In recent years, even decades, the leather industry has caused many environmental hazards across the globe due to its chemical nature of material production. This dire state of affairs prompted scientists to refine both new and old solutions to manufacturing practices that will mitigate the negative effects on our ecosystem. The result of this extensive research pointed to vegetable tanning - an organic form of tanning the leather that uses a mixture of bark extracts, organic dyes, and fat liquors instead of chromium salts and other metallic based solutions.
Vegetable Tanning Vs. Chrome Tanning
Vegetable tanning is no recent discovery. This method has been used for thousands of years, since the dawn of civilization. If you need any proof, a fully-preserved leather shoe was recently found in Armenia and it is estimated to be 5,500 years old - 1,000 years older than the Great Pyramid of Giza in Egypt!
Just as the name suggests, this traditional method’s efficiency relies on vegetable tannins from oak, mimosa, or chestnut barks as well as other plant tissues found in nature. The only downside to this method is that it takes time, lots of it. The fashion market demand was barely met until newer and faster tanning methods were invented in the mid-19th-century. Such discoveries led to the use of minerals such as chromium sulfate that not only prevents skin decomposition by binding chrome salts to the collagen protein but cuts down production time drastically.
Today, chrome tanning is responsible for more than three-quarters of leather production worldwide. Why? Because in less than a day, this method can produce flexible water-resistant leather that maintains its glossy finish throughout its “lifespan”. It is low-cost, efficient, and produces high-quality materials, but the use of heavy metal minerals during manufacturing wreaks havoc to our environment as a direct consequence.
Benefits of Vegetable tanning
- Thickness and resilience
- Traditional production methods
- Feels “alive” to touch
- Smells “earthy”
- Develops patina with use and age
The Process of Making Vegetable Tanned Leather
During Spring, oak bark is stripped from the trees and dried for 2-3 years. Later they are broken down in 2-3 inch bits and chips, which provide that necessary raw material for the tanning yards. To extract the tannins, oak bark is mixed with cold water so imagine you are making a big cold-brewed pot of tea or coffee. When the tan strengthens, the hides are dipped from one pit to the other on a weekly basis, each stronger than the recent. After about three months, the hides are done with the strongest concentrations, layered on top of one another like sandwiches, and left in the pit for another 9-12 months.
Yes, truth be told, this is a very slow process working with tree bark tannage, but the end result is hard-wearing leather with exceptional tensile strength. Most importantly, no minerals or heavy metals are required to make them, sparing both people and nature of health and environmental hazards.