather item and form it to whatever you are creating. The leather remains hot for a few minutes and is quite elastic for 1-3 minutes before cooling down into its hardened shape. So work fast to get it into place.
   
5. Be sure to check on it routinely to continue to mold and shape it and ensure that whatever you are securing it with doesn’t leave marks or stains behind that you can’t live with. Once it dries there’s no going back. Unless you repeat the process, but then it will be so hard and thick that you might hate it even more. ​
   

This is the Tyrell Armor with a little burnt edge. BE CAREFUL! This was amazingly difficult to shape and cut.

So whether you call it boiled leather, Cuir Bouilli, or water hardening we are all talking about the same thing. There’s also the use of wax to harden, but I haven’t yet experimented with this way, if you have I would love to hear about it. There is also, the basic wet forming which I covered in a previous blog. Click the words Wet Forming for the link. For further questions you can leave a comment or send me a message on Facebook.