Interesting to know how long that technology hung on. Manufacturing firms, at least the small and middle-sized ones, don't throw out what WORKS.
We've largely forgotten the MANY industrial uses of leather, not to mention that it was one of the main, indispensable, components of our transportation system back when that was literally horsepowered. And for centuries it was a vital part of the military, not just for transportation and "fighting vehicles," but body armor.
When I lived in the former industrial birthplace of America (Hudson River and Mohawk river valleys) I saw many remnants of the factories that had been powered by water-driven leather belting, and of the remains of the tanneries that provided that material. A different world, and smellier, I'm sure. One of the upsides is that you can now fish in most of the streams that were the "waste disposal systems" for those tanneries. For many decades before my time, there was no life in them above the bacterial level....
On the other hand, leather itself, unlike most of its replacements, is biodegradable. Requires a lot of nasty processing and labor, but no petrochemicals.
