I've read a few things about vegetable-based leather alternatives; not vegetable tanning, but the leather itself being made from such things as palm fiber and fruit skins. This is something I'd love to try. Not that I'm morally opposed to animal leather, I just find that plant materials are a lot easier to obtain in my current situation. But I can't seem to find much information on how to tan veggie hides, searching "fruit leather" only gives me snack recipes, and I doubt traditional leather-making processes would work with cellulose instead of collagen. Anyone know more about this?
“Piñatex is a byproduct of the food industry,” explained Hijosa. “Once the pineapples are harvested the plants are left to rot.” Instead of letting that happen, pineapple farmers gather the leaves, extract the fibres and degum them in closed tanks. Once they have been degummed, the fibres become soft and breathable and can be put through a mechanical process that turns them into a non-woven mesh material that ends up feeling much like felt.
It looks like the pineapple leaves are treated with a process something like flax or sizal to extract the bast fibers.
For flax, the plants are retted (controlled rot) to remove some of the 'glue' that holds the fibres to the rest of the leaf. Once dry, it becomes relatively easy to separate the fibre from the stem. At this stage, if processing by hand, we have a long fibre that is excellent for spinning and shorter fibre which makes an inferior yarn. This short fibre is called tow and can also be used to make a kind of paper. Lay the tow in layers, with the fibres facing different directions (first layer horizontal, second verticle, and so on) until it is 5 or 6 layers thick. Place them between two window screens, and thoroughly wet the fibre. Use a rolling pin to apply pressure, rolling back and forth, and the natural pectins and other elements in the fibre will glue the tow together to create a kind of paper.
Going from the description above, it looks like a variation on this method, only perhaps with some other binding agent? It looks like it is dried on a textured surface to create the leathery look. I don't know how it is made waterproof, that's why I'm guessing another binding agent.