Production and Development Process of Vegetable-Tanned Leather

What is Vegetable-Tanned Leather?

Vegetable tanning is a method used to process raw hides. Raw hides are taken from animals and are referred to as "green hides" or "unfinished hides." Without treatment, raw hides will rot, but after being processed, they become leather. Vegetable tanning refers to the tanning process that uses plant-based materials to preserve and maintain the flexibility of the leather. "Vegetable tanning" refers to a method of tanning rather than a specific type of leather, and it can be applied to various types of hides such as cowhide, sheepskin, and others. The tanning agents used are plant tannins, which are poly phenolic compounds (tannins) found in plants. Plant tanning materials include tree bark, leaves, fruits, and other plant parts rich in tannins. Vegetable-tanned leather has strong water absorption, high malleability, and is ideal for carving and molding, typically finished with a polishing technique. However, due to the compact fiber structure of the leather, it has limited stretch and poorer flexibility.

Vegetable-tanned leather is typically in its natural color, with minimal coating, allowing the pores to be clearly visible on the surface. This is why it is more susceptible to water absorption. One characteristic of vegetable-tanned leather is that it changes color when water is dropped on it. The color change is more noticeable on lighter or white leathers—water quickly penetrates the surface, and the leather turns reddish. After the water dries, the color deepens. Over time, the leather naturally oxidizes and gradually turns a warm brownish-yellow. With continued use, the color stabilizes, and proper care enhances the leather's natural shine, giving it a desirable "old beeswax" color.

The color change is a natural oxidation process where the leather absorbs water and is exposed to air. All leather will eventually change color, but it is less noticeable in darker or colored leather. This characteristic is particularly prominent in vegetable-tanned leather, which is why many leather workers wear gloves to prevent uneven color development. Over time, as the leather accumulates oils, sweat, and natural oxidation from handling, the leather becomes brownish-yellow or reddish-brown. As the leather ages, it develops a unique patina that reflects the passage of time, making it a beloved feature of vegetable-tanned leather.

The Production Process of Vegetable-Tanned Leather

The production process of vegetable-tanned leather is a complex and skillful one, often taking weeks or even months to complete. Compared to chrome-tanned leather, vegetable-tanned leather uses natural plant extracts (like tannic acid) in the tanning process, making it more environmentally friendly and allowing it to develop unique patina effects over time.

1. Preparing the Leather The first step in producing vegetable-tanned leather is preparing the raw hides. These are usually cowhide, sheepskin, or pigskin, which undergo cleaning and dehairing to become "green hides." At this stage, the leather is stiff and has a strong animal smell and must go through dehairing and cleaning processes.

   Main Steps:

   • Dehairing and Cleaning: The raw hides are treated with lime and other chemicals to remove hair, and then thoroughly cleaned to remove fat and impurities.
   • Dehydration: After dehairing, the leather is treated with salt or other dehydration methods to remove moisture.

2. Tanning Process The core of vegetable tanning is the use of plant-based tannins (also known as tannic acid). The leather is soaked in solutions containing plant extracts, which alter the chemical structure of the leather, making it durable and resistant to decay.

   Main Steps:

   • Tannin Soaking: Leather is immersed in tannic acid solutions extracted from tree bark, wood, leaves, etc. This process may last anywhere from a few days to several weeks, depending on the leather's thickness and the concentration of tannins used. Common sources of tannins include oak bark, chestnut bark, and quebracho.
   • Soaking Stage: The leather is repeatedly soaked in different concentrations of tannin solutions, allowing tannins to gradually penetrate every layer of the leather.
   • Time and Temperature Control: It is crucial to control the time and temperature during the tanning process. Poor handling may cause the leather to become brittle or degrade in quality.
   • Kneading and Pressing: Leather is kneaded or pressed during the tanning process to ensure an even penetration of tannins and better shaping.

3. Drying and Softening After tanning, the leather is dried and further softened. Drying is typically done naturally, and this process helps retain the leather’s natural texture and color. During the drying process, the leather is also kneaded to make it more supple and flexible.

   Main Steps:

   • Natural Drying: The leather is dried in a shaded, ventilated area, avoiding direct sunlight, which could make the leather brittle.
   • Kneading and Stretching: During drying, artisans knead or stretch the leather to increase its softness and flexibility.

4. Dyeing and Coloring Dyeing is an important step in vegetable-tanned leather production. While vegetable-tanned leather typically ranges from golden to dark brown, many tanners use natural or chemical dyes to color the leather. Plant dyes are more traditional and environmentally friendly.

   Main Steps:

   • Plant Dyes: Some traditional vegetable tanners use natural plant-based dyes, such as indigo, hibiscus, and walnut husks.
   • Dyeing and Coloring: The dye is evenly applied to the leather’s surface, and the color is fixed through heating or natural drying.

5. Polishing and Finishing Once dyeing is complete, the leather enters the final finishing stage. This stage is meant to remove excess material and refine the surface, giving the leather a smooth, natural shine.

   Main Steps:

   • Sanding and Polishing: Artisans use tools or sandpaper to gently smooth the leather surface, enhancing its natural shine.
   • Edge Finishing: The edges of the leather are usually refined to prevent them from fraying or peeling, giving the leather a more polished look.

6. Shaping the Final Product After completing the previous steps, the leather enters the final shaping stage, where it is further processed to meet the client’s needs or design specifications. The leather can be shaped into various products like bags, belts, shoes, or accessories.

   Main Steps:

   • Shaping and Cutting: Leather is cut into the required shape and size according to the final product design.
   • Sewing and Assembly: Some leather goods require hand or machine stitching to complete the product.

7. Final Treatment and Quality Control After all production steps are completed, the leather undergoes a final quality inspection to ensure there are no defects and that it meets the required standards. If necessary, artisans perform final treatments, such as applying oil, reinforcing, or adding waterproof coatings.

   Final Steps:

   • Oiling: Some leathers are treated with natural oils (such as olive oil) or wax to enhance the leather’s luster and durability.
   • Waterproofing and Antibacterial Treatment: Some premium leather products undergo additional waterproofing or antibacterial treatments to extend their lifespan.

The Italian Vegetable-Tanned Leather Consortium

The Italian Vegetable-Tanned Leather Consortium was established in 1994, consisting of tanneries, leather goods manufacturers, and designers from the Tuscany region. The consortium grew rapidly, and today it has more than 20 members operating in Tuscany. The area between Pisa and Florence—Tuscany—is renowned for its passion for vegetable-tanned leather and its high production standards. In Tuscany, vegetable-tanned leather is still processed using traditional methods: with time and patience, combining technology and experience, raw hides are transformed into durable leather. Tuscany, known for producing some of Italy’s finest cowhide, has a rich tradition of vegetable-tanning that dates back centuries. With the rise of industrialization and mechanized production, the traditional vegetable-tanning method has been gradually replaced by quicker and cheaper alternatives. To preserve this valuable craft and ensure its global reputation and value, the Italian Vegetable-Tanned Leather Consortium was formed.

Our leather tells our story: who we are, where we come from, what we have done, and how we live. The leather from Tuscany is no different...

The quality of Tuscan vegetable-tanned leather is the result of long-term professional expertise and is closely tied to the lifestyle and culture of the region. The Italian Vegetable-Tanned Leather Consortium acts as the guardian and ambassador of Tuscan leather worldwide. One of its essential tasks is to create quality trademarks and labels. This quality label is a carefully crafted certification with a complex anti-counterfeit system that traces the tannery and manufacturer that supplied the leather.

Features and Advantages of Vegetable-Tanned Leather

Compared to other types of leather, Italian vegetable-tanned leather has several distinctive characteristics:

• Natural and Eco-friendly: Vegetable-tanned leather is primarily tanned using tannic acid from plants, without harmful chemicals, making it more environmentally friendly during production.
• High Quality and Durability: Vegetable-tanned leather is tough and durable, and as it ages, its color and texture naturally change, forming a unique patina that becomes one of its defining features.
• Unique Aesthetic: Due to its natural materials and traditional craftsmanship, vegetable-tanned leather often features unique textures and colors, giving it a personalized, distinct beauty that other types of leather cannot match.

Certification and Labeling

To ensure the quality and traceability of leather, the Italian Vegetable-Tanned

Leather Consortium provides a certification label: Vera Pelle Italiana Conciata al Vegetale. Only tanneries and manufacturers that sign licensing contracts with the consortium can use this label. The label certifies the origin of the leather, the tanning process, and the natural properties of the leather. The label includes anti-counterfeit technology and is recorded for traceability. It is available in multiple languages: Italian, French, English, Japanese, Korean, and Russian. To attach the label to finished leather goods, the consortium recommends using irreversible locks with natural cotton threads.

The Italian Vegetable-Tanned Leather Consortium is more than just an industry organization; it is a protector and promoter of traditional Italian leather craftsmanship. Through strict quality standards and an eco-friendly approach, the consortium helps maintain the uniqueness and high quality of Italian leather craftsmanship, promoting the use and development of vegetable-tanned leather globally. For consumers, choosing leather goods with the Vera Pelle Italiana Conciata al Vegetale label means selecting high-quality, eco-friendly leather products with cultural value.

The production of vegetable-tanned leather is renowned for its natural, eco-friendly, and meticulous processes. Although its production cycle is longer than that of traditional chrome-tanning, its unique aesthetic and eco-friendliness make it increasingly popular with both consumers and designers. Through the use of plant tannins, vegetable-tanned leather is not only durable and unique in color but also develops a distinctive patina over time, becoming a material with historical and emotional value.