Silk Processing at Cheney Brothers in 1916
By 1916, Cheney Brothers had introduced so many innovations in silk processing that standard procedure was unrecognizable to people in the traditional industry. They were the greatest silk processor in the greatest silk processing country. These processes are so interesting and so characteristic of the revolution from the ancient Chinese methods that it bears mentioning.
The Waste Silk Much of the raw stock comes in as waste silk rather than reeled raw silk, and the first requirement is to bring this to the point already reached by reeled silk, or in other words, to spin it into yarn. Pierced cocoons arrive in the factory in large bales. These pierced cocoons and frisons, or outer covering, are boiled in soap solution and extracted to remove water by centrifugal force. Chemical agents, rotting, and maceration may also be used to remove the gum and loosen the filaments.
The Dressing Room In the dressing mill the cocoons are opened by being fed through rollers against a revolving cylinder, studded with innumerable wire hackles or needles, which pull the fibers into sheets or laps. These sheets and the frisons, which have been similarly pulled out, are run through a picking machine which still further draws out the sheet and cuts the sheet into nine-inch lengths, which the machine itself hangs like flags over small rods. These rods are put into a dressing machine with revolving drums covered with teeth, where the silk is combed and cleaned from much of its dirt and any remains of the chrysalis which have clung to it. The flags of silk are carried to a machine, which divides them into four or five short laps. The silk is then inspected and cleaned by being placed over long glass tables with light shining through from below. The laps are run together into longer laps measuring from seven to nine feet, and weighing possibly 4 ½ ounces. They are now ready to go to the spinning mill.
Spinning the Waste Silk In the spinning mill, the lap is drawn out into what is called a sliver, approximately the size of a finger, by running through rollers of draw frames, the second turning considerably faster than the first. In order to get the fibers even, several of these slivers, after being combed, are drawn out again into another sliver, and the process is repeated several times. The sliver is now taken to a drawing frame where it is wound onto bobbins, where it begins to look like a thread. It receives a partial twist. Now it is known as a single and may be used in this form. Cleaning is performed in the gassing room. The thread passes through several flames of gas, which singe off protruding fuzz. The thread passes too rapidly to be burned. The remaining charred fuzz is removed by running around small cylinders and breaks off.
The thread, in order to be made uniform, now goes to the controlling room, where many threads are run through the controller at once for the removal of knots. The yarn is then taken to the Grant reel where it is wound off onto a skein; the threads are criss-crossed, that after they cross, they will not tangle. These skeins of silk weigh from four to five ounces. After being inspected they are bundled up and sent to the warehouse where they may be sold as is, sent to the dye house to be dyed or the weaving mill to be woven un-dyed into goods.
Throwing the Reeled Silk The reeled silk must be carefully distinguished from the spun silk. The reeled silk “single” or the raw silk goes to what has long been termed the throwing mill. Throwing is taken from an old Anglo-Saxon word “thrawn,” meaning to twist, and the purpose of the mill is to twist, double, twist and combine again as often as necessary to produce the thread desired. Although this sounds comparatively simple, it should be remembered that it took several centuries before the English learned to throw silk well enough to compete with the Italians.
The skeins of reeled silk are put on a light skeleton reel, called a swift, which can be changed in size to fit various skeins. The silk is wound off this reel upon a bobbin simply by the friction caused by turning of a lead cylinder against the bobbin, – a method which, as already mentioned, avoids breaking the threads. The reeled silk is often cleaned at this stage by running it between carefully set knives.
The principle of twisting consists of running a horizontal bobbin off on a vertical one that turns at a faster speed. The yarn runs through the eye of a little metal flyer on the top of the first bobbin, and the difference in speed between the two bobbins regulates the amount of twist. Singles are sometimes given 60 twists to the inch. The doubling is done by running the two threads together through the single eye of a guiding bar onto another bobbin. It is very important to have the machine stop if a thread breaks. Before they are joined, each thread holds up one end of a separate lever that acts as a stop motion. If either thread breaks, the lever falls and stop the twister. After doubling, the thread may again be twisted – in the case of orgazine, in the opposite direction (one S-twist and one Z-twist). The twist may be set by steaming. The Cheney mills run some 30,000 spindles in the throwing department and 8,000 more in winding and spooling.
Trade Terminology Before leaving the subject of yarn or thread there are a few trade usages or terms that need explaining. Spun silk is numbered either on the English or French system. On the English system the number of 840-yard hanks required to weigh pound avoirdupois is the number of the yarn, while a sub-number tells whether the yarn is single or plied. Thus the number 50-2 is a two-cord yarn requiring 50 840-yard hanks or 42,000 yards for a pound. On the French system the number of thousands of meters of a single thread required to weigh a kilogram designates the number of the yarn, while the smaller number tells the number of threads. A 100,000 meter length that weighs 1 kilogram is a 100 and a two-ply weighs twice as much as the same number single. Thus 2-100 is made of two number 100 singles, and runs 50,000 meters per kilogram. (Note: In modern terms this is the denier system.)
Raw silk singles with the gum still on them are often used as warp for goods which are not dyed until woven. In yarn-dyed goods the usual warp is orgazine, which consists of two or more raw silk threads well twisted, both in the singles and after doubling.
The weft and filling of both yarn-dyed and piece-dyed goods is commonly called tram, and consists of two or more raw silk threads scarcely twisted at all before doubling, and generally only slightly twisted after doubling. For crepe or chiffon, however, the yarn used is a tram that is given a very hard twist, from 40 to 80 turns an inch. Floss silk generally consists of a large number of singles very slightly twisted. It is not used in weaving. Embroidery silk consists of a large number of slackly twisted singles, doubled and again slightly twisted in the reverse direction.
Hand-sewing silk is made by winding and doubling and twisting again in the reverse direction under strong tension.
Machine twist is made in a similar way, except that it has a three-ply, instead of a two-ply thread.
Source: Manchester, H. H., The Story of Silk and Cheney Silk, Cheney Brothers, South Manchester, Connecticut, 1916.