Nobody Makes Leather Like This Anymore!

[00:00:00]For generations, leather was one of the world's most essential materials. Yet, turning a raw cattlehide into durable leather took weeks of skilled labor and more than a dozen carefully timed steps.

[00:00:13]In today's age, Skills History episode, we visit the Gabriel Brema Tannery in Germany, where craftsmen demonstrate the traditional process on original machines from the 1900s. From freshly delivered hides to finished leather, follow the five-week transformation behind a process that has almost completely disappeared.

[00:00:34]The Tanner and his assistants begin by inspecting the cattle hides that have just arrived.

[00:00:48]Before weighing them, one of the assistants removes the salt that was applied at the rendering plant.

[00:01:04]A wooden tag on the tail end carries a number under which the hide is logged in the account books along with its weight and color.

[00:01:17]The cler also notes any defects, cuts or tears that would lower the sale price.

[00:01:41]The master Tanner typically bought his hides at auction in nearby Doober.

[00:02:01]He favored hides from southern Germany since cattle there have thicker hides than those raised along the lower rine.

[00:02:19]Every flesh side has to be rubbed thoroughly and carefully with salt. The salt draws out moisture and prevents rot so the hide can be stored for longer without damage.

[00:02:48]Before the hides are treated with water and chemicals, the tanner marks each one with a permanent identifier. Since hides arrive in batches of 50, he uses punch irons numbered 1 through 9 to stamp each piece.

[00:03:21]to record the weight. He scratches an abbreviation into the hide with his knife.

[00:03:52]Before tanning can begin, the salt has to be washed out. A job done in the drum. One of the earliest machines used in tanneries dating back to the 1870s.

[00:04:20]Tanners once washed their hides in flowing stream water and every so often a hide would slip away and get swept downstream. A well-known German expression for something getting away is said to trace back to this trade.

[00:04:38]Today about 10 hides go through a single wash cycle in the drum.

[00:04:50]Adding solvents speeds up the cleaning.

[00:04:53]Traditional soaking used to take up to 2 weeks.

[00:05:06]A wooden paddle wheel driven from overhead beats the salt and dirt out of the hides for about an hour.

[00:05:42]Once cleaned in the drum, the hides are free of salt and dirt, thoroughly soaked and supple again.

[00:06:10]The assistant fishes out any hides that have sunk using a long pole fitted with a Y-shaped iron hook.

[00:06:33]The next steps remove the upper and lower layers of skin, leaving only the dermis, what tanners call the pelt. Only the pelt goes on to be tanned.

[00:07:03]First, the tanner checks that the hides are clean and soft enough. Then, he and a helper load them into the limming wheel above the basin.

[00:07:18]Drive belts turn a large iron ring mounted above the vat.

[00:07:34]The men hanged the hides inside this freely rotating ring.

[00:08:02]This step is called lying since lime traditionally potach was used to loosen the tissue. Originally, tanners soaked their hides in pits dug into the ground.

[00:08:21]These oaklined pits were later replaced by stone basins.

[00:08:31]In the old process, hide sat in the lime pit for up to 3 weeks, and the lime settling at the bottom had to be stirred every 2 days.

[00:08:54]A mixture of sodium sulfide and lime makes the skin cells swell. The lowest layer of the epidermis breaks down and the hair loosens.

[00:09:28]The 3we soak once needed in the lime pits was cut to just a few hours thanks to chemical agents and the mechanical rotation of the lying Deal.

[00:10:00]After about 2 hours, the hides are pulled from the limming solution. They can't stay in any longer or the liquor would attack not just the outer layer but the deeper layers of skin weakening the leather's structure.

[00:10:28]The tanner trims off unusable parts like the edges with a sharp knife and sets them aside with the flesh and fat trimmings collected later in the process.

[00:11:00]The hides, their hair now mostly loosened by the lying solution, are washed again with clear water in the drum.

[00:11:30]For this film, the Tanner demonstrates unhairing by hand with a traditional unhairring knife. He drapes the hide, its hair loosened only by the lime bath over the angled semic-ircular beam and scrapes the hair off against the grain.

[00:11:48]Heat. Heat.

[00:12:21]Tanners used to sell hair and bristles to felt making factories.

[00:12:28]Horse cattle and calf hair went into upholstery or insulation for steam pipes.

[00:12:36]Finer hair from martins, sable or badger was used in brush making.

[00:13:02]Tanneries were usually built near water, which local residents also relied on for fishing, washing laundry, and watering livestock.

[00:13:11]The pollution from soaking hides and dumping spent lime and tanning liquor made disputes with neighbors common.

[00:13:22]The often unbearable smell hanging over the tanneries didn't help the trade's reputation either, though that poor reputation had little to do with the actual skill the craft demanded.

[00:13:40]What's more, the long production time for leather required a great deal of capital.

[00:14:28]Far trickier than unhairing his fleshing.

[00:14:31]removing tissue from the flesh side of the hide, which calls for a razor sharp knife.

[00:15:07]As with unherring, the tanner leans over the beam, working carefully and with a light touch so as not to damage the valuable hide.

[00:15:20]On cattle hides, the head, neck, and hunches tend to be thicker than the rest. To get an even color later, the hide has to be shaved to a uniform thickness without losing too much overall weight.

[00:15:43]Unlike the blunt, curved unhairring knife, the fleshing knife has a straight, sharp blade.

[00:16:01]If tanners didn't clear away the waste quickly and regularly, a foul smell would spread within minutes.

[00:16:26]Scraping off the flesh and fat also stretches the hide at the same time.

[00:16:33]The leftover scraps were once used to make glue since connective tissue's high water content makes it well suited for that. Today, industry uses flesh and fat trimmings in products like cosmetics.

[00:16:47]Heat.

[00:17:05]Heat.

[00:17:18]Once the pelts are fully exposed, the tanners soak them in a stone basin.

[00:17:32]Manual fleshing on Zam continued at this tannery until the mid 1960s when the tanner switched to a fleshing machine.

[00:18:00]The tanner now demonstrates the fleshing machine using hides whose hair was loosened chemically in the limming solution and thoroughly washed. Since before entering the fleshing machine, The hide passes across a fluted roller.

[00:19:00]Shortly after the turn of the century, many tanners had already added unhairring, fleshing, and washing machines to their operations, boosting production significantly.

[00:19:47]The exposed counterrotating rollers of the fleshing machine are controlled by a foot pedal, so the operator's fingers never get caught between them. Workers use tongs to pull the hide through.

[00:20:15]One drawback of the fleshing machine is that its heavy rollers can't adjust to a hide's varying thickness the way a hand tool can.

[00:20:36]Leather aprons protect the workers from moisture and double as a strap for honing knife blades.

[00:20:58]Curved knives and pointed pliers let them quickly trim away edge scraps. Thin frayed edges would only get in the way when the pelts are split horizontally in the next step.

[00:21:10]For splitting, the hides need to be as wet as possible, which reduces the risk of sand or dirt dulling the splitting machine's band knife.

[00:21:35]Once a worker confirms the band knife is sharp enough, the hide can be fed in.

[00:21:40]Running the splitting machine takes five to six helpers.

[00:21:47]Their job is to pull the upper layer of the hide out of the machine as straight and flat as possible.

[00:22:07]An overhead heating fan keeps the room comfortable in winter and stops the wet hides from freezing since frozen hides can't be split.

[00:22:26]Along with the fleshing machine, the splitting machine belongs to the second generation of machinery that entered tanneries after the turn of the century.

[00:22:45]The helpers pull out the grain side, the former hair side, with great care. A moment's inattention and the hide tears, which would mean a significant loss given how expensive cattle hides were.

[00:23:19]At this operation, only the valuable full grain layer, still 0.8 to 1.2 cm thick, went on to be tanned. It was used for sporting goods and orthopedic items like prosthetics.

[00:23:38]The lower quality split layer, often chrome tanned separately, was sent to other factories for further processing.

[00:23:54]Once the hides have been soaked, cleaned, unhaired, fleshed, and split, preparations begin for the actual tanning process. The pelts spend several hours in a rotating drum filled with a baiting and swelling solution. This opens the hides pores so tanning agents can penetrate more effectively afterward. The more the tissue opens up, the faster the tanning that follows.

[00:24:20]Left too long though, the tissue turns spongy and loses its tear resistance. So the master tanner has to gauge the strength of the solution and the timing for each hide.

[00:25:04]Right after swelling, the men load the hides into the ringing machine where counterrotating rollers press out much of the water.

[00:25:28]They make sure the hide feeds through as wrinkle-free as possible.

[00:26:09]At this stage, the hides can't be stored. They'd start rotting immediately and need to be processed right away.

[00:26:28]Now comes the actual tanning, the preservation of the hide. The tanners hang the still white pelts on rods and lower them into the handlers, a series of pits filled with tan liquor of increasing strength.

[00:26:58]After a while, the men move the hides from a weaker handler into a stronger one. Both the makeup of the tanning liquor and the time spent in each pit have to be matched precisely to the type of leather being made.

[00:27:17]The tanning method used here in mowers to produce especially hardwearing leather was one the master craftsman developed himself to ensure even soaking. The tanners periodically turn the rods, shifting where the hide touches the liquor.

[00:27:56]For flawless tanning, every hide needs to hang freely and stay fully submerged.

[00:28:09]The dissolved tanning agents work into the hide's pores in stages, binding around the tissue fibers. This is what preserves the hide, and from this point on, it can rightly be called leather.

[00:28:26]The experienced master judged the right concentration of the tanning liquor by taste.

[00:28:50]Oak bark was always the preferred choice for tanning heavy leather. The dried peeled bark of young oak trees is rich in tanic acid.

[00:29:08]In total, the hides spend 3 weeks in the tanning liquor.

[00:29:21]With the traditional pit tanning method, pelts once took at least a year to tan all the way through.

[00:29:29]Toward the end of the 19th century, as the fiber structure of hide and the effects of various chemicals became better understood, new methods emerged and tanning time dropped to just a few weeks.

[00:29:45]The introduction of rotating tanning drums, which agitate hides in heated chemical liquor, shortened the process further to just 3 or 4 days. Um, today industrial operations can produce leather in under 24 hours using modern mineral chrome tanning methods.

[00:30:18]The tanner in mowers stuck with the lengthy traditional process because it gave the leather a tear resistance that even modern factories couldn't match.

[00:30:41]After the hides come out of the tanning liquor, they go through a 2-hour wash in the baiting drum. While the helper loads the tanned hides in and closes the drum, the master tanner trims off any remaining irregular edges.

[00:31:37]A baiting solution of hydrochloric acid and other chemicals strips out the unbound excess tanning agents from the leather.

[00:31:52]Before chemical baits were available, tanners neutralized the leather with dung. Pigeon droppings were a common choice.

[00:32:08]Looking at this whole chain of steps, it's clear that Tanner's trade demanded not just physical strength, but even by the start of the 20th century, a solid grasp of chemistry and physics, too.

[00:32:49]After the ringer, the men move the leather. To transport the finished pieces, they use a wheeled crate built entirely of oak since any contact with steel or aluminum would immediately stain the sensitive hides.

[00:33:24]Alongside tanning with plant extracts, mineral treatment with alum, known as toing, was also common early on. Unlike the yellowish to reddish brown color of bark tanned leather, torred leather stayed light and whitish.

[00:33:43]For that reason, bark tanners were traditionally called red tanners while those who tooured with alum were known as white tanners or toyers. They produced thin soft leather for gloves and clothing.

[00:34:00]Once the drum is emptied, the process at the mower's tannery calls for the hides to go back into the tanning liquor once more.

[00:34:24]The men lower the leather into the first handler with its weak solution a second time. This after tan is meant to even out the color throughout.

[00:35:09]Before the leather can leave the tannery, the master has to confirm the tanning. agents have penetrated every layer of the skin. Only then is thorough preservation, consistent firmness and durability guaranteed.

[00:35:34]A cross-section reveals whether the desired quality has been reached. If the leather is soft and pliable all the way through, the tanning has succeeded and can be considered done.

[00:36:00]Finally, the leather is mil to make it even more supple. The drum's warm water, enriched with chemicals and beef tallow, softens the leather as it tumbles for several hours.

[00:36:48]Warm water flows continuously through a hollow axle while the spent water is flung out through holes in the end cap.

[00:37:08]This suppleness gained through milling matters especially for orthopedic leather products.

[00:37:31]After about 3 hours, the tanners remove the leather from the milling drum and drape it over a shoulder high beam to drain.

[00:38:09]Good morning.