'Tanning' is making the cotton nets and sails more sustainable. After all, water and cotton tolerate each other badly, so that through the ages, methods have been sought to protect cotton from rotting.
In ancient times, for example, an extract of oak bark was used. Since the beginning of the nineteenth century catechu has been used. This is an extract from heartwood and the bark of various tropical trees, such as the acacia catechu, from the countries 'Behind' Indonesia and Borneo.