How Is Leather Tanned and Processed?

Posted by The Green Tanners on 11th Jun 2024

How Is Leather Tanned and Processed?

Introduction

Tanning is a key step in making leather. It involves treating animal skins to make them soft, flexible, durable, and resistant to decay. This makes the leather good for making leather jacketsleather bags, and leather aprons. A tannery is where the skins are processed. Most tanneries are near slaughterhouses because they need fresh hides, but some tanneries are separate and get skins from nearby farms and butcher shops. Before tanning, the skins go through several steps. They are cleaned of dirt, hair, fat, blood, oil, and grease. Then they are soaked in hot water for a few hours to soften them. After soaking, the skins are rinsed and dried. They are treated with chemicals to remove oils and fats and to stop bacteria growth. Finally, the skins are tanned to make them tougher, ready for making leather goods.

How Leather is Made?

Primary tanning transforms pre-treated animal hides into leather by preventing them from decomposing. The hides are placed in a large drum with a solution containing either chromium salts or plant-based tanning agents. The drum rotates for up to eight hours, allowing the solution to preserve and soften the leather.

Why do we Tan Leather?

Leather is a natural material that can break down over time. Tanning helps protect leather from bacteria, mold, and insects. It also makes leather stronger, more flexible, and less likely to dry out, crack, or tear. Without tanning, leather goods would fall apart quickly and could not be used for clothes, shoes, furniture, or other items. Tanning keeps the leather's natural oils, making it soft and water-resistant. There are different ways to tan leather, each with its own pros and cons. The two most common methods are vegetable tanning and chrome tanning. Vegetable tanning is better for the environment but does not last as long and needs more care.

                                    

What are the different leather tanning methods

There are three different ways for leather tanning:

Chromium tanning

Chromium tanning, also known as chrome tanning, is the most common way to tan leather around the world. It uses a tanning agent called chromium sulfate, which is why it's named chrome tanning. This method is relatively new, invented just 157 years ago in 1858, but it has become very popular since then.

Vegetable Leather Tanning

Vegetable-tanned leather is made by soaking animal hide in water or saltwater to remove the fur and soften the hide. Then, oils and waxes from plants are added to make the leather soft and flexible. 

Semi chrome leather tanning method

Semi chrome tanning leather is actually mix of chromium tanning and vegetable tanning. This methods is used with the chrome tanning methods. This leads to the final product that get your the final durable flexible and aesthetic leather.

What is Leather Tanning Process?

Leather tanning is pretty much complicated and undergoes by the five different stages: the steps are:

  1. Pre tanning
  2. Tanning
  3. Selecting
  4. Dressing
  5. Finishing

Step 1 : Pre-Tanning

Soaking

When the leather arrives at the tannery, it is soaked to remove the salt used for preservation. It is then washed in water to clean it and smooth out any folds. This washing happens in a rotating drum that can hold up to 200 hides.

Pressing

The pressing process removes extra water and stretches the hides.

Splitting

The outer surface of the hide, called the grain, is separated from the rest of the hide using a machine.

Step 2: Tanning

This step turns pre-tanned leather into finished leather. Common tanning methods include mineral tanning, vegetable tanning, synthetic tanning, oil tanning, and combination tanning.

Step 3: Selecting

After tanning, excess water is rainsed from the leather. The leathers are then graded based on their natural features and flaws.

Step 4: Dressing

Leather dressing includes: 

  • Shaving: Making the hide a uniform thickness.
  • Dyeing: Giving the hide its softness, color, and stability.
  • Drying: Using special equipment to remove water from the hide.
  • Trimming: Cutting and sorting the hide.

Step 5: Finishing

Finishing improves the leather's performance, protects it from getting wet and dirty, and hides imperfections while keeping its natural look. This step also adjusts the leather's surface properties like gloss and texture.

                                         

Conclusion

Making leather is an amazing thing. It needs science and smart ideas from people. You have to know a lot, be good at it, and have done it before to make leather. It takes a long time and practice to make it just right. If you have anything made of leather, you should stop and think about all the work that went into making it.

FAQs

1.How Does Tanning Leather Work?

Tanning leather involves preserving animal hides or skins by treating them with tannins. Tannins are natural acidic substances found in plants. This process makes the leather stronger and less likely to decay.

2. What Chemicals Are Used in Tanning Leather?

Different chemicals are used in tanning leather based on the desired final product. The most common ones are chromium, vegetable oils, and tannins.

3. How to Get Rid of the Tanning Leather Smell?

To remove the tanning leather smell, you can:

  • Wash the leather with mild soap and water.
  • Dry the leather completely.
  • Apply a leather conditioner.

4. What Oil Do They Use When Tanning Leather?

Various oils can be used to tan leather, but the most common one is chromatic oil. This oil helps to preserve the leather and keep it flexible.