Regardless of the type of tannin, the starting point is always plant-based: wood, cortex, fruits, rind, lump, or leaf depending on the characteristic of the species. The tanning agents are extracted through simple methods, such as hot water extraction or grinding.

Tannins are pure natural products derived from renewable sources, such as leaves, fruits, wood and cortex. Plants are therefore sustainably cultivated and continuously replanted, with no difference from what is done with poplar trees destined for papermaking.