A particular advantage of Think! shoes is the use of chrome-free tanned leathers for the lining. The tanning of the leather takes place in Germany and Italy and is tested at regular intervals by an independent institute for technical chemistry.
Instead of treating the leather with chemicals, Think! uses almost solely tanning-rich parts of plants, for example bark, wood, leaves, fruits, etc., to tan the material. A distinction is made between hydrolysable (acid-forming) and condensable (sludge-forming) tanning agents. Hydrogen bonds provide the necessary bond between the tanning agent and the collagen. The large number of these bonds makes the tanning process relatively stable.
