Leather Gifts
- An Affordable Luxury -
Leather Processing
By Naeem A Syed

Animal Leather is used from the Stone Age in all countries for various purposes such as clothing, bed spreads, floor spreads for comfortable sitting, to draw water from wells and to fetch water from distant places. Hence, the process differs from place to place, people to people, who were involved in hunting, chopping and de-skinning the animals.

Ever since, man found alternatives to his clothing needs, the animal skin found its way to various other utilities such as garments of various designs, shapes and sizes, bags, pouches and wallets, footwear, saddles and belts, etc.

Normally, the skin after stripped off the slaughtered animal, finds its way in the market as processed leather within 3 weeks. During this tedious period, the leather undergoes various methods of treatment, right from salting for preserving the raw skin for the period of stacking and transportation to Leather Tanneries. Then, so collected raw skins are soaked in tanks of lime for a few days. This process swells and softens the skins to make easy removal of hair. Hair is shaved-removed after de-liming. From this stage onwards the skin is called leather. This leather under process has to be again undergo re-liming, bating, soaking in drums. For this process chemicals and tanning agents such as chromium, softening agents such as fat liquor etc. are used.

Modern Industries use large drums made of Teak wood (Sagwan), rotatable by electric motors for such tanning, softening and coloring process of the leather. The leather processed by these methods then put on hangars in a shaded place to get dried. The dried leather passes through various shaving, splitting, stretching, and polishing process till it become fully soft to the required level, color, and thickness.

Finally the processed leather is measured in Square Feet (SqFt) and DeciMetres (DCM). To have an accurate measurement, the leather is placed flat, fully stretched over the conveyor body of a measuring machine and passed through a controlled unit which electronically displays the measurement of the leather.

Leather is processed to the required softness. Every item of leather demands its own level of softness. Softness of the leather differs from product to product such as Leather Shoe Soles, Leather Saddles and Leather Cycle Seats, Leather belts for industrial, animal and human use, Footwear, Shoes, Sandals and Chappals, Leather Boxes, Bowls and Luggage Bags, Leather pouches, wallets and Ladies Hand Bags, Leather cases for several industrial instruments, gift items. All these Leather articles demand different level of softness.

Leather is called by various names during its process. The Leather Terminology used in and around Ambur :

•   Skin - From small animals such as goat, lamb, sheep, deer, dog, hare,


•   Hide - From a large animals such as Cow, Buffalo, Elephant
  
•   Raw - Stripped animal skin with hair


•   Salty Or Namkeen - Salted to stake for Transportation to Tanneries


•   Limed & Pickled - Under preliminary process after arrival in the Tannery
•   Chrome Tanned - Processed (tanned) with chromium chemical
•   Wet Blue - Chrome-tanned leather in wet and swollen condition
•   Pelt - Leather skin or Hide after removal of hair.


•   Kid - Processed leather of small lambs and goats


•   Side - one half of the full leather, generally divided vertically


•   Split - The second and third layer of Cows leather or Buffalos leather
    sliced with the help of a splitting machine.
  

Naeem Syed is the Founder And CEO of Shaadmaani.Com & AmburNet.Com. A Social Worker And Responsible Citizen of India, Naeem Syed has a couple of Websites for the benefit of Citizens of this world. He writes on Social Issues and Cultures. Naeem Syed may be contacted at http://www.Shaadmaani.Com & http://www.AmburNet.Com

In research recently posted to ES&T's Research ASAP website (es048770o), scientists from India's Central Leather Research Institute (CLRI), the largest institution of its kind in the world, describe an important step forward in reducing the water pollution from leather processing. Because the technology is green and has potential to increase the leather's economic value, experts believe it has real promise

The Central Leather Research Institute's new technology for dehairing hides results in larger pieces of leather.

Typically, sodium sulfide and lime are used to remove hair from cowhides in the production of leather. The hair is completely degraded by the process, but a sludge is left behind, says Dennis Shelly, the director of the Leather Research Institute at Texas Tech University. This protein-rich sludge is the top pollution problem of the industry and is a much bigger concern than wastes that contain the chromium used in leather tanning, he says.

"From a waste-loading perspective, the dehairing issue is a larger magnitude," explains Gary Sayler, director of the University of Tennessee at Knoxville's Center for Environmental Biotechnology. "You must remember that many of the very active countries in tanning are developing countries with much more limited capacity for treatment, let alone advanced waste treatment."

CLRI's new enzyme-based technology preserves the hair, and this should significantly decrease the environmental impact of leather processing, Shelly says. "If you can save the hair without dissolving it, you will reduce the [chemical] oxygen demand of the waste stream. And that's moving in the right direction," Shelly explains. CLRI says that the process, which uses the commercially available enzyme Biodart, reduces the chemical oxygen demand of the resulting wastewater by 53% and total solids by 26%.

"Solid waste management [is] the need of the hour in the tanning industry," says Md. Rafiq, director of KKSK Leather Processors Ltd., an Indian firm that has been field-testing CLRI's new technology and deems it promising. "Ever since the [Indian] Supreme Court ordered the closure of more than 500 tanneries in and around Tamil Nadu [in 1996], the tanners in India are really looking for 'greener' leather processing," says Jonnalagadda Raghava Rao, the paper's corresponding author. "Development and commercialization of clean and green leather processing is a major thrust of our group, as well as [the] institute's top priority," he adds. Only China's leather industry is larger than India's, Shelly says. He estimates that the leather industry is worth at least $1 trillion worldwide, annually.

The new technology helps sidestep some of what Rao calls "do-undo" approaches in leather processing. For example, the conventional approach uses lime to swell hides, then removes the compound to reduce the swelling. CLRI's new enzymatic technology avoids this step. Moreover, it can be coupled with an enzyme-based fiber-opening step so that the process "completely avoids 'undoing' steps," Rao says. KKSK Leather Processors is also testing this enzyme-based fiber-opening technology.

CRLI's new dehairing process also uses significantly less production water-"practically none," Sayler notes. "I believe this is an approach that can be used many places where bulk production proteases are available. These enzymes are cheap and easy to make and are very stable," he says. For all of these reasons, that technology "will be easier to put in place than chromium alternatives," he says.
The hair preserved by the new process can be used in the manufacture of brushes, rugs, and carpets, as well as in biocomposting, shampoos, animal feeds, and natural sunscreens, Rao says. Shelly adds that CLRI has also patented a technique for using the keratin from the hair in the tanning process.

An important side benefit of the enzymatic dehairing process is that it leaves more product, increasing the area of the leather by 8% compared with conventional processes, according to Rao. He estimates that tanners could get the equivalent of about U.S.$265 for each metric ton of raw hides they process. An increase of 8% is significant, Shelly agrees. The technology is also likely to be marketable because a growing number of automotive and furniture manufacturers, particularly in Europe, are demanding that leathers be produced using the greenest possible technologies, he says. "There are companies, like Mercedes, that require a nonchrome tanned leather," he points out.

CLRI is also actively investigating alternatives to the chromium used in conventional tanning, Rao says. The institute has developed a method based on vegetable tanning.