I wanted to write a short blog post to explain why I believe vegetable tanned leather to be so superior when choosing leather for a watch strap. Before getting down to answering that question, however, I realised that it might first be useful to briefly explain (1) what is “tanning” leather, (2) why do we need to tan leather at all, and (3) what methods for tanning leather are in use today. So let’s start with the basics….
Why do we turn animal skins into leather?
For thousands of years, humans have hunted animals, primarily for meat, but the skins were also highly prized. Rather than simply a byproduct, animal skins were cherished – they are strong, flexible, and have excellent insulating properties. Without tanning, however, raw hides would quickly decompose, stiffen, and rot. The tanning process effectively stabilises the material and makes it durable, supple, and resistant to decay. By tanning animal skins, they are transformed into a material that can be used to produce valuable goods such as clothing, footwear, and tools, whilst at the same time ensuring that no part of the animal goes to waste. It can therefore be argued that leather tanning has played a crucial role in human history, preserving hides and enhancing their usefulness across cultures and industries.
Are there different methods of tanning leather?
The practice of leather tanning dates back to ancient times. Archaeological evidence suggests that early humans used rudimentary tanning methods as far back as 5000 BC. The Sumerians, Egyptians, and Greeks all had established tanning techniques, using natural oils, fats, and smoke to treat hides. By the time of the Roman Empire, vegetable tanning, with tannins extracted from tree bark, became widely adopted, and it was found to produce a more durable and flexible leather. During the Middle Ages, tanners formed guilds and refined their methods, with European countries like Italy and Spain becoming renowned for high-quality leather production. The Industrial Revolution in the 19th century introduced chemical tanning processes, particularly chrome tanning, which drastically reduced the time required to produce leather. However, traditional vegetable tanning has persisted, especially in high-end leather goods.
Today there are 5 main methods used to leather:
1. Vegetable Tanning
Vegetable tanning is one of the oldest methods, using tannins extracted from tree bark, leaves, and other plant materials. This method creates firm, biodegradable leather that develops a beautiful patina over time. While it is eco-friendly and produces a strong & durable leather ideal for high-end leather goods, the process takes many weeks and often months, and is therefore an expensive way to produce leather.
2. Chrome Tanning
Developed in the mid-19th century, chrome tanning is the most widely used method today, accounting for nearly 80% of all leather production. It involves the use of chromium salts, which accelerate the tanning process and produce soft, flexible leather with high durability and resistance to water. The process is very quick, taking about a day to complete, and although modern tanneries have improved their working practices a lot over the last 30 years, there are still some environmental concerns due to the use of heavy metals.
3. Aldehyde (White) Tanning
Aldehyde tanning, also known as white tanning, uses aldehydes like glutaraldehyde or formaldehyde to create ultra-soft, lightweight leather. This process is commonly used for making chamois and automotive leathers. It is metal-free, making it a more environmentally friendly option than chrome-tanned leather, but the leather produced is not as durable.
4. Synthetic Tanning
Synthetic tanning, or “syntan,” uses artificial tanning agents to create a variety of leather finishes. This method is often combined with other tanning processes to improve leather quality. It provides consistency and can be designed to meet specific industry requirements, but there are some environmental concerns with some of the synthetic tanning agents.
5. Brain Tanning
An ancient and traditional method, brain tanning involves using animal brains and fats to tan hides. It produces soft, breathable leather with a unique texture, commonly used by indigenous communities for making garments and accessories. While completely natural and chemical-free, this labour-intensive process is not widely used in commercial production.
The various different tanning methods will all produce leather that is stable and resistant to decay, so does it matter which we use?
So now we get to the question of why I feel that vegetable tanned leather is the right choice for your next watch strap, and why I will always choose a vegetable tanned leather over a chrome tanned leather. Due to the speed that leather can be produced, chrome tanned leather is generally much cheaper to buy, but there are some specific advantages to vegetable tanned leather that make it the best choice, in my opinion –
Durability & Strength. The vegetable tanning process may be slow & expensive, but it results in a stronger leather that is both firm & flexible.
Patination. One of the most desirable qualities of vegetable-tanned leather is its ability to develop a rich patina over time. Chrome tanned leather is far more resistant to patination. In my opinion, vegetable tanned leather has soul!
Eco-Friendly. Vegetable tanning avoids harsh chemicals like chromium, making it a more environmentally sustainable choice.
Breathability & Comfort. Unlike chrome-tanned leather, vegetable-tanned leather remains breathable, making it more comfortable to wear and therefore far more suitable for a watch strap.
Hypoallergenic Properties. Without toxic chemicals, vegetable-tanned leather is far less likely to cause skin irritation, making it ideal for anything that comes in direct contact with the skin. This is a prime concern when making watch straps, for obvious reasons!
Artisan Appeal. Vegetable tanning is a traditional craft, and garments made from this leather often have a unique, handcrafted quality that is highly valued in fashion and luxury goods.
The Process of producing vegetable tanned leather
Preparing the Hides – The process begins with raw animal hides. These hides are cleaned to remove any flesh, fat, and hair, leaving behind the raw material ready for tanning.
Soaking in Tannins – The hides are then submerged in large vats filled with a tanning solution derived from natural plant extracts. This step can take weeks or even months as the tannins slowly penetrate the hide, stabilising the fibres and transforming it into leather. Once the tanning is complete, the hides are thoroughly washed to remove any residual tanning agents.
Drying and Conditioning – The hides are now carefully dried to remove excess moisture. At this stage, they may be oiled, waxed, or conditioned to enhance their flexibility and longevity.
Finishing Touches – The final leather can now be dyed, embossed, or finished with natural oils to achieve the desired look and feel.
What is “patination”, and why is it so desireable?
One of the most desirable qualities of vegetable-tanned leather is its ability to develop a rich patina over time. Unlike synthetic or chemically treated leather, vegetable-tanned leather reacts organically with its environment, absorbing oils from the skin, exposure to sunlight, and the effects of daily use. This process gradually darkens the leather and enhances its character, creating a unique and individualised appearance. A well-developed patina enhances the character of leather goods, giving them a vintage, well-loved look.
Patination not only improves the aesthetic appeal of leather garments but also adds to their longevity. As the leather softens and conforms to the wearer’s body, it becomes more comfortable while retaining its durability. This natural ageing process makes vegetable tanned leather an investment that improves with time, making it a preferred choice for those who appreciate quality craftsmanship and long-lasting materials.
Conclusion
So, as you can see, leather tanning has come a long way from its ancient roots, with various methods catering to different needs and industries. While chrome tanning dominates the market due to its speed and cost-effectiveness, vegetable tanning remains a preferred choice for high-quality, environmentally conscious leather goods. With its rich history and sustainable attributes, vegetable tanning continues to be a timeless and respected technique in the world of leather craftsmanship.
There is one more reason to consider also – only the best hides are used in vegetable tanning. This is partly due to the fact that vegetable tanning is a far more expensive process, so to realise the best return on the best hides, the tannery will normally select them for vegetable tanning. The reverse is also true – there is little point in putting inferior quality hides through a process that, because of the time it takes, results in a more expensive end product.
Almost all of the leather I use is vegetable tanned. When choosing a leather for a watch strap, there simply isn’t any doubt in my mind – vegetable tanned leather is the best possible option. Not only is the leather strong, pliable, breathable, and long-lasting, but it will develop a lovely patina with some wear.
At the beginning of the year I posted on Facebook asking for any suggestions for blog content, and many of you emailed in questions that you’ve asked me to answer in this blog. I will try to work through them, but this blog post is written in response to a question asked by a customer, Ollie from Longueuil, Canada, who asked me “Can you explain why you have a preference for vegetable tanned leather?” I hope I’ve answered your question, Ollie.
It’s not too late to ask me something. If there is anything you want to ask, email me at rich@toshi-straps.co.uk and I’ll consider writing a blog post to answer it in the future.