Silk Production

Silk Production. The cultivation of silkworms and silk reeling are developed in a number of southwestern European countries, in Japan, Southern China, and in the USSR—in the Central Asian and Transcaucasian republics. The cultivation of seed cocoons (eggs) is carried out in special seed plants; the seed cocoons go to the silkworm breeders, who raise the silkworms to the cocoon-forming stage. The latter are transferred to silk-reeling factories, where after stifling (to kill the pupae) and sorting, two main operations are carried out: 1) steaming in hot water (100°)—here the outer layer of the cocoon is softened and it becomes possible to separate the stuck turns of the threads; 2) unwinding—cocoons with found thread ends are given to the reelers, who lower them into a basin with water at a temperature of 50-60°; each cocoon is brought to a guide where the capture and joining of several threads into one thread occurs, the latter is wound onto a reel. Waste products—frieze (outer tangled layers of threads from the cocoon), bassonette (unwound remnants of cocoons), etc.—are processed in special silk-spinning factories. Professional hazards are as follows: 1) during the mating of male and female moths in seed plants, a large amount of dust—scales from the wings and abdomen—evaporates; this dust causes severe irritation of the mucous membranes of the respiratory tract; 2) in silk-reeling factories, large amounts of water vapor evaporate from the steaming vats and reeling basins, and the air is heated; the temperature and humidity of the air are greatly increased (20-30° with 70-80% relative humidity); on Central Asian factories t° is even higher—28-34-38° with 50-70% relative humidity. In the basins, if they are not washed frequently, decomposition of organic substances occurs, from which ammonia and hydrogen sulfide are released into the air. -Dermatoses of cocoon reelers are particularly important. In former times in Southern European countries, this disease affected a large number of workers and therefore attracted attention long ago. A detailed description of the disease was given in 1851 by Potton; but the form of the disease ('mal de bassin') that he observed (with three stages—redness, pustules, and abscesses) is now almost never encountered. An investigation of workers in a silk factory in Moscow showed that in reelers on the right hand, a series of changes develop: peeling of the epidermis, its scaling, dryness of the skin, bullous and vesicular elements, erosions, nail lesions, etc. On the left hand, the changes were expressed less sharply: redness in the interdigital folds and on the first phalanges, millet-like papules, etc.; similar lesions were found on both hands of the steaming workers. These diseases affect the workers quite frequently—in 1924/25, according to three factories in the Moscow region, there were 0.37-0.6 cases per worker per year. The cause of the development of dermatoses is considered to be the effect of a number of factors: prolonged contact with water, its temperature (especially), water hardness, substances released from the pupa, sericin, coming off with the frieze, and others. Preventive measures: to improve meteorological conditions, it is necessary to carry out measures, in general similar to those proposed for dyeing works (see Dyeing). To eliminate or reduce skin diseases, frequent changing of water in the basins (not less than once every 4 hours), maintaining its temperature not above 50°, lubricating hands with an indifferent ointment, organization of professional selection of workers, etc., are required. The question of full mechanization of the work of reelers and transition to work with cold solutions is being developed. In the further stages, silk processing does not differ from the processing of cotton fabrics (see Weavers, Spinning Production, Dyeing). Production of artificial silk. Artificial silk, a fiber obtained from cellulose through its complex processing. To obtain artificial silk, several methods have been developed: Chardonnet method (from nitrocellulose), copper-ammonia, acetate, viscose; the latter has found main application in practice, particularly in the USSR. The production process for obtaining artificial silk by the viscose method consists of the following stages: obtaining alkali-cellulose as a result of the action of caustic soda on cellulose; maturation of alkali-cellulose for 48-72 hours; treatment with carbon disulfide in rotating drums, 'barrels', for 3-4 hours (sulfidation); transfer of the resulting semi-product 'xanthate' to mixers, where a 4% solution of caustic soda is added—the product 'technical viscose' is formed; filtration of the latter and final maturation; transfer of the ready viscose by compressed air to the spinning shop, where it passes through 'spinnerets'—platinum caps with holes 0.08-0.12 mm in diameter; coming out through these holes, the viscose enters the viscous liquid (contains sulfuric acid, sodium and zinc sulfates, etc.); here it coagulates and in the form of a thick thread is fed to a centrifuge, where it is drawn and wound into packages, 'loaves'. Further processes: rewinding, desulfurization (removal of sulfur), degumming, washing, drying and sorting; the finished product is sent to textile factories. Among the hazards inherent in artificial silk production, air pollution with poisonous gases and vapors—hydrogen sulfide, carbon disulfide, and sulfur dioxide—comes to the forefront. On the Mytishchi factory near Moscow, built before the war, the content of CS₂ in the air of the xanthate department in 1925 sometimes reached 0.4-0.6 mg/l, in the spinning department—0.6-0.7 mg/l; the content of H₂S in the spinning department—0.04-1.16 mg/l. On the Leningrad factory, equipped with the latest technology, these concentrations (1933) are much lower: the content of CS₂ in the air of the spinning shop on average is 0.098 mg/l (fluctuations 0.023-0.19), the content of H₂S—0.0152 mg/l (from 0.0024 to 0.037). The mentioned hazards also cause the specific morbidity of workers in this production. This morbidity should be attributed to the effect of: 1) hydrogen sulfide; its concentrations in general do not reach values at which general acute poisoning is possible; as for small concentrations, they manifest themselves mainly as specific damage to the conjunctiva and cornea (for details see Hydrogen Sulfide). Depending on the sanitary arrangement of the factory and consequently the concentration of H₂S in the air, the number of diseases varies on different factories. According to Kaplan's data for 3 summer months of 1932, the number of cases of eye diseases per 100 workers was: on the Mytishchi factory—441.3, on the Klin factory—33.3, on the Leningrad factory—9.3. During the examination of workers in the spinning shop, cases of chronic conjunctivitis were found; among the workers of this shop, atrophic rhinitis is also common. 2) Due to the presence of significant concentrations of CS₂ in the air; cases of poisoning on Western European factories are still quite common. Serious poisonings with CS₂ on the Mytishchi factory—with pareses, paralyses, and other phenomena from the central nervous system—have not been observed; as for new enterprises in the USSR, obviously such diseases cannot be expected here; during the examination of workers in the spinning shop of the Leningrad factory (1933), only cases of vegetative neurosis, mild hysteria, and beginning neurasthenia were found. Along with better working conditions, the general socio-domestic factors in the USSR undoubtedly play a positive role. Finally, one can note skin lesions on the hands of spinners and packers (effect of caustic soda). Preventive measures are basically (except for good premises and proper equipment) reduced to the removal of harmful gases from working premises through proper ventilation. Among other measures, one can note the preliminary washing of yarn on 'loaves', mechanization of the preparation of the reducing bath, introduction of mechanical dryers, etc.