Reeling silk

Both degumming and partial degumming are only suitable for reeled silk (greige). These finishing processes are insignificant where schappe and bourette silks are concerned, since these are freed from their gum in the early stages of preparation before spinning [66]. 

Fig. 10.9 Loss tangent profiles of force-reeled silk fibers (naturally spun, postdrawn sample, slack-stored and not-postdrawn and dry-stored and not-postdrawn).

Fiber length (mm) 10-60 technical fiber 450-800 elementary fiber 10-40 fine wool 55-75 coarse wool 150-300 reel silk 300-1000 m schappe silk 50-250 m... 

Reeled silk is a filament yarn produced by the simultaneous reeling of several cocoons, also called grege yarn. Spiral or twisted yarns are called trame, organzine, or grenadine. 

The titer-denier (Td) system is used to measure the fineness of reeled silk, synthetic fibers, and yarns. According to DIN 60910, this system is now allowed only for conversion purposes. The equation for the Td system is... 

Silk is an animal fiber valued for its texture, strength, and luster. First prepared in ancient China, silk fabric was expensive, luxurious, and soft its popularity led to the development of a trade route known as the Silk Road leading from Asia to Europe. Early American entrepreneurs such as Benjamin Franklin promoted the silk industry in the colonies. Silkworms spin cocoons that are collected, steamed, and unwound to obtain the silk fiber by a process known as reeling. A number of fibers are twisted together to form a thread of raw silk. Threads are combined, cleaned, stretched, dyed, and woven into fine fabrics. Silk fibers have great tensile strength and are sometimes used in cordage. 

The properties of natural silk are affected by numerous factors, such as nutrition, temperature, hydration state, extension rate, reeling speed (ICnight et al., 2000 Madsen et al., 1999 Riekel et al., 1999 Vollrath and ICnight, 1999 Vollrath et al., 2001), and spinning medium during the manufacture (Chen et al.,... 

The natural gum, sericin is normally left on the silk during reeling, throwing and weaving. It acts as a size whieh proteets the fiber from mechanical injury. The gum is removed from finished yams or fabries, usually by boiling whit soap and water [73].The fibers were heated in an aqueous Na2C03 (0.02 M) or 0.5 %( w/w) NaHCOs and rinsed with water to extract sericin. [77, 75]. 

Commercial and Artificial Processing. CommerciaUy, silkworm cocoons are extracted in hot soapy water to remove the sticky sericin protein. The remaining fibroin or stmctural silk is reeled onto spools, yielding approximately 300—1200 m of usable thread per cocoon. These threads can be dyed or modified for textile appHcations. Production levels of silk textiles in 1992 were 67,000 metric tons worldwide. The highest levels were in China, at 30,000 t, foUowed byJapan, at 17,000 t, and other Asian and Oceanian countries, at 14,000 t (24). Less than 3000 metric tons are produced annuaUy in each of eastern Europe, western Europe, and Latin America almost no production exists in North America, the Middle East, or Africa. 1993 projections were for a continued worldwide increase in silk textile production to 75,000 metric tons by 1997 and 90,000 metric tons by 2002 (24). 

The next step in sericulture is to unwind the cocoon. This process is called reeling. To produce uniform strands of raw silk for commercial use, filaments of 5-10 cocoons are combined into a single thread. To do this, the cocoons are first soaked in hot water. After the ends of the filaments have been located, the filaments are passed through porcelain guides where they are twisted into fibers of uniform length and regularity. Reeling may be done automatically or by hand. 

Thrown silk or grege consists of two or more threads of raw silk reeled together and given a slight twist. Thrown silk is used for making organzine and tram. 

The separation of the germ, gluten and starch is accomplished in the wet process by the reels. These are long open cylinders covered with perforated copper or silk depending upon the work to be done by the reel. The grams are separated by the coarse copper reels. The starch is separated from the coarse and fine feed, by file coarse feed reels, the No. 9, the No. 12 and the No. 17 silk reels. Sometimes even No. 20 silk reels are used. 

Over 90% of commercially produced silk is by the domesticated silkworm Bombyx mori. This is a monophagous insect with a diet that is restricted to the leaves of white mulberries, Moms alba and Moms indica. The production of silk requires the maintenance of mulberry plantations (moriculture), the rearing of silkworms to the cocoon spinning stage (sericulture) and finally the unravelling of cocoons (reeling). Each subsection of the production will be outlined below. 

Firewood and water consumption in silk reeling UnraveUing cocoons requires between 3660 and 5440 KJ of wood per kg fresh cocoon. Mande et al. (2000)... 

Leaves unsuitable for silkworm rearing are generally fed to hvestock. We have modelled them as a substitute for intensive hay (Ecoinvent), as mulberry leaves have nutritional properties similar to alfalfa hay (Doran et al., 2007). Mulberry woody biomass is treated as a substitute for eucalyptus firewood, with corrections for lower HHV. Rearing waste is assumed to reduce the need of imported FYM, as they have a similar composition (Dandin et al., 2003) and composted waste makes effective fertili2er for mulberry. There are few products directly comparable to pupae, sUk, and silk waste from reeling that are exclusively allocated based on their economic value. 

Kathari, V.P., Patil, B.G., Das, S., 2011. An energy efficient re-reeling process for silk reeling industry to reduce deforestation. Indian Journal of Fibre Textile Research 36, 96-98. 

Mande, S., Pai, B., Kishore, V.V.N., 2000. Study of stoves used in the silk-reeling industry. Biomass and Bioenergy 19, 51—61. 

Yong-woo, L., 1999. Silk Reeling and Testing Manual. FAO, Rome, http //www.fao.org/ docrep/x2099e/x2099e00.HTM (accessed October 2014). 

Stifled cocoons are sorted, and then brushed to find filaments. Several filaments are gathered together and wound onto a wheel (reeling). Each cocoon yields approximately 1000 m of silk filament, known as raw silk, or silk-in-the gum, fibre. 

Wild silk (Tussah) production cannot be reeled, because cocoons are harvested after the moth has matured and left. As an average yield one may take 30 kg mulberry leaves for 1 kg cocoon. As the harvesting of the silk from the cocoon requires the killing of the larvae, silk-culture has been criticized by animal rights activists. 

To recover the silk, the pupae are killed with steam or hot air. By immersing the cocoons in hot water, the silk glue is softened. Rotating brushes catch the end of the silk fiber and 4-10 of the threads are wound together onto a reel and dried. Of the 3 000-4 000 m of thread per cocoon, only about 90 m can be unwound. The outer and inner layers are too impure and are used along with damaged cocoons in schappe spinning. 

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