chem-Logo
An Introduction to Tannery Industry Process and Types of Tanning
An Introduction to Tannery Industry Process and Types of Tanning

The chemical compound called tannin was used to process the skins to produce leather. Tannin was derived from the bark of specific trees. Alternative methods were developed in the 1800’s, when chrome tanning and chromium salts were used instead of natural tannins. Nowadays, there are more alternatives to chrome tanning, for example zeolite tanning – which is a better option for the environment.

The tannery industry involves the processing and treatment of animal hides and skins to produce leather. The may also creates too much waste and uses large amount of water for their process. Waste water of tannery process are highly contaminated with organic matter and chemicals used for tanning. The recommendation of environmental protection agency to use effluent treatment plant for proper and Environmental friendly waste waster discharge. The main processes involved in the tannery industry are:

Raw Material Collection

 Hides and skins are collected from slaughterhouses, farms, or other sources.

Pre-Treatment

     Removal of flesh and fat

     Cleaning and washing

     Soaking to rehydrate the hides

Liming

    - Treatment with lime and other chemicals to remove natural oils and fatty acids

    - Removal of hair and flesh

Deliming

     Neutralization of the lime to prevent further degradation

Bating

    Enzymatic treatment to break down proteins and fats

    Softening and relaxation of the hides

Pickling

     Acid treatment to remove excess lime and prevent further degradation

Tanning

    - Treatment with tanning agents (chromium, vegetable tannins, etc.) to stabilize and preserve the hides

Neutralization

    Removal of excess tanning agents

Dyeing

     Coloring the leather using dyes and pigments

Fatliquoring

    Application of oils and waxes to enhance softness and flexibility

Finishing

     Treatment with chemicals and coatings to enhance appearance and performance

     Cutting, shaping, and finishing the leather into final products (shoes, handbags, etc.)

Quality Control

 Final inspection and testing to ensure the leather meets quality standards.

Additionally, some tanneries may also use specialized processes such as:

Vegetable tanning

Using plant-based tannins to produce more sustainable and eco-friendly leather

Chrome Tanning

Chrome tanning Using chromium salts to produce soft, supple leather

Chrome tanning uses chromium salts to treat animal hides, resulting in soft, supple, and water-resistant leather.

 It is a fast process that can produce leather in a day or two.

Chrome tanning is the most widely used method, accounting for over 90% of leather production.

The primary agent used in chrome tanning is trivalent chromium (Cr III).

Chrome-tanned leather is often used in footwear, handbags, garments, and upholstery due to its durability and versatility.

Alum Tanning

Alum tanning uses aluminum salts to produce soft, white leather.

It is less common than chrome tanning but still used for specific applications.

 Alum tanning is not as well-known as chrome or vegetable tanning, but it has its own unique characteristics and uses.

Semi-Chrome Tanning

Semi-chrome tanning is a combination of chrome and vegetable tanning.

It aims to balance the benefits of both methods, producing leather with a mix of characteristics.

 Semi-chrome tanning is not as widely used as chrome or vegetable tanning but offers an alternative for specific applications.

Leave a Reply

Your email address will not be published. Required fields are marked *