Although I’ve always understood that leather comes from animals, the logistics of it all confused me. I’ve often been amazed by how an animal’s skin can be turned into one of the most luxurious materials available. I recently decided to look at the tanning process to see how rawhide turns into tanned leather.
Tanned leather is the final product of processing animal hides. The hides can be persevered by utilizing various tannins, preventing bacteria from deteriorating the fibers over time. Three main types of tanned leather include vegetable, chromium, and oil tanned, each with unique qualities.
This article will explore the tanning process, uncovering how an animal’s skin becomes tanned leather.
What Is Tanned Leather?
Tanned leather is the finished product of animal hides being turned into usable materials. After being harvested, the skins of animals are tanned to preserve them. The tanning process uses various combinations of tannins that protect the leather from bacteria or fungi, preventing the leather from deteriorating over time when properly maintained.
Although many tanning processes can create various types of leather, three common types include vegetable, chromium, and oil tanned. These tanning methods play a large role in the final product, providing almost all of the qualities of the finished tanned leather.
What We’ll Explore
- Clearing up Myths & Misconceptions
- History of Tanned Leather
- Tanned Leather Overview Table
- Types of Tanned Leather
- Characteristics of Tanned Leather
- What Chemicals Are Used in Tanned Leather?
- How Is Tanned Leather Made?
- Pros of Tanned Leather
- Cons of Tanned Leather
- Maintaining Tanned Leather
- Alternatives To Tanned Leather
- My Personal Research Into Tanned Leather
- Helpful Tanned Leather Insights
- Key Takeaways
Clearing Up Myths & Misconceptions
A common misinterpretation of tanned leathers is thinking that the tanning method dictates quality. While there is some truth to this, the tanning method does not always reflect the tanning quality. Each tannery will have unique methods for tanning leather, which include quality control and proprietary tanning combinations.
This plays the most significant role in the outcome of tanned leather, as a tannery with lower standards may produce a lower quality overall. This leads to tanning methods often seen as high quality, such as vegetable tanned leather, being unfavorable compared to a higher quality oil or chrome tanned leather.
History of Tanned Leather
In the early Stone Age, raw animal hides were used in various ways, but these hides would begin to rot without treatment. The earliest solution to this issue was to rub fatty substances and meats onto the surface of the leather to help protect it. This method continued to be used until the invention of plant-based tanning.
Another tanning method is said to have been discovered in Egypt and Mesopotamia; people of that time were finely shaving bark off trees to use the natural tannins on the leathers. While this process was much slower than rubbing various fats and oils onto the surface, the leather was much stiffer, expanding the applications of the tanned leather.
In 1856 Friedrich Knapp invented the process of chromium tanning. Using chromium sulfate to preserve the leather was quicker and made the leather softer and more heat resistant. This method of creating tanned leather boomed quickly and has become the most common way of tanning leather due to its cost efficiency.
Tanned Leather Overview Table
|Vegetable Tanned||Processed by using natural tannins found in bark, leaves, and roots. A slow process that creates a firmer leather.|
|Chrome Tanned||Utilizes chromium salts, acids, and chemicals to preserve the leather quickly. A much more efficient method that creates softer leather.|
|Oil Tanned||A chrome tanned leather that may have oils, fats, grease, and wax added to the tanning process. Resulting in a semi-firm, oily, yet more durable tanned leather.|
|Combination Tanned||Combines vegetable and chromium tanning methods to make a hybrid leather, creating a tanned leather that has the benefits of both tanning methods.|
|Suede||Suede can use any tanning method but is most commonly a chrome tanned leather. What makes this tanned leather unique is the fibrous surface that comes from shaving down the hide.|
Types of Tanned Leather
While many types of tanned leather use various tannin combinations, the three main types are:
- Vegetable tanned
- Chromium tanned
- Oil tanned
Vegetable tanned leather is the earliest method used for making leather. This process uses natural tannins such as bark, leaves, and roots.
This combination takes up to two months to fully tan the leather but produces what many consider the best leather.
It is natural, patinas well, and the edges can be burnished easily. Due to the lengthy production process, vegetable tanned leather is often more expensive than others.
Making tanned leather using chromium was invented in 1856 by Friedrich Knapp. The leather can be preserved within a day using a combination of chemicals, acids, and chromium salt. This method of making tanned leather is now the most popular due to its efficiency. Chromium tanning creates a softer and more flexible leather.
Using oil when processing leather is nothing new. In history, fats, oils, and grease would be rubbed on the surface of the leather to help slow the hides from rotting. Today’s method of oil tanning is far different.
Oil tanned leather often uses a chromium tanned process that will then have additional materials added. By stuffing the leather full of waxes, oils, fats, and greases, the leather becomes more durable and water resistant.
Characteristics of Tanned Leather
All tanned leather comes from various animal hides, the most common of which is the cow. Typically, leather is a byproduct of the meat industry, including pigs, sheep, and bison. Taking hides that would have otherwise been wasted. However, several cases of exotic and traditional leathers are not byproducts, potentially harvesting an animal solely for their hides.
The thickness of tanned leather depends on a few things, including the animal, its size, and the age at which it was harvested. Most small or young animals will produce a thin hide when finished.
Best used for delicate goods or to be lined with a heavier material. Large animals will often produce thicker leather, especially if harvested at an older age, meaning tanned leather ranges from 1–18 ounces or .4mm–7.8mm.
Each hide of tanned leather may have varied surface texture depending on the animal, and how it is processed. Tanned leather may have scales, bumps or be completely smooth. At the tanneries, hides may also have texture imprinted on them, artificially recreating the texture of other animals or leather types.
Tanned leather will have varying degrees of water resistance, but none will be waterproof. Fibrous, or natural leather, will have the worst water resistance and quickly soak in any liquid on the surface.
Leather with a heavy finish, including wax, oil, or polyurethane, will have the best resistance. Water will roll off the surface of these leathers. However, if the water is allowed to pool on the surface, it may still penetrate, causing damage.
Most of the color in tanned leather is added during the hide’s processing. While natural vegetable tanned leather will be blonde and darken over time, all other leather types need color added. After the leather has been preserved, they are added to vats with dyes to soak in color, meaning tanned leather can be almost any color.
The cost of any tanned leather can vary greatly by animal, tanning type, and the tanneries themselves. The most common animals, cows, pigs, and lambs, are often cheaper than exotic leathers.
However, the price for them increases during the tanning process. The same cowhide can be treated by two different tanneries and have two different price points. This largely has to do with the final quality of the leather, as a well-established tannery will most likely produce the highest quality product.
The flexibility of tanned leather heavily relies on the tanning method used to produce it. Vegetable tanned leather tends to be much stiffer than chromium tanned. The chemicals in the chromium process break down the leather fibers much more efficiently.
In addition, the animal itself can play a role in the flexibility of the leather it produces. Thick, firm hides will not be as flexible as a younger animal with a softer hide. Claves, lambs, deers, and pigs often offer some of the most flexible tanned leathers when they’re made using the chrome tanning process.
Relative to other crafting fabrics, any tanned leather is extremely durable. Tanned leather is typically thick, with great tensile strength. The surface is often abrasion-resistant and often partially water-resistant.
While most tanned leathers can last for decades, they must be maintained. Dryness and cracking are common concerns as the leather wears over time. However, periodically applying a leather conditioner will keep tanned leather hydrated and free from damage.
The tanning process uses various combinations of tannins that protect the leather from bacteria or fungi, preventing the leather from deteriorating over time when properly maintained.
There are seemingly endless uses for tanned leather. Pieces can be used for utility or as a creative outlet. With various types of tanned leathers offering different properties, there seems to be a leather for any desired use.
What Chemicals Are Used in Tanned Leather?
The first chemicals to come in contact with the animal’s hide during the tanning process are calcium hydroxide and sodium sulfide. This combination helps remove the hairs on the leather and break down the fibers to help soften it.
Sulfuric acid, or formic acid, is the next chemical used. This helps prepare the leather for tanning by reducing the pH level of the hide. A tannin combination is used to preserve the hide during the tanning process. These chemicals bond to the proteins of the leather and protect it from bacteria and fungi and include:
- Trivalent chromium
- Vegetable tannins
How Is Tanned Leather Made?
Any tanned leather begins as animal hides harvested and preserved with salt. They will then be shipped to various tanneries to be made into leather. At a tannery, hides are washed and scraped clean. At this point, the hides are added into vats filled with their unique tanning chemicals.
Vegetable tanned leather will use natural tannins found in bark, roots, and leaves — both chrome and oil tanned use chromium salts to preserve the leather. Oil tan goes a step further by including fats, oils, or waxes into the leather to give it its finish. After tanning, the leather is dyed in a separate vat, adding a finish to the surface. The full grain leather is then ready for shipment to retailers.
In this video provided by Insider Business, we get an informative look at one method of tanning leather. Highlighting the history, as well as the process of vegetable tanned leather.
Pros of Tanned Leather
Tanned leather is a popular material used for hardwearing utility goods and delicate high-end fashion. This material has been used for thousands of years and shows no signs of being replaced anytime soon due to its benefits, including:
Cons of Tanned Leather
Although innovation has occurred in the leather industry over time, concerns with tanned leather still exist. The problems they face have been challenges since the discovery of leather, and currently, they have no simple solutions to address them. These include:
- Harmful to the environment to produce
- Various animals cause ethical concerns
- High-cost material
- Damaged by water
- Must be maintained to prevent damage
O. Tunay, I. Kabdasli, D. Orhon, and G. Cansever, from Istanbul Technical University, Civil Engineering Faculty, in Istanbul, Turkey, discussed the concerns regarding water usage in the tanning process. Their research found that a lack of regulation may lead to wasting large amounts of water and potential contamination with improper disposal of tainted water generated from leather tanneries.
Maintaining Tanned Leather
Each type of tanned leather will have a different maintenance process; however, there are a few universal steps for treating most leathers. Suede, Nubuck, and other fibrous leathers should not have any soap or conditioner applied to them unless it is specifically made for that type of leather. Maintain tanned leather by following these steps:
- Using a horsehair brush, thoroughly pass over the surface to remove dirt and debris.
- Apply a leather soap, after testing on a hidden area, with a clean rag. A small amount of soap is ideal to prevent any damage to the leather.
- Allow the tanned leather to dry.
- Use a different clean cloth with a tested leather conditioner to rehydrate dry leather by completely covering the surface of the leather and wiping any remaining excess off.
Alternatives To Tanned Leather
There may be a few reasons why someone would want to use an alternative to tanned leather, but luckily there are other options. Various vegan alternative leathers use plastic, cactus, mushroom, and other materials to create artificial fabric.
Another great alternative to leather is waxed canvas. While it may not look or feel the same, the durability is comparable. Those looking for a lower-cost yet durable fabric may consider it.
My Personal Research Into Tanned Leather
With tanned leather being a popular material, I wanted to see what people look for when shopping for leather goods. During my research, the majority of consumers that I came across had little to no knowledge of leather. They could often point out a suede tanned leather, but it seemingly ended there. Therefore, I had to take a different approach and focus on the characteristics rather than the type.
The first group of enthusiasts I looked at were those that collected handbags. They often owned many luxury leather pieces and had a good understanding of what they wanted. They seemed to want soft, flexible, and durable leather, avoiding heavy finishes that made the leather feel like plastic.
To my surprise, they express a distaste for leather that would develop a patina, wanting to keep their bags looking as new as possible. Their desires fit perfectly for a chromium tanned leather with a light finish.
The next group I looked at was the bushcraft community. They are known for enjoying high-quality materials and purchasing plenty of leather goods. The bushcraft community seemed the opposite of the handbag enthusiasts. Their desires were for functionality, focusing on long-lasting and wear-resistant leather.
The community itself seemed somewhat split as many wanted a patina, while others preferred lower maintenance. The qualities they describe are either vegetable or oil tanned leathers, as both are highly durable, with oil tanned being more suited for hardwearing conditions.
As a leather crafter who prefers vegetable tanned leather over any other type, I was surprised to see so many prefer chrome or oil tanned leather. Although each community will have its own preferences, the variations in tanned leathers means there is a perfect leather for everyone.
Helpful Tanned Leather Insights
Is tanned leather real leather?
Yes, all leather of any quality is tanned leather. The term “tanned” refers to the preservation of animal skin, referring to the use of tannin, the substance used to process the rawhides into the material known as leather.
What does leather tanned mean?
The ending term “tanned” refers to the tannins used while preserving the leather. This helps quickly identify how the leather has been treated. A vegetable tanned leather has natural tannins, while a chrome tanned leather uses chromium as its tanning agent.
What is the difference between tanned and untanned leather?
Tanned leather is any rawhide that has been processed for preservation and use. While untanned leather has not, it may still be a hide that has yet to be treated. Untanned leather is not a material used in leather goods.
How did they tan leather in the old days?
Many of the techniques used for old-world tanning are still used today. The hides would be cleaned, scraped, and softened before they were prepared for tanning. They would stretch the hides using frames and dip them in vats full of tannin, which had been gathered from tree bark, plant roots, and leaves.
What did Native Americans use to tan leather?
The Native Americans would tan their leathers using fatty animal tissue and grease. After preparing the hide by scraping the leather clean, they rubbed the surface with these ingredients to tan the leather. This process, similar to oil tanning, softens the leather but leaves it oily to the touch.
How did Eskimos tan leather?
The Inuit, the indigenous people of the Arctic, tanned their hides using alder bark. The people would shave down fine pieces to rub on the surface of the leather. Folding the leather to keep the bark in place and then leaving it overnight. The next day they would pull and rub the leather to help soften the fibers to create their hides.
- Tanned leather’s characteristics are determined by the tanning process used.
- All tanned leather comes from animal hides that have been harvested and processed.
- Tanned leather is a luxurious material for utility and art.
It is incredible to think that a historic material like tanned leather has remained popular since its discovery. Although many artificial materials have been invented, tanned leather still remains one of the best, offering high durability and versatility with a luxurious natural look.
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