Textiles Part 21

=Ramie.= Ramie or China gra.s.s is a soft, silky, and extremely strong fiber. It grows in southwestern Asia, is cultivated commercially in China, Formosa, and j.a.pan, and is a fiber of increasing importance.

Ramie is a member of the nettle family and attains a height of from four to eight feet. After the stalks are cleaned of a gummy substance, insoluble in water, it is known as China gra.s.s, and is used in China for summer clothing. In Europe and America by the use of modern machinery and chemical processes the fiber is cleaned effectively and cheaply. After it is bleached and combed it makes a fine silky fiber, one-half the weight of linen, and three times stronger than hemp. It is used in Europe to make fabrics that resemble silk, and is also used in making underwear and velvets. With other fabrics it is employed as a filling for woolen warps. It will probably be used widely in the United States as soon as cheaper methods of cleaning are devised.

=Pineapple and Other Fibers.= Other fibers, of which that from the pineapple is the most important, are used for textile purposes in China, South America, parts of Africa, Mexico, and Central America.

Their use has not been extensive on account of high cost of production. The silk from the pineapple is very light and of excellent quality.

=Spun Gla.s.s.= When a gla.s.s rod is heated in a flame until perfectly soft it can be drawn out in the form of very fine threads which may be used in the production of handsome silky fabrics. Spun gla.s.s can be produced in colors; but on account of the low elasticity of these products, their practical value is small, though the threads are exceedingly uniform and have beautiful l.u.s.ter. Spun gla.s.s is used by chemists for filtering strong acid solutions.

A kind of gla.s.s wool is produced by drawing out to a capillary thread two gla.s.s rods of different degrees of hardness. On cooling they curl up, in consequence of the different construction of the two const.i.tuent threads.

=Metallic Threads.= Metallic threads have always been used for decorating, particularly in rich fabrics. Fine golden threads, as well as silver gilt threads, and silver threads and copper wire, have been used in many of the so-called Cyprian gold thread fabrics, so renowned for their beauty and permanence in the Middle Ages. These threads are now produced by covering flax or hemp threads with a gilt of fine texture.

=Slag Wool.= Slag wool is obtained by allowing molten slag (generally from iron) to run into a pan fitted with a steam injector which blows the slag into fibers. The fibers are cooled by running them through water, and the finished product is used as a packing material.

=Asbestos.= Asbestos is a silicate of magnesium and lime, containing in addition iron and aluminum. It is found in Savoy, the Pyrenees, Northern Italy, Canada, and some parts of the United States. Asbestos usually occurs in white or greenish gla.s.sy fibers, sometimes combined in a compact ma.s.s, and sometimes easily separable, elastic, and flexible. Canadian asbestos is almost pure white, and has long fibers.

Asbestos can be spun into fine thread and woven into rope or yarn, but as it is difficult to spin these fibers alone, they are generally mixed with a little cotton, which is afterwards disposed of by heating the finished fabric to incandescence. Because of its incombustible nature asbestos is used where high temperatures are necessary, as in the packing of steam joints, steam cylinders, hot parts of machines, and for fire curtains in theatres, hotels, etc. It is difficult to dye.

APPENDIX

=Testing Textile Fabrics.= This is an age of adulteration, and next to food there is probably no commodity that is adulterated as much as the clothing we wear. Large purchasers of textile fabrics and various administrative bodies, such as army clothing departments, railway companies, etc., have adopted definite specifications to ensure having good material and workmanship. Before the fabrics are accepted they are examined carefully by certain tests to see if they meet the requirements. Wholesale and retail merchants insist on various conditions when purchasing fabrics in order to conform to the increasing needs of the public. Hence every manufacturer, buyer, or dealer in fabrics should be familiar with the tests used to determine the quality of goods he is about to buy.

The tests used are as follows:

1. Identification of the style of weaving.

2. Testing the breaking strength and the elasticity by the dynamometer.

3. Determining the "count" of warp and filling.

4. Determining the shrinkage.

5. Testing the const.i.tuents of warp and of filling.

6. Testing the finish and dressing materials.

7. Testing the fastness of the dye.

=Directions for Determining the Style of Weave.= In examining a fabric for the weave it is first necessary to determine the direction of the warp and filling threads. This is a very simple matter in a great many fabrics that have a selvedge--the warp must be parallel to the selvedge.

In fabrics that have been fulled, raised, and cropped, as buckskin, flannel, etc., the direction of the nap will indicate the direction of the warp, since the nap runs in this direction.

In the case of fabrics with doubled and single threads, the doubled threads are always found in the warp.

In fabrics composed of cotton and woolen threads running in different directions, the cotton yarn usually forms the warp and the woolen yarn the filling. Then again the warp threads of all fabrics are more tightly twisted than the filling threads, and are separated at more regular intervals.

Sometimes in stiffened or starched goods threads running in only one direction can be seen. In this case they are the warp threads.

If one set of threads appears stiffer and straighter than the other, the former may be regarded as warp, while the rough and crooked threads are the filling. The yarn also gives one a hint, since the better, longer, and higher number material const.i.tutes the warp, while the thicker yarn the filling.

The direction of the twist of the thread is conclusive; if one set has a strong right twist and the other a left twist the first is the warp.

After determining the direction of the warp and filling, the next point is to determine the interlacing of the warp and filling threads--the weave. This may be done by inspection or by means of a pick-gla.s.s and needle. The weave may be plotted on design paper (plotting paper), the projecting warp threads being indicated by filling up the corresponding square, and leaving those referring to the filling threads blank. In this way the weaving pattern of the sample is obtained, and serves as a guide to the weaver in making the fabric, as well as for the preparation of the pattern cards for the Jacquard loom.

=Testing the Strength and Elasticity of a Fabric.= The old-fashioned plan of testing cloth by tearing it by the hand is unreliable, because tearing frequently requires only a certain skilled knack whereby the best material can be pulled in two. In this way an experienced man may tell good from bad cloth, but he cannot determine slight differences in quality, because he has exerted his strength so often that his capacity to distinguish the actual force has disappeared.

The best means of determining the strength of a fabric is by means of a mechanical dynamometer,[19] which expresses the tensile strength of the fabric in terms of weight. The machine is very useful to the manufacturer because it enables him to compare accurately his various products with those of his compet.i.tors. The value of these tests is sufficiently proved by the fact that all army clothing departments, etc., require their supplies of cloth, etc., to pa.s.s a definite test for strength.

Breaking tests also afford the most certain proof to bleachers of cotton and linen goods as to whether the bleaching has burned or weakened the goods. The same test will quickly determine whether a fabric has been improperly treated in the laundry.

=Determining the Count of Warp and Filling Threads.= Every fabric must contain a certain count of warp and filling threads--a definite number within a certain s.p.a.ce for each strength of yarn employed. A fabric is not up to the standard of density when less than the requisite number of warp or filling threads per inch is found. For example, if a buyer was told that a fabric is 80 square, that is, eighty warp threads and eighty filling threads to the inch, and on examination found only 72 square, he would immediately reject the goods.

The count of warp and filling is determined by means of a pick-gla.s.s--a small mounted magnifying gla.s.s--the base of which contains an opening of one-half inch by one quarter inch, or one quarter inch by one quarter inch. If the pick-gla.s.s is placed on the fabric the number of warp and filling threads may be counted, and the result multiplied by either two or four, so as to give the number of threads to the inch. For example, if I count twenty picks and twenty threads on a one quarter-inch edge, there are eighty picks and eighty threads to the inch. A more accurate result can be obtained by using a pick-gla.s.s with a one-inch opening.

=Determination of Shrinkage.= A very important factor in the value of a fabric is the shrinkage. The extent of this may be determined by pouring hot water over a sample of about twelve by twenty inches, and leaving the fabric immersed over night, then drying it at a moderate temperature without stretching. The difference in length gives the shrinkage, which is usually expressed in percentage.

=Determination of Weight.= Buyers and sellers of dry goods, when traveling, are anxious to determine the weight of fabrics they examine. This may be done by means of small pocket balances so constructed as to give the number of ounces to the yard of a fabric.

=Testing the Const.i.tuents of the Warp and Filling.= Take a sample piece of the cloth to be examined--the piece must be large enough to contain specimens of all the different kinds of yarn present in the material--and separate all the filling and warp threads. Be sure that all double threads are untwisted.

=Combustion Test; Test for Vegetable and Animal Fibers.= Burn separately a sample of the untwisted warp and filling threads. If one or both burn quickly without a greasy odor, they are vegetable fibers, cotton or linen. If one or both burn slowly and give off a greasy odor, they are animal fibers, wool or silk. This test is not conclusive, and further chemical examination--acid test--must be made to ascertain whether wool is pure or mixed with cotton.

=Acid Test.= The vegetable fibers, cotton and linen, are distinguished from those of animal origin by their behavior in the presence of acids and alkalies. The vegetable are insoluble when boiled with a 4 per cent sodium hydrate solution, but readily clear or carbonize when saturated with a 3 per cent sulphuric acid solution and allowed to dry at a high temperature in a hot closet. Wool on the other hand is not affected by the action of weak sulphuric acid.

=Cotton Distinguished from Linen.= If the fibers are vegetable, cotton may be distinguished from linen by staining the fibers with fuchsine.

If the fibers turn red, and this coloration disappears on the addition of ammonia, they are cotton, if the red color remains the fibers are linen. Whenever cotton yarn is used to adulterate other fabrics, it wears shabby and loses its brightness. When it is used to adulterate linen, it becomes fuzzy through wear. One may detect it in linen by rolling the goods between thumb and finger. Linen is a heavier fabric, and wrinkles much more readily than cotton. It wears better, and has an exquisite freshness that is not noticed in cotton fabrics.

=Silk Distinguished from Wool.= Place the fabric or threads containing animal fibers in cold, concentrated hydrochloric acid. If silk is present it will dissolve, while wool merely swells.

=Artificial Silk from Silk.= On account of the low value of the artificial and the high value of genuine silk, there is a tendency to offer the artificial instead of the pure article. Test: When artificial silk is boiled in 4 per cent pota.s.sium hydrate solution it produces a yellow solution, while pure silk gives a colorless solution.

A common test is to put the artificial silk in water, where it will pull apart as though rotten; or to take out one strand of the silk, hold it between the finger and thumb of each hand and wet the middle of the strand with the tongue, when it will pull apart as though rotten.

Artificial silk is inferior in strength and elasticity to pure silk.

Then again it is lacking in the crackling feeling noticed in handling the genuine article.

=Test for Shoddy.= It is no easy matter to detect shoddy in woolen fabrics; the color of the shoddy threads is the best evidence. Many parcels of rags are of one single color, but for the most part they are made of various colored wools; therefore, if on examination of a fabric with a magnifying gla.s.s a yarn of any particular color is found to contain a number of individual fibers of glaring colors, the presence of shoddy can be a.s.sumed with certainty.

Woolen goods containing cotton are seldom made from natural wool.

Shoddy yarns, especially in winter goods, are found in the under-filling at the reverse side of the cloth, as thick, tightly twisted yarns, curlier than those from the pure wool.

=Determination of the Dressing.= During the various operations of washing, bleaching, etc., the goods lose in weight, and to make up this deficit a moderate amount of dressing or loading is employed.

Dressing is not regarded as an adulteration, but as an embellishment.

Various dressing materials are used, such as starch, flour, mineral matters, to give the goods stiffness and feel on one hand, and on the other to conceal defects in the cloth, and to give a solid appearance to goods of open texture. The mineral substances used serve chiefly for filling and weighting, and necessitate the employment of a certain quant.i.ty of starch, etc. In order that the latter may not render the cloth too stiff and hard, further additions of some emollient, such as glycerine, oils, etc., are necessary.

When a fabric filled in this manner is placed in water and rubbed between the hands, the dressing is removed, and the quant.i.ty employed can be easily determined.