Chromium Tanning Agents
What are leather tanning agents?
Tanning is the most important step in the leather production process. This is the part of the process where the skin is turned into leather. Tanners use certain “tannins” to stop the hides from decomposing. Tanned hides have a tannin concentration of 4 to 4.5%. The tannins are absorbed and stored in the tanned hides, where they break down the leather’s collagen fibers. A range of different tanning agents can be used to tan leather: vegetable, synthetic, and chromium tanning agents.
Extracting Chromium (III) Oxide
In contrast to vegetable tannins, mineral tannins are not soluble in water. Therefore, the water-soluble chromium salts have to be treated using a chemical process first. 480,000 tonnes of chromium tanning agents are produced each year, approximately 125,000 tonnes of which are chromium (III) oxide. Green chromium salt is now used in 85% of global leather production. In modern tanneries, wastewater that contains chrome and other waste materials produced during the tanning process is salvaged, treated, and recycled.
What is chrome-tanned leather?
Chrome-tanned leather is lighter and more sturdy than vegetable-tanned leather. This type of leather has a tannin content of 4%, which makes the skin easier to soak. This tannin is popular because it saves the tannery money, material, and time.
Chromium (III) Oxide vs. Chromium (VI) Oxide
Chromium (III) oxide does not cause allergic reactions in most people, therefore is considered harmless. However, chromium (VI) oxide can be harmful and should be avoided where possible. Chromium (VI) oxide can occasionally be found in leather products that have been incorrectly produced using chromium (III) oxide. The presence of chromium (VI) oxide can be prevented by using vegetable tanning agents or fatty agents in the tanning process.
Chrome-tanned leather at Gusti
All of our Gusti Leather studio products use chrome-tanned leather. Gusti’s main producers comply with international production standards, like SA 8000, when manufacturing the Gusti Leather studio range. We carry out regular tests to ensure that all of the leather we produce adhere to pre-determined chromium (VI) values. These tests are conducted by accredited labs in India, as well as by the TÜV SÜD (an independent company that tests, inspects, and certifies technical systems, facilities, and objects).
Check out the video below to find out more information about the different types of tannin:
Sources accessed December 15, 2022: