Tanning is the process in which animal hides are turned into leather. There are two ways to convert hides into leather: chrome tanned leather, which involve the use of different chemicals and minerals; and vegetable tanned leather in which there are substances used called tannins, natural extracts derived exclusively from vegetable sources.
The vegetable tanning process is more artisanal than the chrome tanning, making a better product, not only for the eco-friendly reasons, but also the higher quality. The use of natural tannins have no negative impact in the environment. It doesn't produce any toxic wastewater as the chrome tanned leather does.
Vegetable tanned leather is not the same as "vegan leather". Leather must refer only to materials processed from animal skin. The so wrongly called "vegan leather" is nothing but a plastic material created to look similar to leather, which end up having a bigger carbon footprint than vegetable tanned leather.
Not a single animal is sacrificed in order to just extract the skin, the tanneries use the waste of the food industry in order to produce leather. So, with this being informed we can conclude that the main material used in our sandals is on the level of our workmanship and product quality.