What are the differences between Vegetable Tanning and Chemical Tanning?
We have recently released some certified vegetable tanned leather straps here at WatchGecko. They are made from genuine Italian Leather that has been treated using only vegetable matter and plant extracts rather chemical substances.
First of all, tanning is the process of treating leather so that it can be used to make products. It stabilises it and stops the leather decomposing, makes it more durable, but also pliable and will sometimes colour the leather before it can be made into other things. Leather has been used for thousands of years to make clothing, water carriers, shoes, armour and so on. There are two most popular types of tanning processes, one being chemical or chrome tanning and the other being vegetable tanning. I want to discuss the differences between these two processes and the advantages and disadvantages of each one.
The tanning process
Hides need to be prepared before they can be put through the tanning process. This includes removing hair, de-greasing and importantly soaked in salt to kill bacteria which stops the processes of putrefaction and absorbs moisture within the hide; this is called Curing. Curing can be done either by placing the hides in salt and sealing them for a month or so or soaking them in brine baths. They are then ready to be immersed in a tannin bath. The aim of this bath is to turn the hide into a durable, pliable product to work with. It stops the hide from putrefying and decomposing over time and gives the hides rich hue colours and shades.
This is where the chemical or vegetable aspect comes in. The bath will either contain natural vegetation to treat the hide or it will be a chemical bath. The vegetable soak takes a longer period of time (sometimes months) to affect the leather because of its lower concentration, whereas the chemical version can be done in 24 hours because of the stronger acidic ingredients.
So what are the differences between Vegetable tanning and chemical tanning?
The clue is really in the name. Chemical tanning includes a variety of chemicals, with the most traditional one being 'Tannin' (where the name comes from) and 'Chromium' which was used by tanners in the industrial revolution. This is also a quicker process of tanning hides, so it has been adopted by many companies due to the ease and turnaround of treated leather. This method creates the same end result and the appearance of the leather will continue to stay the same for a long time after.
Vegetable tanning uses natural materials and substances to treat the leather. 'Tannin' can be found at varying levels of concentration naturally in vegetables and other plants which is why this process is successful. It is an extremely old and traditional method that doesn't just use vegetables as the name suggests but tree barks and other natural substances to create rich, warm and earthy tones that are different every time. People with chemical sensitivities might find this particular method much more suited to their skin but it would need to be researched to ensure it's tanning origins. This method creates different end results each time and the appearance of the leather is much more akin to its former self, with lines and creases and forms a natural patina over time but with added durability and longevity.
Advantages and Disadvantages
- It is a very quick process that takes little to no human interaction and uses vast machinery
- Can get bold, bright and vibrant colours that vegetable tanning cannot achieve.
- Colours will remain solid and uniform throughout the strap
- The Environmental impact is very high because of the use of chemicals that cannot be disposed of easily
- The Leather stays untouched for many years and doesn't form patina as vegetable tanned does
- Loses some natural character when it is tanned
- The chemicals used in this process can upset skin
- It takes a long time for skins to be tanned in this way sometimes a period of months
- Vegetable tanning gives each piece individual characteristics and there will always be a different end result
- This method is based on ancient tradition and takes a skilled tanner to treat using this method
- The colours aren’t so striking and bold with vegetable tanning, but create earthier natural tones.
- This method gives the leather a natural patina over time and ages with the user
- The environmental impact of this method is much lower and tanning fluids can be disposed of easier than chemical tannin
- Using natural matter helps towards anti-allergenic leathers with no chemical sensitivities
Here at WatchGecko we have some vegetable tanned straps that have been certified by Pelle Al Vegetale in Tuscany. The certification ensures that the tanning methods are done to the highest quality and that they are done according to traditional methods. They also ensure that the hides used within the tanneries that they monitor are from animals that have been used in the food industry and not killed for their skins alone (something we also look out for with our regular tanned leathers).
You will see the Pelle Al Vegetale handprint printed onto the underside of our certified straps.
These straps have rich and full colours and really hold a lot of character and will age well with the wearer by forming a natural patina over time. They can be used with some great dress watches to add subtle class and simplicity or more rugged veg tan leathers can give a vintage watch a lot more character.
As mentioned previously, the colours with vegetable tanned leather are much more natural and earthy (a result of using a natural process) and stick more within the autumnal colour range, with browns, warm ambers, beiges and reds. They hold a timeless look, pairing well with vintage watches to continue the classic textures and styles or pairing well with newer models to add character and simplicity.
This strap is our Vegetable Tanned Gillingham by Geckota. It has carefully cut perforations to give it a classic racing style, neat contrast stitching detail at the top of the strap and comes in three earthy colours. This particular image is our light brown colour, which pairs beautifully with the Tudor BB because of the guilt painted dial features; it makes for a great coordinating wrist-watch.
Next up is our Vegetable Tanned Cottingham by Geckota which is one of our more slender straps. The narrow size and subtle pattern on this strap make for a delicate addition to a watch and makes a statement without being too bold. Pairing particularly well with small vintage watches such as this gold Timex because of its size. It adds texture but stays minimal on the wrist.
This is the Vegetable Tanned Otley with added padding. It is a slightly thicker strap, which would go well with chunkier watches and remain comfortable on the wrist. Again, this Tudor BB and Otley pairing look great, as the black continues throughout and the creamy stitching of the strap complements the gold dial features. The Otley in black adds sophistication and would dress up a watch whilst keeping the character.
Finally, this strap is the Vegetable Tanned Tetbury by Geckota. This is the only veg tan strap that has matching stitching, creating a smooth continuous style. It looks elegant with dress watches with its subtlety and sleek character.
Overall, there are pros and cons to vegetable and chemical tanned leather and deciding which process will suit your leather depends on a few elements, but mainly what finish you would like at the end.
The vegetable tanned leather is a joy to wear because of how it ages with the wearer, forming natural patina and developing character. On the other hand, the bold and vibrant colours that you can achieve with chemically tanned leather is hard to beat; perhaps you want to make a statement and bring a pop of colour on your wrist that won't fade. It does depend entirely on usage and preference, so it is good to research your leathers before working with them or purchasing them.