The spun-silk industry
The traveller who covered Vivarais country was struck to meet in the heart of the steep valleys, rosaries of small firms, which he hesitated to call factories. The small torrent channelled before every building was enough formerly to drive all the paddle wheels: sometimes the wheels of flour mills, but much more frequently those of silk mills.
Settled in the region in the XVI-th century, they had considerably developed afterward whereas "magnaneries" prospered in the south-east of France and whereas Lyons conquered of high fight the place envied of silk capital. Then about ten departments counted "milling" by 1945, of which in the lead Ardèche, Drôme, haute Loire …
As for mills they are little by little modernised. But really, what this industry of milling very few known from the general public, maybe because, intermediary between the threads manufacture and those of clothes, it does not offer it any manufactured product directly useful?
Spun-silk industry is the industry, which takes the raw silk threads in the end of the spinning, and transforms them into worked threads appropriate to fill the various uses for which are asking the user industries. These processing concern the thickness of the threads, their resistance, their elasticity, their touch, their aspect, their covering power, etc. … In fact the majority of the used threads must undergo milling operations.
In 1943, the French milling counted 348 factories in which 10.000 persons were working. Some milling workers spun-silk worker worked materials which belonged to them and sold the worked threads, but the majority worked in way for their customers.
The worked threads, result of the infinite combinations of twisting and assemblies, allow to obtain all the wished ranges of clothes. They are called weft, crepe, voile, organzine, grenadine, curled thread, buttoned, etc. …
The spun-silk technique is simple in its principle but contains uncountable difficulties of detail, which require all the science of the technicians and the workers to be surmounted.
Arriving at the mill the thread of raw silk resulting from the spinning has to undergo preparatory treatments. The raw silk is formed with a certain number of elementary threads welded together by the coagulated raw. It could be weaved but it is incapable to withstand the operations of dyeing in fleets. These handlings require the immersion of the silk in baths where the temperature reaches 100 °C. Under the influence of such a treatment, the gummy substance losing its consistency, being even able to dissolve, the elementary threads would tend to part one from the others, to form curls and knots. It would be impossible then to subject them to the weaving.
To give to the raw silk more resistance and to transform it into a thread able to withstand as good as possible the different handlings which are imposed before being transformed into clothes, one subjects to the spun-silk industry called also "working" .
One gives it a series of mechanical finish treatment consisting in twistings and twinnings.
The spun-silk industry includes 4 operations:
1. Unwinding of the raw silk hanks, to put it on reels.
2. Twisting given separately to every thread of raw silk resulting from reels
3. Twinning of 2 threads obtained, twisting and new unwinding on reel.
4. Forming, by a new twisting, of the threads resulting from the assembly of 2 or several threads of raw silk, unwinding on skein winder and put in hank.
The twisting of a single thread of raw silk is named "thread of first twist" and gives a thread called "Poil"
Two or several raw silk threads twisted together without being twisted first individually, give a thread called "Weft thread" Two or several raw silk threads twisted in advance and individually from right to left to whom one gives a twisting from left to right after having assembled them give a thread used generally for the warp and is called "Organsin".
But these ones are there the most widespread kinds of twisting, many other combinations are possible. The twisting is defined by the number of tours by meter. It is easy to conceive that by varying these individual or assembled twistings, their direction, their intensity, the order in which they succeed one another, it is possible to obtain threads of variable properties.
Twisting undergoes modifications in the physical properties of the silk:
The more a silk is twisted, the more its diameter decreases. At the same time the length and the shining decrease. Finally the resistance increases. To make clothes, the twistings must be chosen and be combined so as to give the most suited threads to the envisaged clothes.
In the XIV-th one uses in Italy a mill called round mill because of the shape, then in France appears the oval mill. These characteristics give special appearances to the cloth. The art of the silk manufacturer consists in a big part to determined what must be these types of twisting and assembly of the raw silk threads.
Originally, twistings were hand-made by processes similar to those that used rope makers. Here are more details of the operations undergo by raw silks in their arrival to the spun-silk industry:
First of all unwinding - which aims to clean the silk, to connect the broken threads, to remove ends and all disparities to obtain a thread as regular as possible. This causes a variable scrap according to the purity and the quality of the silk from 2 to 8 %, even 30 or 50 % when one treats very impure and pulled very roughly exotic silks. To be unwound, the fleets of raw silk are placed on skein winders turning vertically around an horizontal axis. Bobbins or reels, turning by friction roll up the silk and make turn the skein winders. Between skein winders and bobbins is interposed a movement of goes and comes alternate distributing the silk thread also on the bobbins. The curls of goes and comes were generally fitted with sheet on which the friction of the raw silk led to a first cleaning. When the silk is sound, it breaks rarely, supplies few stuffs and consequently few waste.
From the point of view of the unwinding, one estimated the quality of a raw silk , by the number of skein winders that a worker could watch simultaneously, for example 40 skein winders. The custom had become established for the sales of raw silk to indicate this number of skein winders. The best raw silks unwind in 100 skein winders with sometimes a scrap lower than 0.25 % (silk of ancient Cevennes). Unwinding, simple in the principle is very delicate and it is necessary to monitor the hygrometry and to be able to wet them or to grease with a solution of soap if necessary. Besides it is necessary to adjust in best way the speed of the unwinding. This summary cleaning is completed by the passage of the threads in stuffs cleaners. The previouly obtained bobbins by the first unwinding are again unwound. The thread is guided with a china or glass roulette and cross then 3 stuffs cleaners to go to wind on of new bobbins through a goes and comes. stuffs cleaners are formed with crowbars stocked with sheet, on which the thread, by rubbing, abandons the downs which it can contain. If a cork arises, the stuffs cleanersstops the thread so that the worker trouble shoots the defect. The stuffs cleaners in sheet presented the defect to lose their efficiency as the stuffs filled them. Different models more effective and adjustable in steel replaced them.
Finally cleaned by these two successive unwindings, the raw silk can receive various destinations: to form some weft, one doubles them before to send them to the mill which is in charge to twist them. For the organzine at first twisted in the mill, then twinned and twisted in the opposite direction. For the "poil", they undergo only a twisting. The twistings are given as we have seen it, by the round mill (Italian) or the oval mill (French) of which we shall not describe today the functioning (it will be the object of another article) but of which you will find below prints representing them.
Finally the worked, theads are supplied under shape of fleets or hanks. During a long time the length the worked threads was of 1500 metres. The silk fleets were "capiées", meaning that two extremities free of the fleet were gathered by a knot to a circular link in "schappe" or in cotton called "capiure" in the aim to avoid the trangling up. Afterward, the American system of the Grant fleets was adopted. The length the worked thread increase from 1.500 to 20.000 metres by a system of link no more circular but by intermittent overlapping separating so the big fleet in " under fleets ".
Knowing that any defect, any irregularity will be seen in the cloth, one understands how much the operation of spun-silk industry is major in the preparation of silk trades.
Conclusion: In our time, in public opinion, the silk clothes keep their reputation of luxury, quality, rarity and prestige. Nevertheless it is necessary to distrust, in thissubject, pernicious and noisy offers of the commercials which supply these clothes and these garnments. Everywhere, advanced criterion is that ether such or such material is in pure natural silk or silk 100 %. This means (at least if there is no deceit) that the chemical composition of the cloth is made really with pure silk. What does not prevent that there are strong chances whether it is a extremely inferior material. The origin of the silk is important (China, Japan, Brazil), knowing that the silk of Brazil is at present of better quality than the silk of China. But also the quality of the milling is crucial. The nature of the thread counts a lot because in all the levels of the textile industry chain (spinning , milling, weaving), wastes are recycled for example in "Bourette" of silk which is only constituted of the badly waste, of which the scrap of the waste recovery! (With waste one makes the silk "schappe" of, and with the waste of the manufacture of the "schappe", one makes the "bourette" of silk). And nevertheless it is indeed pure 100 % silk!!!
Finally, and not the least, care taken at the time of the weaving and not he quality of the silk thread but of the material itself: How many threads by centimetres (reduction)? Is it sufficient to give a cloth of quality, it means solid, with fabric hand and flowing? Is dyeing adapted, solid or botched? If you succeed in thwarting all these traps, then you will possess a qualitative material, solid, indestructible and prestigious. But there as evarywhere else, this has a cost and there is no miracle to be waited...
(Translation Gilbert Graveleine)