The adulterations of wool are more serious than those of cotton. The excellent qualities of wool, its warmth, its ability to keep its shape and smoothness through long wearing, the richness of material made from it, the ease with which it absorbs and retains dyes, all contribute to create the immense demand for woolen cloth. At the present time this demand so far exceeds the supply that one-third of the woolen cloth on the market is made from old rags worked back into fiber and respun. This made-over wool, or shoddy, appears in various forms. It may be quite good in quality and be woven into woolen cloth without the addition of new wool. A small quantity of new wool or of cotton may be mixed with shoddy, when a better wearing material will be the result. Short fibers, either shoddy or the clippings from tailors' shops, sweepings from looms, etc., may be matted into the surface of cloth to add weight and thickness. This treatment may often be detected by raveling threads from the cloth, when the very short fibers drop out. Shoddy supplies a cheap wool, with good warmth, but does not look as rich as a more expensive cloth or wear as long-as new wool. The threads from a piece of shoddy break easily, and when raveled the short fibers are exposed. Under the microscope broken and imperfect fibers may be detected, as well as unevenness in size of thread and in color.
Fig. 35. Cloth Made from Shoddy and Cotton.
The use of cotton to adulterate wool is very common, and because of the felting property of wool much cotton may be concealed in a woolen cloth. In worsted cotton is more easy to detect, as it may not be carded with the wool, but a spun thread of cotton can be mixed with a spun thread of wool. Burning serves to distinguish cotton from wool, although this is not an exact test. Cotton burns much more quickly than wool and with more flame; wool has an odor of burnt feathers, chars, and leaves a crisp ash. The broken end of a wool thread shows fibers stiffer and more kinky than the broken end of a cotton thread. Here the microscopic test is most satisfactory.
In some materials the mixture of cotton and wool is a good one. Especially is this true in undergarments, when the cotton comes next to the body, absorbs the moisture quickly, and gives it up gradually to the wool outside. The manufacturer, however, is not always willing to say that his undergarments contain cotton. "Wool" union suits have been found with varying amounts of cotton, from about ten per cent to perhaps ninety per cent, and some "all-wool" garments are really all wool. In dress material the greatest objection to the mixture of wool and cotton is the uneven shrinkage of the two, which makes it impossible to keep the material well pressed. There are exceptions to this in mohair and alpaca, where the wool is much more hair-like and does not shrink and felt as sheep's wool does. In this case the cotton is not considered an adulteration, as the material is not sold for all-wool and does not command a high price. Poor grades of wool are disappointing in that they soon wear shabby, shrink badly when wet because of lack of proper shrinkage in making, and lack fastness of color.
A. Imitation Dotted Swiss, Paste Dots Printed On.
B. Same after Washing a Few Times.
C. Pressed with Hot Iron.
Fig. 34. A. Imitation Dotted Swiss, Paste Dots Printed On B. Same after Washing a Few Times C. Pressed with Hot Iron.
Fig. 37. Mohair, Showing Cotton Warp; Wool Removed by Caustic Potash.
There are many grades of woolen and worsted cloth, varying in weight, firmness of weave, finish, purity, color, weave design, etc. The standard broadcloths, worsted suitings, expensive voiles, etc., materials which bring a good price, are usually all wool and wear well. Here again the "novelty," the new material for the season, not always the lower-priced cloth, though frequently so, is the one to be examined. Unfortunately, the poor-grade cloth usually sells at the price which catches the buyer who can least afford to be deceived and to whom economic waste is most serious.
Since silk is the most expensive fiber and has characteristics which make it very easy to adulterate, the manufacturer frequently yields to the temptation offered him. The best grade of silk, that reeled from the cocoon in one continuous thread, possesses a high luster, beauty, and strength not to be duplicated. Silk carded and spun from inferior cocoons lacks the luster and strength of reeled silk, but may be used in combination with it to produce excellent materials. This inferior silk is frequently used for the back of velvet and satin and for the warp of silk woven with the sateen weave, when the luster is produced by the filling thread. The thread of spun silk is quite like cotton. It has short fibers whose ends appear fuzzy on the surface of the thread. Poorer qualities of silk, imitation pongee, and some thin, cheap silks are woven entirely of spun silk.
Two generations ago the quality of silk cloth was much superior to that now found upon the market, but the price was also much higher. The public has demanded silk for common use at a low price, and the manufacturer has met this demand by using less silk in a given material and making up the weight by increased amounts of dye, metallic salts, gum, etc., which the silk fiber readily absorbs. This loading process reduces the wearing quality of the fiber and often causes it to split or to wear shiny. Practically no silk can be found entirely free from loading, but the amount differs greatly in different materials. It is considered legitimate to add thirty per cent, the equivalent of the loss due to the removal of silk gum in the boiling-off processes. Taffeta is commonly heavily loaded, while China silks and other thin silks, as crepe de Chine and chiffons, which weigh only a few ounces per yard, are comparatively pure. Softness and luster do not serve to distinguish pure silk, as a lustrous finish may be given to a heavily loaded silk.
The simplest test for weighting consists in burning a thread or a piece of the fabric. Pure silk burns slowly, leaving as it burns a small amount of ash in the form of a crisp ball at the end of the thread or a crisp edge when the fabric is burned. Heavily weighted silk burns leaving the ash in the form of the original thread or cloth; this ash, of course, drops to pieces readily.
The cost of raw silk is about thirty times that of raw cotton, and the loss of silk at least five times that of cotton. The prices charged for silk fabrics are not at all equivalent to this difference. Silk is frequently woven with cotton, but it is not possible to spin a thread of the two together. In satins, velvets, and brocades the cotton forms the back of the cloth, and is entirely covered by the silk threads on the surface. In cheap silks a fine cotton thread sometimes forms either warp or filling. Mercerized cotton and spun silk are woven together to form a material which resembles pongee, and is sold under the names of rajah and tussah, or similar materials may be made entirely of mercerized cotton.
Fig. 38. A. Sample of Silk.
B. Same Burned in Flame.
C. Ash after Thorough Combustion.
Gave test for tin, aluminum, chromium, and iron; this with glucose gums, etc., made up 60 per cent of sample.
Such materials may be excellent in themselves and may wear well, but they should not be sold as good silks.
•The variety of silks on the market is very great, and the problem in buying them is a difficult one. To a certain extent cost is a protection, yet expensive silk may be poor. Heavy silks at a low price are a dangerous investment. The mark of the manufacturer in the selvage of silk is a good sign, as a manufacturer does not often flaunt his label upon a poor material.