(3 minute read)

I’m sure you’re aware that the quality of leather products can vary significantly - but do you know why?

I’ve heard so many stories of expensive wallets and bags that have fallen apart after a year or less. Even when properly cared for, some leathers seem to wear out far more quickly than others. What causes this to happen?

For the most part, it boils down to how the leather is processed.

Animal hides of any kind are tanned in order to create leather. In essence, the tanning process removes moisture from the hide, allowing it to retain it’s natural resilience without deteriorating over time.

But you can’t just dry a hide out in the sun. This results in an inflexible finished product that is prone to cracking when bent. Instead, we (the human race) got a little bit clever several thousand years ago, and developed a method that worked.

Vegetable-Tanning

As the name suggests, vegetable tanning uses naturally occurring tannins to dehydrate the hide. If you’ve ever been on a wine tour, chances are you’ve heard the word ‘tannins’ used in relation to red wine. Remember the last time you saved the queen from drowning at a BYO, and your mouth felt dry? That was the tannins.

While the tannins in red wine come from the skin of the grape, the tannins used in the vegetable-tanning process are obtained primarily from tree bark.

You can actually see the collagen structure if you look closely at high quality leather

These tannins bind to the collagen fibres that make up the hide, replacing the water molecules. This leaves the finished article both flexible and immune to the ravages of time.

As technology has developed, so too has the vegetable-tanning process. Recipes have been refined and perfected to produce a wide variety of leathers. But developing technology has also introduced new processes for tanning.

Chrome-Tanning

Around 150 years ago, it was discovered that chrome ions could be used in place of vegetable tannins, leading to the development of chrome-tanning.

This discovery drastically reduced the time it took to produce leather, and brought the cost down as a result. While vegetable-tanning is very hands-on and takes around a month per hide, chrome-tanning can be fully automated, and takes a matter of days.

An old-school American tannery

Naturally, the efficiency and cost savings meant that chrome-tanned leather quickly became the norm. As of today, more than 90% (some say 95%) of the leather produced globally is chrome-tanned.

The Difference

Both tanning methods have their upsides and downsides.

Vegetable-tanning is an intensive process, and the price of vegetable-tanned leather is typically more than double that of the chrome-tanned equivalent. In addition to this, vegetable-tanned leathers are limited to natural, earthy colours whereas chrome-tanned leathers can be dyed any colour imaginable.

Traditional vegetable tanning at the Böle Tannery in Sweden

So why is it that despite these limitations, 10% of the world still choose to use vegetable-tanned leather?

Firstly, chrome-tanned leather doesn’t last. Because the chromium salts penetrate the leather so quickly, the leather’s structure is destroyed in the process. This results in a thinner, softer leather that will crack and disintegrate with use.

Workers in a chrome-tanning facility in Kanpur, India.

The chrome-tanning process is also harmful to the environment. Chrome-tanned products need to be replaced frequently, and because this leather is non-recyclable, it means more waste going into landfills.

Additionally, because it is so cheap, chrome-tanning often takes place in developing nations. Workers in these facilities are exposed directly to the Chromium and other chemicals and acids used to tan the leather. Aside from being a known carcinogen, Chromium can cause respiratory illness and severe burns.

Given the choice between chrome-tanned and vegetable-tanned leather, it was a no-brainer for Sonder Leather.

The Clear Choice

If I can use the wine analogy one more time; vegetable-tan is the Penfolds of the leather world, while chrome-tan is the Obikwa.

 Sustainable vegetable-tanned Kangaroo leather in all it's glory.

Sonder Leather’s mission is to inspire an appreciation for craftsmanship by producing heirloom quality products. Because of this, it makes sense that every product we make is crafted exclusively from sustainably sourced vegetable-tanned leather.

Vegetable-tanning may not have the rapid turnaround time or attractive price-point of chrome-tanning, but the leather it creates is rich in character, and will only improve with age.

Thanks for reading, and I hope you’ve learned something valuable. If you’re wondering how to tell whether leather has been vegetable-tanned or chrome-tanned, here are a couple of giveaways:

• The smell that you associate with leather is the smell of vegetable-tanned leather. It is sweet and earthy, whereas chrome-tan smells like chemicals
• Shallow scratches will stay on chrome-tanned leather indefinitely, but can be buffed out of vegetable-tan fairly easily