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The silk fiber is the most perfect as well as the most beautiful of all fibers. It is nearly faultless, fine and continuous, often measuring from 1000 to 4000 feet long, without a scale, joint, or a blemish, though not of the same diameter or fineness throughout its entire length, as it becomes finer as the interior of the cocoon is approached. Silk differs from all other vegetable or animal fibers by being devoid of all cellular structure.

Where Produced

Southern Europe leads in the silk worm culture—Italy, southern France, and Turkey, with China and India. Several species of moths, natives of India, China, and Japan, produce the wild silk. The most important of the "wild silks" are the Tussah. Silk plush and the coarser varieties of buff colored fabrics are made of this silk. While manufacturers do not favor the wild silk, the coarse uneven weave and softness make it a favorite with artists and it is being used for interior decoration as well as for clothing.

Silk Worm

The silk of commerce begins with an egg no bigger than a mustard seed, out of which comes a diminutive caterpillar, which is kept in a frame and fed upon mulberry leaves. When the caterpillars are full grown, they climb upon twigs placed for them and begin to spin or make the cocoon. The silk comes from two little orifices in the head in the form of a glutinous gum which hardens into a fine elastic fiber. With a motion of the head somewhat like the figure eight, the silk worm throws this thread around the body from head to tail until at last it is entirely enveloped. The body grows smaller and the thread grows finer until at last it has spun out most of the substance of the body and the task is done.

If left to itself, when the time came, the moth would eat its way out of the cocoon and ruin the fiber. A few of the best cocoons are saved for a new supply of caterpillars; the remainder are baked at a low heat which destroys the worm but preserves the silk. This now becomes the cocoon of commerce.

Reeling Silk

Next the cocoons go to the reelers who wind the filaments into the silk yarn that makes the raw material of our mills. The cocoons are thrown into warm water mixed with soap in order to dissolve the gum. The outer or coarser covering is brushed off down to the real silk and the end of the thread found. Four or five cocoons are wound together, the sticky fibers clinging to each other as they pass through the various guides and are wound as a single thread on the reels. The silk is dried and tied into hanks or skeins. As the thread unwinds from the cocoon, it becomes smaller, so other threads must be added.

SILK:—CATERPILLAR, COCOON, CHRYSALIS, MOTH

Organize and Tram

At the mill the raw silk goes to the "throwster" who twists the silk threads ready for the loom. These threads are of two kinds—"organize" or warp and "tram" or filling. The warp runs the long way of woven fabric or parallel with the selvage and it must be strong, elastic, and not easily parted by rubbing. To prepare the warp, two threads of raw silk are slightly twisted. Twist is always put into yarn of any kind to increase its strength. These threads are united and twisted together and this makes a strong thread capable of withstanding any reasonable strain in the loom and it will not roughen. For the woof or tram which is carried across the woven cloth on the shuttle, the thread should be as loose and fluffy as possible. Several threads are put together, subjected to only a very slight twist—just enough to hold the threads together so they will lie evenly in the finished fabric.

Boiling Off

After the yarn leaves the spinners it is again run off on reels to be taken to the dye house. First the yarn is boiled off in soapy water to remove the remaining gum. Now the silk takes on its luster. Before it was dull like cotton. The silk is now finer and harder and is known as "souple."

Loading Silk

The silk fiber has a remarkable property of absorbing certain metallic salts, still retaining much of its luster. This process is known as "loading" or "weighting," and gives increased body and weight to the silk. Silk without weighting is known as "pure dye," of which there is little made, as such goods take too much silk.

REELING SILK

For the weighting of white or light colored silk goods, tin crystals (stanous chloride) are used and for dark shades and black, iron salts and tannin. By this means the original weight of the fiber may be increased three or four hundred per cent. This result is not attained, however, except through the weakening of the fiber.

Action of Common Salt

Common salt has a very curious action on weighted silk. It slowly weakens the fiber. A silk dress may be ruined by being splashed with salt water at the seashore. Most often holes appear after a dress comes back from the cleaners; these he may not be to blame for, as salt is abundant in nearly all the bodily secretions—tears, perspiration, urine.

Artificial Silk

Artificial silk is made by dissolving cellulose obtained from cotton. It is lacking in strength and water spoils all kinds manufactured at present.

Characteristics of Silk

Silk, like wool, has the property of absorbing considerable moisture without becoming perceptibly damp. Like wool and all the animal fibers, it is harmed by alkalis. The important physical properties of silk are its beautiful luster, strength, elasticity and the readiness with which it takes dyes. Silk combines well with other fibers, animal and vegetable.

Value of Raw Fibers

A comparison of the relative value of textile fibers may be seen from the following approximate prices:

Cotton—$.07 to $.14 per pound; loss in cleaning and bleaching 5 per cent.

Flax—$.12 to $.30 per pound; loss in cleaning and bleaching about 20 per cent.

Wool—$.15 to $.30 per pound; loss in scouring 20 to 60 per cent.

Raw Silk—$7.00 to $10.00 per pound; loss in "boiling off" about 30 per cent which is made up and much more by "loading."