silk twisting

from the single ply of raw silk to twisted yarn in all shape

Torcitura di Dolzago is expert in the processing and twisting of Raw Silk.

Through specific processing, carried on particular machinery, the raw silk yarn in skein is treated so that it can be used in the following stages such as: weaving, knitting, dyeing.

In particular, the whole productive process can be divided in 10 different stages.

Test

Keisokki CLASSIFAULT

Each lot of raw silk skein, whether they are in purchase or processed on behalf of third parties, are tested and classified by means of a Japanese laboratory machine called KEISOKKI CLASSIFAULT. From each lot of 600kg of raw silk, a significative sample is picked up for the test. After being oiled soaked and rewound, the yarn is coned on the machine and passed through four sensors which analyse and register its qualities and possible defects, allowing a precise and thorough classification. In over ten years, we built a database containing data of over 3.000 lots of raw silk (over 2 million kgs) from most of the Chinese reeling mills and more. For this reason, we have a huge experience, indispensable for controlling and grading all the productions of the most important silk producers. In this way, we are able to classify each lot even before the start of the following processing, in order to control the quality of the yarn that is going to be produced.

oil soaking

of the raw silk in hanks

Currently, the raw silk under production is almost exclusively of Chinese origin. Each lot consists of packages containing 24/28 skein weighing 180/200 grams each, for a total of 5 kg. In order to be used in the following processes, silk has to be soaked adding a specific percentage of oil. In the silk soaking machine, the skeins are put in a specific tub, in which the vacuum is made. In this way, when the specific compound of natural origin is introduced in the tub, it permeates evenly on the skeins, granting a perfect distribution. The batch is obtained mixing tepid water and the “soaking oil”, a total organic compound (GOTS certificate) made from oils, fats and softeners. Sometimes a temporary fleeting tint is added to the mixture, it is also called fake-color and it is useful to distinguish different lots or yarn types. It is very important that the soaking oil used during this process does not damage the silk’s dynamometric properties with either an alkaline or rancidity reaction. The correct mixage of oil and water is mostly determined by the prefixed goal: opening the threads inner structure or better fix the twists. When the skeins are removed from the tub, they are hanged on specific trolleys, where they slowly dry, in order to preserve all the chemical and physical properties of the silk.

unwinding

the raw silk skeins

The unwinding is the first step of the mechanical processes of the production. It precedes all the other phases. After the skeins are dried, they are put in perforated baskets, are unwinded and rewound on flanged spools. The unwinding machines are positioned in air-conditioned rooms, so that the silk can be processed in the correct temperature-humidity-controlled environment. The workers assigned to this process look after the silk throughout the whole process, loading the skeins on the machines and knotting any broken thread in order to minimize the waste. In this phase the yarn is single an thin, the size is often only 20/22 denier. Neither machinery nor artificial intelligence can replicate the manual gestures perfectioned through the years of experience and dedication.

doubling

The silk yarn coming from first-rewound bobbins are combined with other yarns of the same nature to obtain the desired size by the doubling machines. The yarns can be either single ply raw silk for twisted yarns like tram and crepe or already twisted for yarns like organzine. For this process to be correctly executed, it needs a double control: the constant tension of each thread, to avoid producing a defective yarn, and the presence of all the required number of ends.

twisting

of silk

At this point the assembled yarn is put on the twisting machines to be twisted on itself as many times as its required for that particular type that must be produced. Torsion is measured in TPM, turns per meter, and ranges from 300 to 3000.

In this way, we are able to emphasize different qualities such as: brightness, opacity, softness, creping, resistance, smoothness etc.

Depending on which kind of yarn has to be produced, the final torsion can be given both before and after the assembling. Sometimes it can also be assembled and twisted more than once. Most important parameters in twisting are the spindle speed, the tension and the way the yarn is collected on the bobbins, all to avoid the production of a defective yarn.

steaming

At the end of the twisting operation, the torsion must be “fixed”, to avoid the formation of buttonholes. This is particularly important for those yarns with a very high torsion. This step of the producing process is called steaming or torsion fixing and is performed by putting the yarn bobbins in an automatic steamer in which all the parameters (temperature, time, vacuum etc.) are completely computerized.

final winding

of yarn

Le bobinage est la dernière opération du cycle de production, dans cette phase, le fil est reconditionné sur des bobines cylindriques de taille individuelle, prêt à être utilisé par le client final. Nous pouvons fournir tous les fils conditionnés à la fois sur des os pleins et sur des cônes perforés (grilles) pour la teinture.

Afin d'assurer la meilleure qualité possible, le fil passe dans des dispositifs appelés « Electronic clearers » (purgeurs electoniques) qui permettent à l'opérateur d'éliminer toutes les imperfections présentes sur le fil, qu'elles proviennent de la matière première ou qu'elles surviennent lors des différentes étapes de transformation. De cette manière, nous pouvons garantir au client la fourniture de fils fiables et de haute qualité.

sorting and delivery

At the end of the productive process, all the bobbins of finished yarn pass through a thorough checking, verifying that all the required quality standards, such as dimensions, weight, hardness, color uniformity etc., are met. At this stage the bobbins which passed the last exam, are packaged in a shrink plastic bag or in a polyester sock (for the dyeing process). At the end, they are closed in boxes, weighed and labeled, ready to be shipped.

silk winding

in hanks

For some particular lots of twisted silk yarn, it is necessary to pack them in hanks. The yarn packaged in this way is required to be used for the traditional hank yarn-dyed process.

conclusions

The entire process allows to produce many varieties of yarns, such as raw silk on cones, crepe, organzine, silk sewing thread, tram, silk pile etc. Starting from the single thread of 20/22 (or the other available counts size), it is possible to get up to 16/24/36/48 end and more, when required. In this way, we can satisfy all the possible requests of the always evolving textile industry.

Our production’s final destination is mostly the high fashion and high-end accessory worlds, but it is also present in the textile furniture, sportswear, underwear, technical articles and, in general, wherever is required the presence of the undisputed queen of natural fibers: silk. It is not only the story of a family, but it is the story of many generations of people who, for thousands of years, have been fascinated by this bright and strong filament, made by a little bug, son of a small butterfly. This is at the same time touching and extraordinary.