What is Tan Process and How to make Tanning Process Leather?

Here We Understand What is Tan Process, Why Should Leather Need It And How To Make Tanning Process Leather.

Tan Process

Tanning is the process of treating skins of animals to produce leather. Tanning Leather involves a process which permanently alters the protein structure of skin, making it more durable and fewer vulnerable to decomposition, and also possibly coloring it.

How to Make Tanning Process Leather

Leather making is a very complicated process. When you want to understand the Tanning Process of Leather preparation first you need to understand the layer separation of leather. Leather is split across its thickness to produce a top layer (hair side) and the under layer.

The top layer is called full grain and describes the side exposed to the elements giving it the durability and malleability it needs to be considered fine leather.
The underside is much stiffer and less durable than the top layer. This is practical for use after a coating or treatment is applied.

The process of tanning involves five different stages: Pre-Tanning, Tanning, Selecting, Dressing and Finishing. Each one of these Steps have complicated processes and requires many steps.

PRE-TANNING

Soaking: When the leather arrives at the tannery it may be soaked to extrude salts used in preserving leather. This is done in revolving drums which can hold up to 200 hides.

Liming : Hair and epidermis are removed and a solution of lime (calcium hydroxide) and sodium sulfide is applied to soften and enhance the hide for softness and flexibility needed for upholstery leather.

Splitting: The hide is split into layers. The top, or grain, layer will produce a fine, smooth grain leather. The bottom is used for suede or split leather for other uses.

TANNING

This is the process which converts pre-tanned hide into leather. 80-90% of real leathers in the world are tanned by chrome (also known as mineral) tanning. Chrome tanning uses a solution of chemicals, acids and salts (including chromium sulphate) to dye the hide. Vegetable tanning uses natural ingredients such as the bark of chestnut trees to tan the leather.

These is different types of Tanning

  • Chromium Tanning (Mineral tanning)
  • Pure Vegetable Tanning
  • Synthetic Tanning
  • Oil Tanning
  • Combination Tanning

SELECTING

After tanning, excess water is removed from the hide. Hides are then graded according to the quantity and locations of natural features and flaws. Aniline and Nubuck leathers demand the best quality hides. Heavily coated or embossed leather can utilize a lesser quality of hides.

DRESSING

Shaving – Hides are given a uniform thickness.
Dyeing – Dyes are added to color leather.
Re-tanning – Additional tanning substances are sometimes added to modify the physical characteristics of the leather to suit its final use.
Setting – A process which mechanically removes creases and excess water.
Drying – The hides are stretched dried on large frames or vacuum dried.
Trimming– The rough and ragged edges are removed.

FINISHING

To minimize the appearance of grain blemishes without losing the natural beauty of the leather product.
To give the required degree of gloss.
To ensure the leather is soft, malleable and moldable.
To give a more protective surface.
To provide a surface that can be easily cleaned.
To give special effect such as an antique look.

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