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The ins and outs of Vegetable Tanning

September 27, 2022

I have three things to say about leather: I am an omnivore, I like Christmas trees, and I hate waste. What does this have to do with leather? These are three essential facts about me that are at the foundation of what I believe about leather, why I love it, and why I think it is a wonderful, amazing material.

On Food and the Omnivore

A beautiful plate of food in a bistro

First, I am an omnivore. I enjoy a good diet, including fish, meat, fruits, and vegetables. I believe that this is the ideal diet for humans. I am fortunate to live in a place and in a way that affords me access to these foods. Moreover, my Italian heritage informs the importance that I place on not just food but the meal with its small rituals. In our family, we eat the evening meal together, and we all agree that it is worth pushing back on the pressure for dinner to take a back seat to the other demands of busy lives. It is a choice and an important one. If you are lucky enough to have food, friends, and family, enjoy them, and savor each bite and each minute. The meal is where you do that. (I also really like coffee and a nice glass of wine. We'll get to that later.) Though I limit my meat consumption, I believe it is and should be part of our diet. For our family, it is an excellent source of protein and enjoyment. Leather is a by-product of the food that we take. By making and using leather, we efficiently and respectfully take advantage of the full bounty of the livestock.

Bosca Christmas tree

On Christmas Trees, Farms, and Family

Second, I like Christmas trees. Every year, we go out as a family to cut a fresh Christmas tree. Sometimes we are asked if it bothers us that we are cutting a tree down. It does not. Christmas tree farms are still primarily family-run agriculture businesses. (Image of Mr. Christmas Tree) I like supporting that. Christmas tree farming is also very low impact. These farms keep hundreds of thousands of acres of land in productive use, absorbing carbon dioxide and pumping out oxygen. I feel good when I support these tree farms.

French Cows

Our own supply chain starts with small family-run cattle operations in Northern France. These are rustic farms owned and run by people who use their hands and do the work of farming. I feel good about supporting these businesses; they produce the best raw material for the finest leather on earth. These are dairy cows who lead very good lives. (This also means that our work is related to some very lovely cheeses, which I also happen to like!!) I feel very good about supporting these agricultural businesses.

Waste not…

Finally, I hate waste. Well, who doesn't really, but sometimes it takes a back seat to other things that seem important. Fashion, especially "fast-fashion," can be wasteful. Products are designed to last a season at best and quickly end up in a landfill. Both budget and luxury fashion and accessories can be wasteful in different ways. We feel that our approach is correct. We focus on making a product that is designed to be fresh but timeless. We then put our efforts into executing that design so that the product would last many years. For many of our products, at the end of a long and useful life, they can serve as compost, rather than as true landfill.

My father, Mario Bosca, was one of the early adherents to "reduce, reuse, recycle." He really tried to apply these rules to what he did, and we follow that philosophy. That always leads us back to vegetable-tanned leather. Our leather reduces waste by using the bi-products of our food chain. Vegetable tanning completes this philosophy by giving us a material that will last a long, long time. Finally, the leather is fully biodegradable at the end of the product's useful life. Waste not, want not.

Tanning and Tannins

Tanning is the process of turning an organic and renewable raw material into a stable, useful material that will last for many years. The word tanning comes from the word tannins. Many kinds of wood and barks are sources of tannin. Tanning is also possible using other processes, including uric tanning, chrome tanning, and syntan. They tend to be used in more industrial products, however. At Bosca, these are not our first choice. While a part of the Bosca line uses chrome-tanned leathers, we focus primarily on vegetable-tanned leather.

Vegetable Tanning

Vegetable tanning is a particular way of tanning that uses tannins derived from natural, organic sources. Our leathers are primarily tanned with compounds that come from chestnut. In our opinion vegetable tanned leather is the best leather for almost everything, and leather made with chestnut-derived tannins is the best leather for handbags, brief bags, backpacks, and wallets for men and women. Our belt line uses a variety of full-grain top leathers, but for the back of the belt (called the lining), we use vegetable-tanned leather made with tannins derived from the mimosa tree. These tannins create a tighter, more dense leather.

Vegetable-tanned leather is what most of us recognize as "real leather." This is the leather with a delicious aroma and a bit of a "squeak" when you work it with your hands. It is also the oldest method originating in Europe. Tannins bind proteins in the hides, making the material resistant to bacteria and decomposition. That means that the material is stable and will last a long time.

Certified Italian Vegetable Tanned leathers do not contain any other chemicals, chromes, heavy metals, or pentachlorophenol, as is possible with different leather types.

Throughout the vegetable tanning process, bi-products are used in fertilizers and construction materials. Almost no part of this valuable, renewable resource goes to waste.

At the end of the (hopefully long) life of your Bosca product, the vegetable leather can safely biodegrade without any adverse ecological consequences.

Interestingly tannins are naturally occurring in coffee, tea, and wine. At least two of these beverages are at the top of my list of favorite things. Tannin is an astringent. This creates the mouthfeel from a coffee (especially a really good espresso) or a sip of good wine. The tannins are also responsible for how some wines (at least those made with traditional methods) will age and improve with time, much like our Bosca hand-stained leather. Tannin probably tastes horrible on its own, yet at least in my imagination, I see the thread that ties these things together. They all catch our attention and beg us to stop to appreciate their effects on our senses- sight, smell, and even, in leathers case, the sound. Coffee, wine, and leather all seem to encourage the same appreciation that calls to us from a pleasantly dark, woody place, somewhere a bit mysterious. All are pleasing in ways that go beyond function.


After tanning, the hides are leather. They are stable. But a tannin is an astringent, so this pulls the proteins of the leather together. This makes the material quite stiff and rigid. Several processes follow, which give the leather the specific characteristics needed for the intended purpose. Our leathers are dried to a precise moisture content, then an exact amount of organic oil is added. This is followed by tumbling to soften the leather to give it just the right "temper." The "temper" is the balance of all the characteristics. Making the leather right for our product combines art, science, and an experienced hand.

Raw Materials

Our hand-stained Italian vegetable-tanned leathers start with farms in Normandy and Brittany, two regions that run along the north coast of France. These regions are primarily rural and pastoral, dotted with numerous tiny towns and villages. Cattle farms here pursue the typical French penchant for independence. Most are small family operations. Like our Italian tanneries, these family farmers have learned to use coops to concentrate their investment in modern facilities for processing high-quality milk and agricultural products. These animals have an excellent diet, health, and care. They are exposed to a minimum of insects. They are not exposed to extremes in weather and, interestingly, are raised in fields demarked by hedges and motes. This is a big help in keeping injuries to a minimum. This means a minimum of scars and scratches on the final leather product. Remember, though- we consider those natural markings part of the natural beauty of leather.

We believe that raw material from Normandy and France is the finest available anywhere and certainly the best for our product as it is designed and engineered. Hide of a good quality certainly can and does come from other areas. Holland, for instance, is an important source of rawhides. However, leather produced from these hides yields a more dense and still product; not what our designs call for.

The Italian Tanning Industry

The tanning industry in Italy is essential, and it is valued by their government and society. Our leathers are produced in a town between Florence and Pisa. There are two such towns that straddle the Arno River. Most of the businesses in these towns are tanneries, or they are businesses that serve the tanning industry. The structure of this industry is highly cooperative in both the formal and informal senses. Our "tannery" is a network of separate companies that do the work at different stages of the process. The central part of this collaboration is the tannery, where the raw material is converted to leather. Other companies, however, are enlisted to do staining, ironing, splitting, buffing, or whatever work may be needed. A day "at the tannery" is a day spent running over to see Bernardo where the spraying is done, then back over to see Antonio where the hand-staining is done. On the way, we may stop to see Ibra at the plating plant. The good news is that everything is within a kilometer, so there is little waste in doing the work this way.

Chris Bosca and an associate review leather

One indispensable service is the use of the coop water purification system. This is one of the reasons why the tanning industry is concentrated in a few towns in Italy. Tanning does generate some effluents that need to be cleaned before the discharge of the purified water. Even just the higher acid/low ph effect of the natural organic tannins needs to be rebalanced. The Italian tanning industry is serious about eliminating harmful outputs. They are also incredibly creative in using every bi-product of the raw material and the process. In Italy almost every output goes to productive use.

Bosca tanning facility in Tuscany Italy

Why Italian Leather?

Why do we talk so much about Italian leather in particular? We support the Italian tanning industry's clean, sustainable, and circular approach. There is a strong industry association supporting these values. More information can be found at: We believe Italy produces the best leather for bags, belts, wallets, and other personal accessories. For our line, in particular, we use exceptional hand-stained leathers. But why Italy? How is it that they make the best leather anywhere? The answer is that they do it because they want to. It is because of the cultural status of the artisan. It is because it is in their DNA and culture to make a beautiful thing, to take the time to do it right.

Italian tanneries and machinery producers have exported their equipment and, indeed, their technology and techniques the world over. What they have not exported, however, is the culture. They have not exported the societal respect for a small producer- the artisan- working hand-on with their product to make a thing of excellence. In theory, anyone can make the leather that we make. It could be made anywhere in the world. In practice, it is very hard. It is hard to do it one time. It is harder on the order of magnitude to do it many, many times, for nearly 50 years. The funny thing is it does not get easier. It is hard but always worth the effort. The Italians know what they stand for, and we stand with them.

I am in Italy for about 3 months of the year. A lot of that time is spent at the tannery. We spend a lot of time working on new leathers, colors, and finishes. A lot of time and energy goes into keeping this one the way it should be. There are long conversations, maybe arguments, and possibly even some little fights. (It is so exhausting that sometimes we must stop for an espresso in the middle of a battle!) All to parse out what is happening- is it the new hides? Has the warmer weather had an effect? Has the tramontana wind charged the electrical particles in the air with an impact on the finishing? Is the hand-staining tending a little too dark or a little too light (it can never be an exact match) And so it goes?

In the end, it is always worth the effort.

At the End

We inspect hides before tanning, after tanning, after drying, and then one last time after all the staining and finishing has been completed. I personally inspect the leather before it is approved for production. If there are problems, we have to troubleshoot. We usually make corrections, but sometimes a batch must be rejected. Don't worry, it will be used to make some lower-quality leather with more pigment applied to the surface, but it will not be made into a product for the Bosca line. I inspect a lot of our leather in late fall and late winter. This means long days on my feet in the tannery where there is no heat. I really earn my glass of wine on those days. I look at every hide, mark it with a grade, and stack the hides in separate piles. As the day progresses, the piles move from one side of the room to the other. Sometimes in the middle of doing this, I wonder if that is the best use of my time, the best use of my life. Remember: I do not like waste. In the end, I decide that it is worth it. It is worth it to take the time to do this right. I also find that ideas can percolate and form into essential concepts in the zen of this work.

Christopher Bosca inspects leather

When you use your Bosca product, you will notice that the leather "wears in, not out" By this, we mean that the leather softens and develops a warm patina. Nothing lasts forever, but it should become more beautiful throughout the product's life.

At the end of your Bosca product's long life, the vegetable leather can safely biodegrade without any adverse ecological consequences.


Other interesting facts- foods and tannins

Coffee, tea, and wine all contain tannins. The British always say that a good cuppa (tea) makes everything better, I have experimented, and I believe that they might be correct, but if the tea or coffee doesn't work, the wine will.

Pouring wine in Florence Italy

I cannot claim to know much about tea, but I have a casual knowledge of coffee and wine. All three seem somehow related to leather. They appeal to our senses in the same ways; taste, appearance, and sound. All are highly variable natural materials. In all three, the best examples require time, dedication, and a stubborn passion for doing something right.

Coffee and wine are both staples of daily life in the Tuscan countryside. And not just any coffee or wine. People pay attention to what they eat and drink and have opinions!! There are other ties between the area's foods and the magic of vegetable tanning. One such thread of commonality is a seasonal treat called castagnaccia.  Castagnaccia is made with chestnut flour, the source of the tannins we use in our Old Leather and Dolce Leather...

Many days for lunch, when working at the tannery or the factory, I take lunch at Ginannini's in Fucecchio. The same cast of characters is always there, and the welcome is always warm. Although there is now a nice tavalo caldo where one can enjoy a pasta, some vegetables, and a roast of some sort, we usually have focaccia or panino (maybe two if we have really been working up a hunger.) After our sandwich, we always have a coffee. Sometimes, and especially in the autumn, we also have a piece of warm castagnaccio. This unleavened pastry is part of the canon of the "cucina povera" The chestnut has, since time immemorial, been a food of the poor and rustic people of Tuscany. During stormy periods like WWII, when there was little food of any kind, this sustained the people of the countryside. This treat is surprisingly rich, not too sweet, and sneaky. The more you eat it, the more you like it…like so many things Italian.


Castagnaccio (you can find it throughout the Region): one of the most famous Italian desserts is Tuscan Castagnaccio: a flat cake made with chestnut flour, water, extra virgin olive oil, walnuts or pine nuts, and raisins. They say in the winter, it warms the heart and fingers (since you don't need a fork, but just your hands to eat Castagnaccio.


  • 250 gr chestnut flour
  • 50 gr sultanas (raisins)
  • 80 gr pinenuts
  • 4 tablespoon Extra Virgin Olive Oil
  • 2 tablespoon sugar


  1. Mix in a large enough bowl with a fork flour, sultanas, sugar, and olive oil. Then add some warm water until you obtain a thick batter.
  2. Take an oven dish and oil it slightly. Pour the batter in it, then sprinkle it with the pinenuts and, if you want, with some rosemary leaves. Bake in the oven at 200 degrees Celsius (390 Fahrenheit) for about an hour.
  3. Best eaten slightly warm.
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