Report – Gerberei Martin, traditional oak bark sole leather tannery

Gerberei Martin is perhaps the oldest still existing tannery in the world, founded in 1645, and run by the same family ever since. They make the most traditional oak bark tanned sole leather around, with at least 24 months in the pits resulting in extremely durable leather soles, and have a highly interesting old-school approach to the whole business. Shoegazing paid them a visit.

One reach the small city of Tuttlingen on winding roads through the mountains of Black Forest. At the end of a street with a mix of industrial buildings and village houses, right next to a small river, there’s some pale white buildings among the trees. On one of the walls there’s a modest sign, stating Gerberei Martin. Gerberei is German for “tannery” – and this is one such which was founded in 1645. 376 years ago. Here the 10th generation of the Martin family is continuing the tradition with tanning leather, and they do it in a very traditional way. When I pull up there’s a local farmer outside the entrance who has a barrel with a few cow hides in it, and Manfred Martin, 73, and his son Thomas Martin, 40, takes a quick look and gives the farmer a price, which he accepts with a handshake. These hides are then salted and placed on a pile with other hides from local farmers, to be thoroughly inspected and sorted later on.
– It’s good to be able to source some stuff from local people here, the quality of the hides are often quite good for what we do. But it’s just small quantities, our main supply of hides we source from Austria, Bavaria [the German region Bayern] and occasionally some other places, Thomas Martin explains.

The premises of Gerberei Martin.

Thomas Martin.

Manfred Martin.

A local farmer who is dropping off a few hides.

He shows a big amount of pallets with already sorted hides, which before heading into tanning will be cut into one shoulder piece, two bends and belly pieces. Here they mainly have the highest weight class of hides of 40 kilos and up, since thick soles is what’s most sought after by their customers.
– Thickness has gone down in the past 20-30 years, and the structure is different, since the animals eat more and grow faster. They don’t get time to grow like they should, in general, so it’s more challenging for us to access the type of hides we want to have, says Thomas.
If there’s something one can find here at Martin, it’s knowledge on history and traditions. And even if this is a place where they do things the old way in many regards, also here a lot has changed, since demand has changed through the years.

Raw hides from local tanneries placed in a pile with salt, soon to be cut into shoulders, bends and bellies and sorted.

Pallets with already sorted hides sourced from Austria.

Gerberei Martin was founded by Georg Martin, born in 1620 and passed away 1699. Through the centuries, the tannery has switched location four times, but always located in Tuttlingen. First it was more central in the village, but as the town grew it became unpractical. The current location they moved to in 1972. It’s a convenient location with both the small river and a spring, where they can get water from.
As in many parts of Europe, and other parts of the world for that matter, the shoe and tanning industry was way different back in the days. In Tuttlingen alone, today a town with 35,000 inhabitants, there were 26 tanneries and 42 shoe manufacturers before the World War I. Nowadays there’s two tanneries left (which is more than in most places) and no shoe factories. The decline in tanning and shoemaking in Germany started after WWI, and after WWII it went downhill even quicker. Looking at oak bark sole leather tanneries, as many know now J. Rendenbach is closing, so left is basically Martin and two other small tanneries, but both of those mainly focus on other things than soles nowadays.

In a room further in from where they store the raw hides, the first two drums of the tannery is found. In these drums they first clean the hides in water for 24 hours, then they add lime (chalk) and hydrogen sulphite and it goes for two more days. The latter is the only chemical used when doing oak bark tanning.
– It’s the same for all tanneries that do fully vegetable tanned products, one still needs to use a chemical for dehairing. Some state they do it only mechanically but it’s not the case, one do need some chemical, Thomas Martin says.
– Only other option to really have all hair come loose properly is to do it like they did back in the days, where they hung the hides in a fully closed room, so the hides start to rot, and after a few days at the exact right time one would bring them out and mechanically dehair them. But if you take them too early hair don’t come off, and too late the hides are damaged and will look really bad, plus usually it differs between hides so the spill would always be large. It’s just not realistic to do it that way.
So what do you say to those who feel that chemicals are problematic?
– That as long as it’s handled correctly, which all European tanneries do because of very strict regulations, it’s no problem. We have closed systems where all water have to be cleaned, and filtered air. It doesn’t harm the environment at all, if done the right way.

After two days in the drum for dehairing it’s another 24 hours with only lime. Then it’s off to a fleshing machine which removes all the remaining flesh from the hides. This flesh is sold to a company in the city where it becomes biogas. It’s the same with all remains that isn’t used here, like the bellies for example, it’s sold to China where it’s tanned and made into smaller, cheaper leather goods. All is used in some way, and as most knows, skins are already a bi-product from the meat industry.
For sole leather, one only use the neck / shoulder – which can be made into insoles or heel and toe stiffeners – and the bends which is the back of the animal with each side becoming one bend – this mainly becomes outsoles and heel lifts. Shoulders are thinner and a bit less dense, bends are thicker, have a tighter fibre structure and harder grain.

One of two drums where the hides are cleaned and dehaired.

The fleshing machine, which grinds off the last of the flesh from the now hair free bends and shoulders.

The flesh removed will be used for biogas.

After dehairing, the actual tanning starts, this in the so-called first tanning, or pre-tanning. Here the pits are hanged and put into large water filled pits, where the first ones contains very little tanning agents, and then each day they are moved to the next pit which is stronger, until they reach the fifth one which is rather strong. I actually got to taste the difference between the water in the first and last one, dipping a finger and tasting it, where the first one almost tasted a bit sweet, but the last one really strong and astringent.
– If one would immediately put the hides in the long-term pits, the hides would be shocked and it would sort of close-up and not be able to absorb the tanning agents. Therefore, one needs the pre-tanning to get the hides used to the process slowly and have them open its fibres, says Thomas.
He cuts a hide in one of the middle pits and shows how it has started to become tanned on the flesh and grain sides, but most in the middle is still untanned.
– Here in these pre-tanning pits we use extracts from valonia oak fruit, an oak tree family that grows in Turkey and Greece, chestnut bark from Slovenia, and mimosa from Italy.

Thomas brings up a section from the pre-tanning pits. Before they built the new first tanning area in the tannery, they had to do this by manpower, now they have a more convenient small crane device.

Shoulders, which just have started the tanning process.

On the cut piece you can see how the skin has started to become tanned in both ends, but most of the middle is still raw.

The hides are in constant movement here, slowly swinging back and forth, to make sure that the tanning agents reach everywhere so the whole skins are tanned evenly. In the pits in the back end the hides start, there the water contains very little tanning agents, then they are moved step by step up towards where I stand with the camera.

The use of extracts in the first tanning is the main difference in how Gerberei Martin do things today, compared to how it was done here historically. Up until the middle of the 1900’s, one only used bark, also in the first tanning stage. In Germany, after World War I when, as mentioned above, some tanneries started using synthetic and chemical ingredients in the tanning, a German sole leather association was formed to preserve the quality and traditional ways of doing things. At the peak sometime before WWII, there were 185 tanneries in Germany that were part of the association, and then there were about the same number of sole leather tanneries in the country which weren’t part. The association had strict rules on how the processes should be made, and all member tanneries had to follow this. Apart from having to stay in the final long-term pits for at least 24 months, one was for example not allowed to use any synthetics or chemicals, no extracts only real bark, and one was not allowed to bleach the leather. However, since around the 1950’s, basically no tannery has followed these rules fully, and the association sort of dissolved.

So, why not do things like they did back then? Thomas Martin explains:
– There’s two reasons. First, what customers want has changed. If one would do it the old way, the leather would have lots of visible scars and defects, there would be big colour differences, and so on. Back then, customers didn’t care about this, durability mattered much more. Regular people worked three months to be able to afford a pair of shoes. One didn’t care about looks, it should last. But it’s totally different now, the look has to be clean, smooth and uniform – people judge quality much more with their eyes today, and in most cases a pair of shoes isn’t an investment as it was back then. And we need to offer the things that people want.
– Secondly, if done fully traditionally, it would be much more complicated. I’ve already mentioned how complicated dehairing was. If only bark would be used in the first tanning, it would mean lots of more work. To have the tanning process set in motion one have to have 40% of tanning agents, and German oak bark only holds around 11% of tanning agents. To get as much bark as would be needed would be very hard today. Also one would have to replace everything in the pits three-four times during the whole pre-tanning process just to get enough amounts of tanning agents.
Was the sole leather better when done the way they did it back then, following the association rules?
– Yes, if one look at durability. And sure, the way we do it now is a bit more lazy. But it’s the only realistic one today, and we have to do it the way we do now to sell our products. We strive for the best quality possible, but we are a business, we also have to align with what our customers want.

Extract is basically like aroma in food, it’s still just bark, but it’s concentrated. One pour bark and water into a drum and mix it to bring out all the the tanning agents, which is then taken out in concentrated form. However, when done the way they do it here at the Martin tannery, where they stay for a long time in the long-term pits with only bark, one can be rather soft in the pre-tanning and don’t add substances which will have the fibres remain open, and one can use solely bark in the final pits instead of mixing in extracts also there.
After pre-tanning the hides goes into a gigantic drum, also this with extracts, where the second tanning takes place. Here they stay for a couple of days, where the drum moves every 30 minutes, just to have the hides change place inside. It’s still to make sure the tanning agents reach everywhere. When taken out of here, the hides are tanned to about 1/3 from the flesh side, 1/3 from the grain side, yet the middle is still untanned. This will be finished in the next, biggest step of the tanning process.

The massive drum for the second tanning stage.

The bends on this pallet have finished the second tanning, and are waiting to be placed in one of the long-term pits where the main tanning process takes place.

They are sort of tanned 2/3 of the way through, but the middle won’t be reached properly with tanning agents until later in the large pits. The hides are fully ready to be taking in the gentle tanning agents from the bark in these.

We head into the largest room of the tannery, where they have their gold mine of huge pits full of hides. The main tanning pits, where each pit holds around 1,200 hides. They are laid in layers with German oak bark and a bit of valonia oak fruits in between, and then filled with water. There it stays for at least 24 months. Without stress the fibres in the hides can transform thanks to the slow tanning agents from the bark.
– I don’t know any tannery witch is tanning longer than us. The benefits of doing things this slow, is that the leather becomes extremely water resistant and durable. That’s also what we hear from customers who have tried all the big brands of quality sole leather, that no one beats our soles in terms of durability, says Thomas Martin.
Regarding which bark to use, most bark would result in tanning, but they have different preferences and tanneries use different bark to achieve slightly different things.

When I look around the pits a quick calculation gives at least 30,000 hides laying here. They have a book that gathers info about what’s inside each pit, which type of hides from where, when it was put in and so on. Thomas tells me that they actually have one pit which has hides that’s been there for 12 years.
– Yeah, the hides there is of a thickness and size that’s not really sought after at the time, so we let it be there until it becomes popular again, Thomas says with a smile.
One pit is always opened, and from this they pick up hides several times a week which then goes up to drying and the finishing processes. As soon as a pit is empty, it’s filled with new hides that comes from the second tanning. When I visit a bunch of pallets stand ready to be put in, since the currently opened pit is soon empty, so this will be filled with new hides at the same time as another pit will be opened and be the source for the tannery’s bends and shoulders the coming period.

The main room where the long-term tanning takes place.

After a pit has been emptied with hides, it’s cleaned and made ready for a new round.

Here’s an image taken of when hides are being placed inside a pit, with oak bark and some grinded valonia fruits in between. Photo: Gerberei Martin

After a pit is filled with around 1,200 hides, some wooden planks and large rocks are placed on top to keep them down in the water. Then they lay there for at least two years.

We take a break from going through the tanning process and head out towards the back parts of the tannery premises. In an old barn building they store all the oak bark used in the final pits, and there sure is plenty of it. A huge pile with both bags and loose bark fills half of the building. In the pile Thomas’ kids have placed a steel sheet which they use as a slider when playing around in here. Up through an extremely narrow stair the oldest machine of the tannery is found. It’s from 1825, and is used to grind the valonia fruits before going into the final pits. Back in the days it was powered by steam, now it’s powered by electricity.
Next to the barn there’s a number of outside pits, which they use a bit during summer when they sometimes move things around a bit or start early for some hides which are to be moved in to the final long-term stay later on.

Combined storage of oak bark and kids playground.

German oak bark.

Turkish valonia fruits.

The oldest machine of the tannery, from 1825, where valonia fruits are grinded.

Some extra pits outside.

The hides that are brought up from the large pits after 24 months plus, are placed in a new drum where they are cleaned and excessive tanning agents are washed away. Then over to another drum where they are bleached, to get the light brown, uniform final colour that we like so much and expect of sole leather today. Then hides are going through a semming machine which press out water, and a setting machine which stretches out wrinkles.
After this, up to the drying room on the third floor of the factory. This is my favourite place of the tannery, the smell is lovely, and the long rows of hanging bends and shoulders are a beauty to behold, where the sides of the room are open so air circulate all year around. During summer they dry rather quick, in around four days, in winter it’s maybe two weeks and they also need to heat the place.
– After a first drying hanging, when the right moisture gradient is reached, they are pressed to stay flat, and then up hanging again. When dry they are placed on pallets waiting to go down to the finishing room.

Cleaning drum.

Wet hides after cleaning and bleaching, they will soon be through the semming machine and setting machine.

Hides hanging to dry in the drying room in the attic of the factory.

Half-way through drying or so each bend and shoulder is pressed to retain a flat shape.

Hides that have been dried, and are waiting to be brought down to the finishing room.

A bend, which is one side of the cow, from the shoulder and back.

Here, on the second floor, is where the hides are transformed into either finished bends and shoulders, or punched out to full soles, half soles and top heel lifts in the case of bends, and stiffeners and insoles in the case of shoulders. Of the bends Martin produce 20% are delivered as full sides, the rest is punched to final soles and lifts. They use all of the bends, but some of the shoulders, those that aren’t of the ideal thickness etc, are sold to Italy where they make leather goods of them. The scrap pieces after punching and cutting are sold to producers of bonded leather.
I’m here late a Saturday, yet when we enter the finishing room Manfred Martin, Thomas’ father, stands working next to a machine in the far end of the room.
– We live right next doors, and we work pretty much all the time. It’s me and my father who do it all, only with the help from some extra staff occasionally when there’s extra much work. We’re not a big operation for sure, says Thomas.
73 year old Manfred explains that he has done this his whole life, it’s all he knows, but he knows it well.
– I could run this place in my sleep, if I turn blind it wouldn’t matter, he says and smiles.
– You can retire in ten years or so, then it’s okay, says Thomas and pats his fathers back.
Thomas has indeed been working in other places, yet…*drumroll*…only at other tanneries. First half a year in Italy to see how they did things there and to learn Italian, which is important since they source stuff from and sell a lot to Italians. Then at a now closed tannery in Germany, before coming back home to work with his father.

In the finishing room, they first sand the flesh side so it becomes more smooth and even. On thick bends they have to do it a few times, and maybe 300-400 grams are sanded away. After this they de-dust the leather, so it’s clean and neat. Then, it’s time for a very important step for the final product, the cylindrical machine, which is a huge roll that compress the hides. In general, due to the long tanning in the pits, the leather from Martin is relatively stiff. But they can do a lot to change the properties, if the customer is after something more flexible they choose pliable bends, press them rather loosely and do some other parts to keep them softer. For harder soles, the cylindrical machines goes on the bends tougher with more pressure, compressing the fibres thoroughly. And so on.
– Our main customers are cobblers and wholesalers of shoe repair products, plus the orthopaedics industry, Thomas says.
– We sell some to shoe manufacturers, and some to bespoke shoemakers. But to be frank, we don’t want too many customers that are too big, and we don’t want too many bespoke makers.
Okay, that’s interesting. Why not big customers?
– Cause if one would have to close or decides to stop working with us for some reason, it would be a big hit and we would have a lot to cover. If a bit smaller, and they go bust, it’s of course sad and not something we wish, but business-wise it doesn’t hurt us that much. Plus if we were to have many large customers we wouldn’t be able to supply them without starting to take shortcuts to speed up the processes, and we don’t want that.
Makes sense, so why not small ones like bespoke shoemakers?
– Well, as I mentioned, we do supply a few, and even if we don’t do that much insoles we can make it and do it upon request. We love what bespoke shoemakers do, and how they work. But the problem from our point of view is that bespoke shoemakers have so many different preferences. If you take ten bespoke makers, you have ten different wishes of specifications on the products. We are impressed with a tannery like Garat in France who can offer a lot of flexibility. But for us, it’s easier to find a middle way that works for many cobblers, same thing with orthopaedics.

The finishing room.

The machine that sands the flesh side even.

The cylindrical machine which compress the leather. The settings and how this is done have a great impact on the final product features in terms of denseness and flexibility.

Templates at the mechanical machine.

The newest machine (and the ones that causes most troubles) is this computerised cutting machine.

Bends turned into sole shapes.

The scrap will be sold to producers of bonded leather, which is where one sand it to leather dust and mix it with glue and press new plates covered with synthetics, which still can be called “leather”.

What one also have to mention is the very old-school way that Gerberei Martin work with their customers. You might have noticed that there has been no link to a website, which I otherwise always have for companies I write about. Well, Gerberei Martin don’t have a website.
– We know there is a basic one out there, but it’s not ours, we don’t know who have made it, Thomas says and laughs.
I don’t bother asking about Instagram or other social media. After all, this is a company where they still have a fax number on their business cards. What Thomas and Manfred Martin do is to visit their customers personally, like one did in the old days. 400-450 customers – two times a year.
– There’s no problem to travel during periods, the pits are still there doing their thing on the hides. On a good day I can squeeze in 20 customers, Thomas says.
This old-school approach is likely why relatively few, outside those working in the shoe repair world, have heard of Gerberei Martin, even if their products are found in a lot of places around Europe, and also in the US and Asian countries like Japan. Thomas shows me some of all the different stamps they have. Three are their own, and then they sell a lot of soles branded for various wholesalers of shoe repair products and similar.
– For us, we have no problems finding new customers. It’s a small trade, people hear from others about us, and also most of our customers are with us for a long time.

Shoulders with the stamp of one of their customers in orthopaedics, which is made to be rather flexible.

The three different stamps that are Gerberei Martin’s own. The middle one is inspired by the triangular stamp that was used for the old German sole leather association’s members’ products which was a guarantee that all the rules had been followed (this was in some cases used also much later by companies not following these guidelines, which was seen as highly problematic).

A bunch of different stamps, some that still are in use, some who aren’t used anymore.

We talk a bit about the fact that the most famous sole leather tannery in the world, J. Rendenbach located further up in Germany, is about to close down its business.
– It’s of course a sad thing. I mean, sure, we probably will gain some new customers from it, but in the long run knowledge about this industry disappears, demand for equipment etc. used in our industry decline, and so on, which isn’t good for us or anyone else. And you never see new tanneries open here in Europe, if one closes no one new comes along.
The fact that Gerberei Martin is the most traditional full scale oak bark sole leather tannery around, is likely something they benefit from in the long run, Thomas thinks.
– Most tanneries who do so-called oak bark tanning or similar one with chestnut do it quicker than us, in around six months in general. They prep the leathers more in the pre-tanning so they are open to absorb tanning agents quicker, and they have the hides in the long-term pits for only six months or so, which means that they would have to use some extracts here as well, otherwise with only bark it can’t really be done in less than a year. For those who test our soles and compare them to these, one notice the difference, says Thomas.
– Then we respect that our products aren’t for everyone. And I think this quicker oak bark tanning still is better than what is done in for example Italy, where the process is speeded up even further in different ways, and sole leathers are finished in just 2-3 months. We don’t want to do it that way. And for us, at least this far, things seems to work well for us. Hopefully we’ll be around for another 400 years.

As mentioned, Gerberei Martin don’t have their own website, but can be contacted on this e-mail address: gerber@gmx.li.

Finished products waiting to be packed and sent out to waiting customers.

This is not soles for big foot, in Switzerland they use leather between horses feet and the iron horse shoe shoe, so that’s what these are for.

The Martin family tree, from Georg who founded of Gerberei Martin in 1645, up to Thomas today.

This is a hide that was found when they built a bridge in Black Forest, where old pits from a tannery that closed during WWII was discovered, containing a bunch of bends. The hides had been in there for almost 70 years. Gerberei Martin finished the hides and turned them into outsoles, hard and extremely waterproof and extremely durable. Here one can see how soles that were tanned only with oak bark, without extracts at all and which were not allowed to be bleached would look. Perhaps not fully as dark as these, but otherwise very similar.

They are uneven in colour, with lots of marks and blemishes visible. To sell leather soles looking like this would not be possible today, no matter how superior the wearing qualities would be. The visual quality triumphs, at least to a certain degree.

Flesh side of this old hide.

Here one can see how this leather looks when bleached. More even, but still not acceptable for most customers.

Finished goods, this is for a customer nearby who will come pick them up himself.