THE HISTORY OF LEATHER

The leather industry is one the oldest industries known to mankind. Our earliest ancestors used skins to protect their body, hands and feet. Leather is made from the skin of any animal, reptile, bird or fish through a process known as tanning. This process preserves the skin which would otherwise quickly putrefy or decay.

Today the leather industry is scientifically based. 

Research is continually carried out to ensure the product is improved using the latest technology to meet modern day needs. With few exceptions hides and skins are byproducts. Animals are reared for meat, milk and wool, not for the value of their skins. As a consequence, the tanner is not able to control the supply of raw hides. Hides are traded as a commodity all over the world on open markets and in competition with other tanners on a global basis. As a result, when demand is heavy, prices soar. Additionally even minor variations in economies and currency can cause major fluctuations in raw hide prices. The availability of cattle hides for leather is however fundamentally dependent upon consumer demand for beef. Today worldwide, at least half the leather produced goes into footwear, and around a quarter into clothing. Only around 15% goes into upholstery and the rest into small leathergoods and other consumer products. Because of its durability and comfort, leather has been used for seating purposes throughout the history of transportation and furniture. The early leathers were made from cowhide, calfskin, pigskin, deerskin, and goatskin leathers. The hides and skins coming from animals either hunted or farmed for food purposes. The present trend is for most upholstery to be made from Bovine material (that is to say cattle hides) as this is readily available and best lends itself to the modern demands of designer, producer and consumer. Far from waning in popularity, leather continues to be the material of choice for many people, not just for corporate and domestic furniture but for automotive, aviation and marine applications as well.

The Manufacture Of Upholstery Leather

  

Curing - As soon as the hide has been removed from the animal it must be protected from putrefactive bacteria. Curing is a method of short term preservation. This is achieved by either sprinkling it liberally on both sides with common salt, or by immersing it in a saturated brine solution.

Soaking- On arrival at the tannery the hides are soaked in water to remove the curing salt. This is most generally done in revolving processors holding anything from 100 to 200 hides in a load.

 Liming - The hair and epidermis are removed by treating the hides in a solution of lime (calcium hydroxide) and sodium sulphide. The hide also swells up in this process, which gives the finished leather the required softness and flexibility required for upholstery purposes. This process lasts one to two days.
Tanning - Tanning involves combining the tanning agent and the hide protein to form a stable, durable, non-putrescible leather. After liming and fleshing (the removal of fat adhering to the back of the hide) the hide is split layerwise to produce a fine, smooth grain leather after tanning. The hides are then delimed to remove all the alkalies from the liming process, this is followed by a weak enzymatic treatment called bating. This last named treatment makes the grain finer and smoother and gives the correct elasticity and plasticity in the finished leather. The final treatment before tanning makes the hide weakly acidic and is achieved either by pickling the hides in a weak acid and salt solution, or by a suitable pre-tanning process. The tanning process are of two main types, vegetable tanning and mineral tanning.

Vegetable Tanning - In this case the hide is treated with vegetable tannins found in the bark and wood of certain trees. For centuries the bark of the oak tree was used as a source of tannin, but today a more common tannin is mimosa tannin found in the bark of various species of wattle tree. Traditionally the vegetable tanning is done in pits, the hides are suspended in a series of pits or vats of tannin solution which gets progressively stronger. This process is slow and may take several weeks, or even months, before the hides are fully tanned. This method is now rarely used in the production of upholstery leather. More modern scientifically controlled processes are carried out, using drums in the later stages of the process, to accelerate the process.

Mineral Tanning - This tannage is commonly carried out with the aid of basic chromium sulphate, a mineral salt which penetrates the hide very rapidly, tanning being complete in twenty-four hours. The leather is a pale duck-egg blue in colour, and after suitable processing yields fine soft modern leather. Other mineral tannages (eg Aluminum Sulphate) are also used.

Retanning - Hides are now in the finishing stage of production. A wet drum process allows the addition of dyes, anti-mould chemicals, a re- tan agent, fat licquors to give the finished product a soft feel, and where necessary, flameproof chemicals.

Drying - Hides are dried by first of all wringing excess water out in a large mangle, or setting machine, and then by stretching the hides on a frame which is then passed through a large heating chamber.

Pigmentation and Lacquering - Finished hides will have pigments applied to the surface. This is done using a combination or a roller coated for the initial application, and a spray carousel to add subsequent coats of pigment. A top lacquer coat is applied to give the finish a layer of protection against wear and soiling.

Embossing - An embossed grain pattern is sometimes "printed" onto the leather's surface. This creates a more uniform break (the natural pattern which occurs along the folds of the hide) and will help to disguise scars and marks.

Drumming - The hides are placed in side large stainless steel drums and tumbled. During this process the natural fibres start to loosen and a soft feel (or handle) is created.

Packing - Hides are distributed from our factory in rolsl of up to 10 hides. Packing lists and full customer order details accompany the hides. We offer a next day service for goods despatched from our warehouse facility

In; http://www.dctleathers.com/ edited and adapted to be posted