The year of the pig15 April 2015
Pigskin remains the largest potential raw material resource to be used by the leather industry worldwide. Professor Dobre Jovanoski, a leather expert and independent consultant, explains why this product should be duly considered by the industry, and how to distinguish the right raw material and process for the job.
The production of pigskins has always found a home where raw material and experience are found, traditionally in East Asia, Eastern Europe and the US.
The worldwide total number for pigs slaughtered per annum is around one billion, but only about 200 million skins are transformed into leather (20%). That is 200 million square metres of grain leather, plus 50 million square metres of splits, or 15% of the worldwide leather production.
At present, the strongest pigskin production comes from the Far East, especially in China, which is by far the largest pigskin producer in the world, with one of the biggest pigskin-leather bases in Shuitou, Pingyang Zhejiang province. The country has roughly 500 million live head of pigs at any given moment in time. It produces nearly 100 million pieces of raw pigskin every year, which is approximately 1.5 billion square feet of finished pigskin leathers.
The emergence of a middle class in China and other developing and emerging nations across the globe has led experts to recognise that the beautiful, natural, soft and practical nature of pigskin leather has become more in demand. Metallic pearlised lining leather, in particular, has become very popular.
The worldwide shortage of raw stock has also increased the interest in pigskins, and the range of skins that can be manufactured from this interesting raw material offers originality and unexplored potential for tomorrow's fashion trends.
Some countries do have issues with pigskin production with disadvantages including seriously heavy taxation on some tanneries and certain enterprises have come under a heavy burden. However, these enterprises could improve their fortunes simply by decreasing production costs, uniting staff, improving technology and developing new products - especially for export.
Go to market
The quantity of this raw material used in leather production is limited as not all slaughtered pigs are flayed; the skin is often retained with the meat, or used in the production of gelatine or in collagen products.
Raw pigskins are usually cured or preserved with salt (salted), but are also dryed or limed pelts in China. They are typical whole skins with side parts and seldom like backs (butt with neck).
Skins of wild peccary pig boars of South America are a special type used for the production of glove and garment leather.
Suede and nappa remain the major production lines for pigskin garment leathers, but there is development into new areas such as nappalan-type finishes on the flesh side, double-face, nubuck and pull-up effects.
With regard to softness and commercial appearance, these types of pigskin leather can compete with sheep and goatskin, especially when considering price.
Pigskins have also been deemed appropriate for furniture and the automotive industry by some experts. Though, in other areas of the sector, heavier raw stock is mostly used for shoe upper, leather goods, upholstery and technical types of leathers.
Pigskin splits can be used for the production of all types of leather and are well known for their hard-wearing and easy-care properties.
Attention to the process details
Peculiarities of pigskin include hair roots penetrating through the entire cross-section of the skin, which is the biggest problem for it to be deemed 'very good' leather.
Attention also needs to be paid to a well-balanced and careful chemical process, which is based on extensive experience in areas such as:
- Degreasing: a thorough process is necessary to avoid uneven shades and spues formed by solid fats migrating to the leather's surface. BASF has a compact system with new high-performance and specific combinations that are ecologically acceptable, such as Eusapon S and D. There is also the newest speciality enzyme preparation Basozym DC 503 (lipase).
- Liming: this is essential for the softness of leathers, and has to be relatively long and intensive compared with other leather types, because of the specific structure of pigskin. Some tanneries extend the lime/sulphide process with a pure lime - reliming. BASF liming products include Basozym L10, Mollescal LS or AB.
- Bating: this is an important process for garment leathers for softness. BASF has a product specially designed for pigskin - Basozym CP10. It is mixture of enzymes that effectively removes hair roots and scuds. The pelts are very clean and pale in colour. The leather can be dyed to brilliant level shades resulting in smooth, fine-grained leather with full belly and shanks.
- Tanning: an intensive and long pickle prior to tannage helps to level out the structural differences between the neck and butt with the chrome tannage based on masked chrome salts. BASF has Chromitan types and Implenal DC Liq for Cr-fixation.
- Neutralisation: this procedure on garment leathers should be very intensive. BASF has Tamol (GA, M, NA - for the elimination of CrVI) for this.
- Fatliquoring and waterproofing: the right selection of fatliquors and/or water-repellents is a critical step for optimum handle and feel towards making mellow garment leathers.
- Dyeing: for suede and nubuck, dyeing is the essential key to success. The selection and application of dyes directly influence the quality. The metal complex dyes provide good light fastness and wet-crock resistance with the highest standards possible. The penetration and compatibility of dyes is very important to ensure levelness. For heavy or dark shades, a sandwich meted of dyeing with a cationic treatment is used with the selection and application of auxiliaries being critical.
What's in a name
Pigskin is leather made from the skin of the domestic pig. The term is not to be applied to leather made from the flesh split of pigskins. In Germany, Italy and Spain, the term also covers leather from the skin of a wild pig. Other definitions include:
- Common: the domestic species of sus scrofa (wild boar), developed from the wild species.
- Landrase: a Danish, lop-eared breed of pig, especially favoured for bacon production.
- Store: is a pig specially fed and housed for fattening.
- Female pig sow: an adult female pig, especially a domestic one used for breeding.
- Young sow: a female young pig.
- Swine: a term used for an animal of the family suidae (bristle-bearing, non-ruminant, even-toed ungulates), especially for the common species sus scofa.
- Peccary: a South and Central American wild pig of the genus dycotyles. It has a skin used for making so-called 'hogskin' gloves. Grain leather, made from a wild pig indigenous to Mexico, Central American countries, Brazil and Argentina, mainly for glaving.
- Peccary skin: is a grain gloving leather made from a wild pig.