This article details the world of industrial tanning, covering the history of leather, different methods of tanning, and the process that leather goes through in a tannery. We'll start with the basics. It makes sense to begin by identifying what "tanning" is. Tanning refers to a series of chemical processes that turn raw hides into leather. This complex process involves several key steps, which we will detail later. Hence, a tannery is a kind of factory or workshop where the whole process is done. As you may have guessed, leather artisans were historically known as "tanners." That's enough tanning terminology these days. The historical importance of the tannery cannot be overstated. They have been important to human communities for thousands of years, extending well beyond the Middle Ages into ancient times. 
Leather has always been an indispensable tool in the development of human civilization, providing clothing, footwear, and shelter. We must thank the tanners' ingenuity for delivering this excellent material. China dominates the modern leather tanning industry, accounting for 25% of global production (BizVibe). This is mainly due to its large livestock industry and its position as the world's leading manufacturer and exporter of footwear. Russia and Brazil are the next two largest leather producers, followed by India in fourth place, with growth driven by strong domestic demand from a growing middle class. It is difficult to determine who invented the tan. This activity may have begun to gain ground around 10,000 BC when our nomadic ancestors first engaged in herding. For the first time in history, there is a steady supply of hides that can be turned into leather in its original form. These early operations were relatively small and simple by modern standards. 
Tanneries began to appear in Sumer (Iraq and Kuwait) and Melgar (Pakistan) around 3000 BC. The Sumerians were known for their practice of vegetable tanning: a method that involved soaking raw hides in vats containing a concentrated solution of tannins (tannins are natural compounds found in trees, bark, and fruit). However, the ancients used several methods, including alum (mineral) and oil tanning, based on rubbing the leather with animal brains. Although there are different tanning techniques, all tanners perform the first steps of waxing and then softening (softening) the leather. Until the Middle Ages - when the depilatory power of quicklime was discovered - these steps required soaking the raw hides in urine and treating them with feces. The tannery was associated with smell and relegated to the outskirts of town. This resulted in the lower social status of tanners. During the Middle Ages, advances in technology, the expansion of international trade, and the early flourishing of capitalism contributed to a huge increase in the demand for leather goods, which benefited tanneries. Wealthy European elites enjoyed making intricate leather interiors and elaborate leather footwear, while farmers brought rawhide belts to local medieval tanneries to make durable clothing. 
Industrial leather tanning
In 1858, when chrome tanning was invented, the basic process of tanning leather changed completely and was made industrial. Rather than using natural vegetable tannins, this method relies on a solution of chemicals, acids, and salts (particularly chromium sulfate) to convert hides into leather. The surgery normally takes up to four months and is reduced to just one day. Chrome tanning helped meet the surge in demand for leather products during the Industrial Revolution – particularly belts used to operate military machinery and equipment – and now accounts for 90% of global leather production. The modern tanning process is complex and involves several steps. We'll keep things digestible by only touching the key milestones. Before you begin, it's important to remember that the exact process will vary depending on the nature of the tannery, the type of animal hide, and the desired outcome of the leather (e.g., suede vs. full grain). The first step for tanneries is to source hides. In the EU, hides, and skins must be obtained as a by-product of the meat and dairy industries, but this is not always the case in less economically developed countries (LEDC). As soon as the tannery receives the skin, it is treated to prevent it from biodegrading. 
Let's move on to the so-called "beam house" operation, the stage preceding the tanning. Dried hides should be soaked in fresh water to remove salt and re-moistened for further processing. Next comes the lime. In the early history of leather tanning, this was done by soaking the leather in urine. But now, they are placed in a lime (calcium hydroxide) solution to remove excess hair and flesh. Depending on the desired finish, the hides are then softened, which involves treating them with enzymes to promote softness and suppleness. Splitting is generally considered the last stage of pre-tanning. This involves mechanically cutting the leather into two layers. The top layer, or "grain," represents the strongest and most desirable part and will be used to create luxurious full-grain leathers. The underside will remain split or suede. At this point, the leather is ready for tanning. What happens next depends on the method chosen. Chrome tanning is automated and can be completed within 24 hours. It consists of placing the skins in a bath containing acid salts. 
The skins quickly absorb the chromium agent and are then transferred to a tub of decreasing acidity until the process is complete. The wet chrome tanned leather that emerges is known as "wet blue" due to its distinctive blue appearance. The alternative, responsible for 10% of the world's leather, is vegetable tanning: a traditional technique in which hides are placed in buckets filled with a solution of water and natural tanning agents. Over about a month, the skins are slowly spun in different barrels with increasing concentrations of tannins. Essentially, the post-tanning stage contains all of the additional chemical treatments used to improve the physical appearance of the leather. The leather is refined for commercial use. After drying, oil and wax are applied to aid lubrication, making the leather stronger and less likely to crack. A combination of stretching, cutting, and measuring with a gauge can achieve the desired thickness and size. Thicker varieties can be used to make heavy machine belts, while thinner leathers are great for everyday accessories like wallets. From there, sheen, color, and texture can all be carefully modified to suit the retailer's needs. Applying dye produces leather in various colors, "set" removes creases, and polishing has a polished, shiny finish. The possibilities are many, which is why tanneries often specialize in specific types of leather. 
Leather tanning process
As mentioned, most hides used for tanning in the western world are animal skins and a by-product of the global meat and dairy industry (our tanneries endorse this practice). The leather industry plays a vital role in a circular economy, reusing raw materials that would otherwise end up in landfills. Landfills are already major sources of harmful greenhouse gases such as methane (CH4) and carbon dioxide (CO2); further dumping hides and skins will only exacerbate the problem. In this case, farmers will also be forced to bear the financial burden of the landfill levy for hides (€120 per tonne, rising in the UK). For now, there is no better alternative to using discarded hides and skins than making leather. Enter the leather tanning process. An accusation often against the leather industry is that when mismanaged in developing countries, it produces chemical by-products that damage local ecosystems, from farmlands to rivers. It is a chrome tanning product that treats hides with chrome and lead salts. Another problem with chrome-tanned leather is that it does not biodegrade, leading to the discharge problem mentioned above. 
In contrast, vegetable-tanned leather is treated with natural and organic tannins and biodegrades over time. No toxic chemicals or carcinogen is required in the tanning process, making it safer for employees and the environment. Although it is a more environmentally friendly method, a disadvantage of vegetable tanning is that it requires a lot of water. In economically developed countries (EDCs), tanneries are now highly industrialized and sterile, using advanced technology to control all aspects of the tanning process. While in the past, the role of tanner was seen as a physically demanding job, heavy machinery now takes up most of the "heavy" work. Modern laborers are skilled and trained by apprentices – a tradition that dates back to medieval craft guilds. In western countries, leather tanning is a highly regulated industry. For example, tanneries in EU member states are subject to strict regulations relating to using chemicals, animal by-products, and the environment in the workplace. The same does not hold true for other regions. While the leather industry in Southeast Asia, particularly in countries like Bangladesh and India, has spurred employment and economic growth, the laws are vague and poorly enforced. 
Unskilled workers often face unsafe working conditions, and the industry is responsible for harmful environmental behavior (Human Rights Watch). The future presents several related challenges for modern tanneries. Prices for raw materials, including hides, have fluctuated recently as global supply chains have collapsed. At the same time, the push for carbon neutrality and recent discussions on carbon taxes mean that tanneries must continue to reduce water and energy consumption levels and keep pace with the global sustainability agenda. True to tradition, family-run tanneries continue to draw inspiration from the past by finishing all leathers by hand. The result is a high-quality, natural, and extremely durable material that forms the cornerstone of our entire collection, from stylish briefcases to practical wallets. Artigiano del Cuoio's sustainable manufacturing approach includes controlling the entire production process, avoiding the use of hazardous chemicals, and optimizing resources to reduce water waste. 
We are proud to partner with a tannery committed to tackling the negative environmental impact of leather production. The tannery is a long-established institution that has been important in almost all societies since the 3rd century BC. The demand for leather goods is expected to increase in the 2020s, and tanneries will continue to play a key role in global manufacturing.
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