NO LEATHER WITHOUT TANNING

What type of chrome really is the bad guy and what is meant by vegetable tanning. Our thoughts on an emotionally charged topic. Is chromium better than its reputation? And: Is vegetable tanning always sustainable?

OUR LEATHERS
Every decision we make for CEDOUBLÉ is well-considered, responsible with a focus on sustainability in all areas and fits our pricing strategy. That is why we do not shy away from answering the obvious and understandable question about the origin and production of our leathers.

For our footwear and bags, our manufacturers source leather from state-of-the-art European tanneries that have many years of experience in their craft and are Gold-certified by the Leather Working Group (LWG). The Leather Working Group is a non-profit organization whose mission is to drive continuous improvement and transparency within the global leather manufacturing industry throughout the entire supply chain. The Gold certification is awarded to those members of the supply chain who submit to an on-site inspection over several days and demonstrate exemplary compliance with ecological standards. These ecological standards include the economical use of water and energy, correct waste and wastewater disposal, compliance with limits for noise and air emissions, complete traceability along the entire value chain, ensuring the health and safety of employees and the legally compliant handling of chemicals and regulated substances. In addition to the assessment by the LWG, some of the tanneries also work with private consulting firms specialized in the area of environment and thus regularly undergo an additional voluntary audit. Last but not least: All the leathers we use are finished with products that are water-based and solvent-free.

IT ALL STARTS WITH TANNING

The most important step in the leather production process is tanning because tanning agents ensure that animal skin becomes durable. They cross-link and fix the protein fibers, thereby preventing rotting or hardening. A distinction is made between chrome tanning, vegetable tanning and synthetic tanning. Since we are frequently asked about chrome and vegetable tanning in particular, the following is devoted to these two tanning methods.

NOT ALL CHROME IS THE SAME
Chrome is a naturally occurring metal and chrome tanning still the most common form of tanning (about 90% of tanning worldwide is done with chrome salts). And, if executed correctly, this is far less harmful than widely believed. Here we offer the thorough treatment of a topic that we as a shoe label can neither escape nor want to escape in this day and age. As we find that certain assumptions and fears are associated with the term chrome, we would like to place them in a larger context.

For example, the chromium III (trivalent chromium) used for tanning is basically harmless to health in the first instance and even occurs as an essential micronutrient in some foods. However, the harmfulness of chromium depends on its oxidation state. If improperly handled somewhere along the entire value chain from production through storage to the end of the product's life, chromium III can react to form hexavalent chromium compounds. And this is precisely what must be avoided as these can harm the environment and water as well as cause skin irritation or allergic reactions. According to the EU chemicals regulation REACH, leather products that come into contact with the skin must not exceed a chromium VI content of 3 ppm (ppm = parts per million) of the leather’s total dry weight. The good news is: How to avoid the formation of chromium VI compounds is now well researched. Furthermore, there are chrome tanning materials that are provided with additives that specifically counteract the formation of chrome VI.

The wastewater containing chromium III that naturally occurs during the tanning process must of course be treated and disposed of in accordance with regulations because it is hazardous to the environment. Since our manufacturers work exclusively with tanneries that have been awarded the Gold certification of the Leather Working Group, proper treatment and disposal of the wastewater is guaranteed. 

VEGETABLE TANNING
As an alternative to chrome-tanned leathers, leathers tanned with plant-based substances (often referred to as vegetable-tanned, organic or natural leathers) can be used. A so-called tanning broth is made from woods, barks, leaves, roots or fruits and used to preserve the animal hide.

The advantages here are good skin compatibility (suitable for people allergic to chromium) and biodegradability. However, this type of tanning also has a few disadvantages which, depending on personal preference, may have a greater or lesser impact on consumers. Acquired knowledge paired with our personal experience result in the following quite individual food for thought or perhaps an aid to forming an opinion:

  • Pure vegetable-tanned leather is often thicker, heavier (it absorbs a large amount of the tanning agents) and less tear-resistant (because it is more brittle) than chrome-tanned leather – however, improved suppleness can be achieved by combination or mixed tanning with chrome-III. Leather labeled as vegetable tanned was consequently not always exclusively vegetable tanned if it is not explicitly also declared as chrome-free (FOC). In addition: In our opinion, vegetable-tanned leather is not suitable for all types of footwear as it has a rather rustic appeal (and is therefore used, for example, for saddles, chair coverings, briefcases, belts and high-quality leather outsoles). Because of the lack of surface sealing, even the smallest (and normal) imperfections in the leather remain more visible, such as scars from insect bites or injuries sustained during the animal's life. Having said this, we know from ourselves and others a certain demand for perfection here, which is why even inconspicuous defects are not welcomed. This is understandable insofar as one has paid good money and understandably expects good quality in return. However, the following disclaimer applies even more clearly to vegetable-tanned leather: Leather is a natural product. In order to prevent complaints, vegetable-tanned leather is usually subjected to quite strict controls and batches with visual defects are sorted out. This is one of many reasons why vegetable-tanned leather is significantly more expensive than chrome-tanned leather, the appearance of which is easier to control and prettify with a surface sealant.

  • In terms of dyeing, vegetable-tanned leather offers a limited range of possibilities, so that many great color shades cannot be realized and trends implemented. It also does not always accept dyes evenly, is less color-fast than chrome-tanned leather and usually darkens due to exposure to light, moisture and greasing (this leads to a so-called patina which is known, for example, from the Vachetta leather components of Louis Vuitton bags). If vegetable tanned leather dries out, it becomes lighter.

  • Storing, cleaning and caring for this type of leather is a challenge as light changes the coloration and moisture causes irreversible stains. Think here of sudden onset of rain, perspiration on the feet in the summer or even just the use of water for cleaning purposes. On the other hand, uncoated natural leathers can also stain things they come in contact with more quickly (especially when damp) because they are open-pored and hold color pigments more poorly than chrome-tanned leathers. The best way to care for vegetable-tanned leathers is with leather grease. This keeps them supple, has an impregnating effect and can help to make water stains less visible (which cannot be completely removed from vegetable-tanned leather) as the leather product as a whole becomes darker. But not only consumers need to understand the nature of vegetable tanned leather products, retailers should store and present their goods in a way that protects them from light, for example, as well.

  • The vegetable tanning process is labor-intensive, requires a high level of expertise and takes several months for a truly pure vegetable tanning without any chrome or synthetic tanning agents while chrome tanning is much faster at only 1-2 days. The process also requires more energy and water as well as a large amount of tannins (about 20 kg of fruit or 90 kg of oak wood per cowhide, for example). Some tannin-containing plants have to grow for many decades before a sufficient amount of tannin is produced. In the interests of sustainability, therefore, attention should also be paid to the origin of tanning agents in vegetable tanning since many of them do not have a sufficient supply to meet the needs of global leather production.
In summary, from our perspective it can be said that neither should responsibly conducted chrome tanning be demonized nor vegetable tanning be glorified unconditionally. From our experience and the extensive research that we have once again undertaken for this article, we take away that a differentiated approach makes sense. Currently, chrome-based tanning is the most suitable alternative for us as this is the only way we can bring very durable, easy-to-store and easy-to-care-for products to the market that can be enjoyed for a long time.

However, we can assure you that we will continue to inform ourselves and look for other environmentally friendly materials in the future. We just do not believe in using vegetable tanned leather for marketing reasons alone. Feel free to share your thoughts on this topic with us – we welcome feedback, food for thought and also a little input on, for example, pricing or willingness to pay - would you consider to dig a little deeper into your pockets for FOC vegetable tanned leather products?

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