Tasks to the text. I.What is this text about?

I. What is this text about?

II. Define the type of the text

III. Define the scheme of the text

IV. Make the semantic model of the text

V. Find key words.

VI. Make a graph of the text.

VII. Answer the questions:

1. Why are textile tests necessary?

2. Can you explain the term “durability”?

3. Which tests are possible when buying fabrics?

VIII. Put three questions to the text.

IX. Write the summery of the text.

X. Entitle the text.

Text 9

(https://www.oldandsold.com/articles04/textiles24.shtml)

Silk, the most valuable of all textiles, has more imitations than any other fiber. More processes have been invented to preserve the appearance of genuineness while utilizing cheaper fibers, than in any other textile industry. Silk fabrics are cheapened in at least seven ways: spun silk is introduced in place of thrown silk; wild silks, such as tussah, are used in place of mulberry silk; the silk fiber is weighted with tannin and mineral salts; artificial silk has been produced which in appearance rivals true silk; cotton and linen are given finishes to resemble silk (mercerizing); silk is mixed with wool for fancy effects; silk is mixed with cotton or other vegetable fibers. Spun silk is often very difficult to distinguish from thrown silk. Under the microscope the presence of spun silk can be determined by two facts. First, the fibers of waste silk are usually irregular in form; second, the sericin, or gum, is irregular in waste or spun silk. These facts are accounted for by the fact that the waste silk comes from the parts of the cocoons that do not reel off readily. When it is desired to determine whether wild silk, such as tussah, yamanai, or senegal, enters into the structure of a silk fabric, one of the best tests is to prepare a solution of chromic acid as follows: dissolve chromic acid in cold water until the water will dissolve no more. Add an equal volume of pure water. Place the suspected silk sample in this solution and bring it to a boil. True silk, that is, mulberry silk, will dissolve within a minute after boiling begins, while tussah and other wild varieties will remain insoluble for at least three minutes. Weighting of silk can usually be detected by the burning test. Separate threads from the warp and the weft are set on fire with a burning match. Pure silk burns very badly and stops burning as soon as the burning match has been removed. Practically no ash is formed (less than one per cent), and the end of the fiber left unburned takes the shape of a little bulb. Weighted fibers, when burned, leave a considerable amount of ash, and the entire thread may keep its shape after being burned. To determine just what weighting substances are used is a subject for a more technical treatise than this. Artificial silks made from cellulose, cotton, wood pulp, or other vegetable substances can be distinguished from true silk by the fire test. All cellulose silks burn readily and give off no odor; true silk burns badly and gives off the odor of burnt feathers. Artificial silks, as a rule, are not so strong as true silk and not so elastic. When wet, artificial silks now on the market swell and become weak, whereas no such effect takes place in true silk. Another chemical test is frequently used to distinguish true silk from the artificial. Dissolve ten parts copper sulphate in one hundred parts water and add five parts glycerine. A white precipitate will form. Add enough caustic potash solution to dissolve this precipitate. To perform the test, immerse the suspected sample in this solution at ordinary room temperature. True silk will dissolve almost at once. Artificial silk will not dissolve. To distinguish between silk and cotton or other vegetable fiber, apply the same test that was used to distinguish between wool and cotton, namely, boiling for fifteen minutes in a caustic potash solution. The silk dissolves, but the vegetable fiber is in no way affected. Another method is to prepare a solution of fuchsine, a dyestuff, and then decolorize it by adding caustic potash or caustic soda solution drop by drop until the color disappears. A sample of cloth made up of silk and cotton is immersed in this liquid for half an hour, and then washed carefully. When taken out, the silk, if there is any in the cloth, is red, while the cotton remains colorless. Mercerized cotton may be determined as follows. A solution is prepared by dissolving five ounces of potassium iodide in about a pint of water. To this solution add one or two ounces of iodine, and mix with another solution made by dissolving thirty ounces of zinc chloride in twelve ounces of water. The cloth sample should first be soaked in water, immersed in this prepared solution for three minutes, and then rinsed in water. Mercerized cotton will have a deep blue color, while unmercerized cotton will wash out white. To distinguish mercerized cotton from silk in the same fabric, use the same tests as for ordinary cotton and silk mixtures. Silk and wool mixtures may be tested by immersing the fabric sample in a solution of zinc chloride of 1.7 specific gravity. In this solution silk dissolves, but wool is unaffected. Another chemical method of separating wool and silk is boiling the fabric sample in strong hydrochloric acid for fifteen minutes. In that time the silk will have dissolved, while the wool will remain intact. Silk that is mixed with cotton or wool can often be studied most easily by means of a magnifying glass or linen tester such as has already been described. The true silk fibers can usually be distinguished by sight and the proportion of true silk to adulterant or other component in the mixture fairly approximated.

Tasks:

I. What is this text about?

II. Define the type of the text.

III. Define the scheme of the text.

IV. Make the semantic model of the text.

V. Find key words.

VI. Make a graph of the text.

VII. Answer the questions:

1. What are the reasons of such a great number of imitations of silk?

2. Is it easy to differentiate natural silk from its imitations?

3. What can be determined by the fire test?

VIII. Put three questions to the text.

IX. Write the summery of the text.

X. Entitle the text.

Text 10

(https://www.textileworld.com/Articles/2009/October/News)

Italy-based Comez S.P.A. − a producer of crochet knitting, warp knitting and narrow weaving machinery − has introduced the DNB/EL-1270 double needle bed warp knitting machine for making a wide range of fabric styles including technical, such as netting and high-performance ribbons and fabrics for a variety of industrial and technical applications; medical, such as tubular netting, disposable underwear and bandages and dressings; and apparel, such as fashion fabrics, and mesh pantyhose and stockings. The machine has a 1, 270-millimeter working width, features individual latch needles and is compatible with any yarn. Five to 18 needles-per-inch gauges are offered; and the DNB/EL-1270 comes with 12 electronically-controlled pattern guide bars, allowing different weaves to be created without stopping the machine. Knockover sinker groups are available if specified. Thread feeders are electronically controlled, allowing varying stitch density, and differing weft and warp feeding. The DNB/EL-1270 can be fed by creels or beams, or a combination of both. The machine will accept floor-standing external electronic yarn feeders, or electronic yarn feeders can be attached to the machine. Finished product collection systems can be tailored to each customer's specific requirements. Comez's new Data Control Controller manages all machine functions, monitors production and allows large pattern repeats to be created. Using two needle beds and the pattern guide bars, the machine can produce double-faced fabrics. Depending on parameter settings, the two sides can be differentiated by using different structures or yarns; or, the front and back of the fabric can be made to look identical. Spacer fabrics, which are highly suitable for technical end-uses, also are possible. Rigid and elastic products can be created in flat or tubular configurations to form netting-type products that range from simple open structures to more complex structures.