What is tanning in leather products manufacturing?

The leather industry in India is the oldest manufacturing industry. This industry focuses on employment generation and provides jobs to around 4.4 million people. With consistent high export earnings, this industry is one of India’s top 10 forex earners.

India is among the best locations for the leather industry because raw materials are available here in abundance. Around 11% of the world’s goat and sheep population and 20% of the world’s buffalo and cattle population exist in India, an essential raw material in this industry.

Leather Product Production Process 

Processing leather requires high accuracy to make products of the best finish. The process begins with animal hide and ends with leather pieces to make various products like bags, belts, furniture, shoes, wallets and other clothing. 

Tanning In Leather Products Manufacturing 

Tanning is the first step in the leather production process once the hide is cleansed from salt, hair, dirt and blood. The hide needs to be processed before being used in making leather products. Such a process is known as tanning. Before going through the tanning process, the animal’s hide or skin goes through several stages, including soaking, liming, unhairing, fleshing, degreasing, bleaching, bating, pickling, and depickling. 

The tanning process involves converting the proteins of the animal hide into a stable material by stopping decomposition and protecting the hide. Through the process, the inflexible hide is transformed into being flexible. Depending upon the end use of the leather, different tanning processes and materials are used. 

Below are some methods used in tanning in leather products manufacturing. 

• Chrome tanning

It is the most widely used tanning process, which involves soaking the animal skin or hide in tubs containing acidic salts and chromium tanning agents. Once the skin absorbs the chromium salts, the acidity is reduced. After the hide is tanned with chromium salts, the wet hide gets a pale blue colour. This is why they are also called “wet blue hides”. 

• Vegetable tanning

This type of tanning has been used since ancient times. It takes longer to tan hide with this process than chrome tanning. It involves the use of tannins present in the barks and leaves of the trees. After the preparation phase, the animal skin is put into the tanning pit, where they are soaked in drums containing tanning solutions of varying strengths. For two to three months, the tanners move the animal hide from one drum to another to help the tanning agents get into the skin, making the hide distinct in appearance. 

• Brain tanning

Commonly used by hunters, this type of tanning is used to preserve the hide of freshly killed animals. The brain tanning process differs from one person to another. However, the commonly used method involves first cleansing the animal skin properly and removing the fat, flesh and membrane that cover the inside of the hide. Then, the hide is washed thoroughly and extended on a frame by the tanner. A solution is prepared by mixing the mashed brain of the animal with warm water and is applied to the animal hide. Once completed, the hide is smoked to finish the process. 

• Synthetic tanning

Used as an alternative process to chrome tanning, synthetic tanning works in combination with other forms of tanning. It uses artificial tanning agents that make the leather soft and give them a bright colour. Artificial agents such as glutaraldehyde, formaldehyde, and acrylates are used in this type of tanning. Due to its bright colour, it is called ‘wet white hides”. 

This process is commonly used to make leathers that can be washed and dry cleaned.

Need For Leather Tanning 

Tanning is crucial for leather to prevent it from putrefying. If the leather is left untanned, it will rot, making it unfit for further production of products. 

Tanning prepares the leather for various end applications by stabilising the proteins of the raw animal hide. 

Production Centres in India

The production centres for leather products are spread across various cities in India. Kolkata, Ambur, Chennai, Kanpur, Bengaluru, Jalandhar, Hyderabad, Ranipet, Trichy, and Delhi are the major production centres of India. 

The Indian leather industry is blessed with the availability of raw materials. According to the latest census, India is in the top rank in livestock holding. This livestock provides the raw materials required for the leather industry.

Conclusion 

Tanning is a significant part of leather products manufacturing. Each tanning process contributes to making the leather fit for making products such as bags, belts, furniture, shoes, wallets and other clothing. Methods of tanning range from brain tanning to chrome tanning, so they are available at varying prices, thicknesses, colours and quality. 

There are over 2,000 tanneries in India scattered in small and large scale cottage industries all over India.