Because we want to make our hairwear with the utmost respect for our planet, we've spent a long time searching for leather that's both high-quality and as sustainably tanned and dyed as possible, without metals and using plant-based materials. The name for this is "eco-leather," although this term isn't protected and even that kind of leather requires a lot of water and energy. So it's still a bit of "greenwashing."
A friend (from the beautiful bag brand NudeBy) recommended a small tannery in Portugal, a family business run by two brothers, who uses entirely vegetable tanning methods.
After visiting this tannery, where we learned all the steps of the tanning and dyeing/coating process, as well as how to do business in Portugal (read: lunch with plenty of wine), we decided that Helder and his brother would become our regular suppliers.