Leather World

Tanning of hides by any of the primitive methods was a dirty job withHttle assurance of success. The tanner was a speciaUst generating little respect in the community. In some parts of the world, this ancient prejudice against tanners exists even as of this writing (ca 1994). The tanner in primitive societies was limited to making leather using the hides or skins available locally. Tanning materials were also limited to those in local supply. Techniques were dependent on the climate as well as avadabihty of materials. The leather made was for local needs. 

The manufacture of leather foUows the same general steps for a great variety of leathers (Fig. 2). The largest category of hides taimed is catde hides. Of the cattle hides chrome tanning of unhaired hides is by far the dominant system used throughout the world. The tanning of other types of hides and skins requires variations in the systems used for cattle hides (3). 

In the second quarter of the twentieth century, with the development of poly(vinyl chloride), nylon, polyurethane, and other polymers, many new and improved leather-like materials, so-called coated fabrics (qv), were placed on the market. Shortages of leather after World War 11 led to the expansion of these leather-like materials ("man-made" leathers) to replace leather in shoes, clothing, bags, upholstery, and other items. DurabiUty and waterproof quahties superior to leather made coated fabrics advantageous, in spite of imperfection in breathabihty and flexibiUty. Demands for shoes, clothing, and other items are stiU increasing due to growing world population and urbanization. 

Vinyl-Coated Fabrics. Leather substitutes are designed to imitate the appearance of leather with its grain surface. This requirement has been accomphshed by coating substances that are capable of forming a uniform film, and was first met by plasticized poly(vinyl chloride) (PVC). A leather-like material termed vinyl-coated fabric was developed in the 1930s in the United States and Germany. Shortages of leather after World War 11 spurred the expansion of this material. 

The production of man-made leather has increased rapidly due to its high quaUty (Table 5). Production was first started in Japan, and is expanding to the world. Up to 90% is produced in the Far East, and approximately 50% is exported to the United States and European countries. 

World production expressed as 100% H2O2 approached 1.9 million tonnes in 1994 of which half was in Europe and one-fifth in the USA. The earliest and still the largest industrial use for H2O2 is as a bleach for textiles, paper pulp, straw, leather, oils and fats, etc. Domestic use as a hair bleach and a mild disinfectant has diminished somewhat. Hydrogen peroxide is also extensively used to manufacture chemicals, notably sodium perborate (p. 206) and percarbonate, which are major constituents of most domestic detergents at least in the UK and Europe. Normal formulations include 15-25% of such peroxoacid salts, though the practice is much less widespread in the USA, and the concentrations, when included at all, are usually less than 10%. 

This midsummer dawn is so early that the world seems barely to have slept. I pull on my gloves, for my hands are still cold the leather presses the Jason ring into my skin as if Louis himself touches me. Even the horses, dozing in the chill mist, hang their heads as if exhausted, with none of the scuffles and nips that horses do, as men do, to find out who is master this morning. It is sixty miles to Pontefract. We will ride it in one of these days, almost without end, that are bringing me so swiftly to my own. 

Europe is still the main market for leather products and leather produced in the developing countries, e.g. Southeast Asia, may therefore end up on the European market and to European consumers. Chemicals that are added during the production, and which stay on/in the product, will hence be transported by the product to the final markets, and there will be a chemical flow around the world through the transport of leather and leather products containing chemicals. Since the tanning industry is a chemically intensive industry, an efficient chemical management in tanneries is necessary in order to minimise the overall use of chemicals and in particular also to reduce the amount of hazardous chemicals used in order to minimise eventual health effects on the consumer. 

The Oeko-Tex label tests for and restricts a high number of chemicals in the product. It should be noted that chrome-tanned leather cannot receive the Oeko-Tex Standard 100 certificate due to stringent demands on chromium. Since around 85-90% of all leather in the world is tanned with chromium, the certificate is only valid for a minor part of the leather production. 

Like it or not, its a plastic world out there. Plastics have penetrated the traditional markets for paper, cotton, wool, wood, leather, glass, metals, and concrete. (Its a good thing you cant eat it.) The growth of plastics would be even faster if they weren t made out of such an expensive raw material, petroleum. But many of the materials they are replacing have important energy components in their creation as well. So the advances in plastics continue. 

Leather is an important material in the world economy, being used in footwear, clothing, luggage and upholstery. It is a complex substrate prepared from animal hides and skins by a long series of treatments. After the removal aU organic material and hairs the material is tanned, usually with chromium salts, which causes the protein chains to cross-link. After treating with oils or fats, to improve its handle, the leather is dyed. 

Sally runs her fingers lingeringly on the soft leather of her seat. Maybe we could learn to see 3-D objects if we were gazing delta on to our world. But how can we ever visualize 4-D objects ... 

Little other individual protective equipment emerged during the First World War beyond impregnated leather gloves and linseed oil-impregnated suits for occasional use by troops in areas where mustard gas had been employed. These items were not in general use however, and the war ended before the particular problems associated with the protection of the skin against mustard gas had been studied. The only other notable... 

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