I was telling you how to go about it if you wanted to go on an expedition here, (and also, sort-of, in a modern sense, here), but I may have forgotten to tell you how to make leather. Just in case I did forget, here’s the recipe.
First, slaughter your animal. I know, squeamish, are you? A lot of things you need to do when going on an expedition where there aren’t any shopping malls involve slaughtering an animal: Washing your clothes? slaughter an animal and get the gall bladder; Making soap? keep the fat from all the animals you slaughter; Need a boat? kill two buffalo bulls.
So now you must skin your animal, lay the skin flat and cover the fleshy side in salt or sand, to dry it out and delay decomposition. In a few days the hide will become hard and tough. Now soak the hide in water: this cleans off dirt and softens it up again. Scour it to remove any remaining flesh, then soak it in urine to loosen the hair, which can then be scraped off. Mix poo and water into a slurry, and soak your skin in that: enzymes in the poop will cause it to ferment, softening it and making it more flexible. You can help this process by standing in your poop slurry and kneading the skin with your feet — sorta like crushing grapes.
You now have rawhide: hard when dry, supple when wet. Useful for binding: to attach a blade to a stick and make an ax, just wrap a strip of wet rawhide securely around both and let it dry. It contracts and fits very tightly indeed.
But we were making leather, so now you need to collect the bark or wood from trees high in tannin. Look for red- or brown-colored hardwoods. To extract tannins, shred your wood or bark and boil it in water for several hours. Stretch the animal skin out and immerse it in your tannic solutions of gradually increasing concentrations for a few weeks. During this process, the stretched-out skins trade their moisture for tannins, altering the hide’s protein structure to make it more flexible, more resistant to rotting, and water resistant.
And that’s it: In just a few short weeks, you have produced leather! Now you can make yourself some shoes, harnesses, boats, water bottles, whips, and protective armor.
And they’ll last! Have a look at this leather shoe from Armenia. Made in 3500 BCE – that’s 5521 years ago!
from How to Invent Everything by Ryan North – Riverhead Books 2018