Introduction
Silk production is one type of farming which even though profitable has not been well exploited around the world. Only a handful of the hundreds of countries across the continents have successfully utilized sericulture and the subsequent industrial processing to effectively make an impact on their gross domestic products. This paper shall look at the fundamentals of silk cultivation and production. To this end a comprehensive research shall be conducted with the aim of obtaining sufficient information to exhaustively cover the trade.
The research will be based on both primary and secondary data. As far as primary data is concerned, empirical data will be collected from recent studies with numbers and figures used to show the costs and economical impact silk production in countries that produce it. Like with any other professional field of study, this research has to be conducted in such a way that it offers credibility to the researcher.
In such a scientific field, the strength lies in the figures and particularly the numbers obtained from real life scenarios to support collected evidence. With this knowledge in mind, effort will be made to obtain relevant information to the particular topic in question and this will be accompanied by proper citation. Secondary data will be extracted from journals and books.
The criteria of selection for the literature will be the relevance to the research topic as well as the year of publication. Both public and private libraries as well as online libraries will be visited in order to access the data. This research will be partly evidence based and partly founded on professional research by professionals in the field.
Various articles will be studied in order to provide background information which will essentially give credibility to the final essay. This will definitely make for some interesting research and in as much most of the information will only be used for reference purposes, it will effectively came round to form the back-born of the paper. Information from the publications will serve to provide explanation as regards the basics of silk production.
This will be very crucial information that will make the research report appeal to both professionals and the general public. For the latter, it may require that some of the information obtained from the books and other publications be broken down into simple language and at the same time illustrations drawn from the most successful strategies for silk production in leading producers.
Definition and description
Silk is a natural protein fiber mainly produced by the larvae of the mulberry silkworm (Bombx mori) and is utilized in the manufacture of textiles (Scott 7). Commercial producers of silk rear the mulberry silkworms in captivity in a practice known as sericulture and the produce is harnessed from the cocoons spun by the larvae (Scott 8). There are a number of other insects such as bees and wasps which produce silk but it is only the silk generated by moth caterpillars that has been successfully used in the production of textiles (Scott 9-10).
History
The usage of silk can be traced back to China in the period around 3000BC where Lady His-Ling-Shih is said to have invented the loom and subsequently introduced the rearing of the silkworm (Scott 21-24). At the time of the discovery of silk, it was principally used by the ruler, his highest ranking dignitaries and close members of his family.
With the passage of time, lower qualities of the material were developed for use by the wealthy individuals in society. With industrialization, the material was generated in large quantities and eventually average citizens could afford to and were permitted to wear silk. China kept the secret of sericulture to itself for a very long time and used it to gain prominence in the world economy.
However, by 200BC the secret had leaked to Korea with the immigration of a huge number of Chinese and this saw China lose the monopoly it had in silk production (Scott 75-77). A century later, India had gained in on the secret and sericulture began in the country. Even with this spread of production, the trade for a long time remained a secret only known within the Middle East and it was not until the 13th century that it finally got to Europe with the entry of silk weavers into Italy (Scott 193).
Process of cultivation/derivation
Silk production is a complex and time consuming process. Traditionally, men tend to the mulberry trees, leaves of which are the only food that the silkworms consume, while women are tasked with the responsibility of feeding the silkworms. Timing and climatic conditions are the primary determinants of the successful production of silk mainly because the insects do not generate the product on demand.
The silkworms have to be fed every few hours irrespective of the time of day. If all the ideal conditions are met silkworms spin cocoons for a number of subsequent days and each cocoon is only composed of one strand that is a number of thousands of feet in length.
To produce one pound of silk, one requires over 1900 silkworms. The first step of the sericulture process is the cleaning of the silkworm eggs after which the larvae are hatched and spread on trays where an intensive feeding process is carried out. As the worms grow, mats are stretched on frames and it is here that the silkworms are introduced when they are ready to spin.
The silkworms consume the mulberry leaves and then secrete a protein-like substance through the head to cover its anterior region. The spinning process happens in a duration of about one week and once a cocoon is complete, it is placed in hot water which essentially kills the silkworm and loosens the filaments (Scott 243). The cocoon is left floating on water. The cocoons are then collected and then delivered to a factory known as a filature.
Process of Production (including system/machinery of production and quality control) -Science and Technology of Production
Once the cocoons are taken to filature, the silk is unwound from the cocoons and the strands collected into skeins (Schoeser 237). The following industrial processes are applied on the silk in the filature.
Sorting-the cocoons are categorized into groups depending on the colour, texture, size and shapes because these characteristics eventually influence the eventual quality of the yarn.
Sericin Softening-Individual silk filaments are made of two strands of fibroin. The fibroin strands are held together by a substance known as sericin and it has to be softened in order to allow the filament to be unwound in one continous strand. The softening process is applied by passing the sorted cocoons through a chain of hot and cold immersions.
Filament reeling-once the silk filaments have been unwound from the cocoon, they are combined to make a strand of raw silk. Depending on the needs of the buyers, three to ten strands are wound together in order to produced the required thickness of the thread.
Bailing-once the filament has been reeled into skeins, it is packaged into small loads known as books. Each book weighs between two and four kilograms and several books are collected into bales ready for shipping to millers.
Location of Production/ Production statistics
More than thirty countries across the world produce silk. Over the past three centuries, the production of silk has gone up two-fold but China and India still remain the top producers of the product. China produces approximately 54% of the global silk while India produces an average of 14 % of the world’s silk (Datta 28-29).
In the year 2005, China produced about 300,000 tones of silk while India contributed approximately 80, 000 tones to the global silk production (Datta 29). Other top producers include Uzbekistan, Brazil, Iran, Thailand, Vietnam, Romania and Japan (Datta 28).
Fibre structure/composition
Silk fibers have a triangular cross section that is 5-1-9.9 μm wide. Textile materials produced using silk have a shimmering appearance and this is mainly attributed to the triangular structure of the fiber which ends up refracting light at various angles hence producing a variety of colors. Silk is very smooth but is not slippery like most synthetic fibers. The fabric is also vey strong but tends to lose over one fifth of its strength when wet. Silk is moderately elastic.
Fiber Qualities/Properties/Classification (including Chemical Properties).
Silk has a very high tensile strength and it can be subjected to intense pressure without getting destroyed. However, like with all other fabrics continuous use and abrasion ends up wearing it. Silk is mainly made up of sericin and fibroin (Schoeser 232-234). Fibroin forms the general structure of the silk while sericin is a gummy material that keeps the filament together. Fibroin is composed of the amino acids Gly-Ser-Gly-Ala-Gly-Ala (Schoeser 233).
This structure takes the form of beta pleated sheets. Hydorgen links are evident between the chains. Glycine is present in high quantities and this makes the material tightly packed hence increasing its strength. Depending on the level of refinement, silk can take different appearances.
Raw silk looks syntentic and greatly resembles cotton. Refined silk and that made of smaller yarn gets the luster and fineness that is associated with the fabric. Because silk is protein in nature, it is sensitive to a number of chemicals and is easily destroyed by prolonged exposure to alkalines, acids and oils. Sulight and age makes it brittle.
Process/Processes from fiber to yarn (spinning) till finished fabric – Science and Technology.
At the milling factories, the silk is converted into yarn by a procedure known as throwing. Throwing is the silk equivalent of spinning. The skeins are sorted according to their different attributes including colour, size and length and then washed in warm soapy water in order to soften the seracin (Datta 158).
Once the skeins are dry, they are put on reels from which they are rolled around bobbins. In the winding process, the silk strands are doubled and twisted in desired directions in order to create the different types of yarn. The yarn is then run through rollers in order to make the diameter standard throughout the strand. Any seracin that is left on the yarn is washed out using warm-soapy water in a procedure known as degumming (Datta, 159).
Classification of yarn
There are for primary types of yarn depending on the arrangement of the silk filaments in the final product. These are Thrown singles, Tram, Crepe and Organzine (Wulfhorst, Gries and Veit 30). Thrown singles are composed of 3-8 silk filaments which are wound together and in just one direction to come up with a single strand (Wulfhorst, Gries and Veit 30). In a Tram, two or four untwisted singles are twisted slightly to create a yarn that is specifically used for filling.
A Crepe is made up of two raw silk filaments which are wound together with one headed in an S direction and the other in a Z direction (Wulfhorst, Gries and Veit 31). Organzine is silk yarn that is made up of more than one singles that have been twisted in a Z direction which are combined and twisted around each other in an S direction (Wulfhorst, Gries and Veit 32). This type of yarn is primarily used to make warps.
Fabric construction
There are two primary processes for fabric construction used for silk. These are weaving and knitting. The two have been briefly explained below:
Weaving- in this process, two different types of yarn, the warp and the filling, are combined together in an interlacing pattern on a loom hence forming the fabric (Maxwell 162). The warps cross from the posterior to the anterior area of the loom in a lengthwise manner while the fillings run crosswise over the warps (Maxwell 160).
Knitting-Once the weaving stage is complete, knitting follows. A knitting frame or a knitting loom is used in the process and various types of fabrics are produced depending on the desired output (Wulfhorst, Gries and Veit 156-161). The knitting process for silk to be used in making clothing is different from that for making interior design fabrics.
Finishes/dyes/prints
Various finishing approaches are utilized on different silk material to improve the appearance, durability and texture. The most common finishing processes are Calendering, Cireing, Singeing, Steaming, Pressing, Lustering and Weighting (Datta 143). Calendering and Cireing are used to improve the luster of the silk while Singeing is used to smoothen the fabrics. Steaming is used to raise the pile weaves while pressing and lustering are applied to get rid of the wrinkling from the finished material.
Pressing is done by passing the material through heated rollers and then the luster of the fabric is enhanced by putting it in a diluted acid. Weighting is a finishing method that is unique to silk. This is because a substantial amount of the material’s weight is lost during the preliminary production processes. Weighting is done purely as a profitability strategy because the manufacturers buy the silk by weight and therefore the finished product has to be the same weight as the raw material if the process is to make economic sense.
Weighting is done by lacing the fabric with metallic elements like sodium phosphate and iron salt. The metallic elements are added into the dye. Weighted silk is less compact in terms of the weaving structure as compared to unweighted silk and slightly less of it is used in creating the fabric. Besides reducing the cost of the silk, weighting also makes the fabric crisp and firm, and gives it a characteristic luster.
Modifications
Various chemical regimens have been developed in order to enhance the physical and chemical characteristics that give silk the kind of superior characteristics it has. One of the most popular techniques is using Diazonium Coupling to modify the arrangement of fibroin on the silk hence increasing its tensile strength. Lithium Chloride can also be used to modify the sericin in the silk hence making it less adhesive in order to make the unwinding and yarn-development processes much easier and economical.
Performances and application/Use in interior design
Silk has been branded the strongest natural material across the globe and it has found usage in a number of areas including cloth making and interior design (Llwellyn 9-15). Silk is very popular in making wedding and evening gowns, dress shirts, skirts and scarves for women and suits, dress shirts, ties and pocket squares for women (Llwellyn 16). In interior design, silk is commonly used in making drapes and wall coverings as well as bed sheets, pillow cases, throw covers and tablecloths (Llwellyn 29).
Analysis of the market
The silk market is concentrated in the Middle East where most of the wholesale trade takes place. In China for example the silk market is based in Hangzhou City where there are more than six hundred silk enterprises that specialize in all types of silk fabrics. The silk produced by this market is sold locally as well as abroad in countries like the United States and Britain.
China’s silk export approximated US $ 5.6 billion last year with the countries raw silk production accounting for over three quarters of the global silk production. India, the second largest producer of silk, exports most of its products the Europe and America. The United States is the largest importer of Indian Silk taking about 23% of the silk produced in India.
Associations
The various countries known for the production of silk have well structured organizations aimed at ensuring that the product gains prominence by effectively protecting both the farmers and the processors from exploitation. Below is a list of such associations in the world’s topmost producers of the product.
China (PRC)
Chinese Silk Association- This association ensures that the farmers of silk are well educated on the best practices for the raising of the mulberry silkworms and the harvesting of the product. The organization also ensures that the processors of the silk get a proper market.
China (Taiwan)
Taiwan Silk and Filament Weaving Association– This is a nationwide organization and it represents both the silk cultivators and the processors of the product.
India
Silk and Silk Mill Research Association- This organization carries out research on the effective practices for the production of silk as well as the best methods for processing the product in order to obtain the best qualities.
Silk Association of India- The membership of this association includes cultivators and processors. The organization ensures that the farmers are not exploited and that the processors get the best price for the commodity.
Uzbekistan
Uzbekistan Silk Association- This is a well structured organization that carries out both production and market research on behalf of the cultivators and the manufacturers of silk.
Samples of silk fabric
Works Cited
Datta, R.K. Global Silk Industry: A Complete Source Book. New Delhi: APH Publishing, 2007. Print.
Llwellyn, Claire. Silk. Connecticut: Scholastic Library Pub, 2002. Print.
Maxwell, Robyn J. Textiles of Southeast Asia: tradition, trade and transformation. Tuttle Publishing, 2003. Print.
Schoeser, Mary. Silk. New Haven: Yale University Press, 2007. Print.
Scott, Philippa. The Book of Silk. London: Thames & Hudson, 1993. Print.
Wulfhorst, Burkhard, Thomas Gries and Dieter Veit. Textile technology. Germany: Hanser Verlag, 2006. Print.