Wednesday, 28 December 2011

Twist in Silk

Silk yarn is classified in several ways based on the twist. A some of them are as follows:

Raw Silk
In this the silk is produced by reeling together baves of several cocoons. It has no twist.

Poil Yarn
A silk yarn produced by twisting raw silk. The twist may be slight or exceed 3000 per meter.

Tram Silk
To make a tram yarn, two or more raw silk threads are doubled and twisted slightly. Generally the twist is about 80 to 180 TPM ( Turns per meter)

This yarn is made by doubling several raw silk threads and twisting them to very high levels in the range of 2000 to 4000 TPM.

This silk yarn is formed by doubling two or more poil yarn and throwing them in a direction opposite to that of the individual yarn. The twist in the poil yarn will be about 700 TPM ‘Z’ and the doubled yarn will have about 950 TPM ‘S’.

Steaming of Twisted Yarn

The twisted yarn has to be subjected to steaming in an autoclave. This process fixes the twist in the thread. Duration of steaming depends upon the depth of layers of threads in the bobbin and twist levels of the thread. Ten minutes is usually sufficient for organza while more highly twisted crepe require considerably more time of about 2 hours. 

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Monday, 26 December 2011

Waste Products of Mulberrry and Tussar Silk

Mulberry Silk

-          Spun Yarn: Matka, Handspun- Spun by Takli, Milspun- By Mill process

-          Waste yarn: Dupion

-          Short fiber in spun: Noil

Tussar Silk

-          Spun Yarn: Muga: Milspun

-          Waste Yarn: Ghicha

-          Inside yarn: Katiya

Spun Silk Production

Spun Silk takes the following process route:

1. Degumming the silk waste: It is done in degumming vats.
2. Dryers for drying the degumming material.
3. Openers for opening the fibres.
4. Fillers for opening and cleaning the material.
5. Dressing machine is used for combing the materials neps and remove the foreign materials, neps and short fibre and make a lap with average steple length.
6. Spreader : To further make the fibers parallel. Set frames for obtaining sliver.
7. Draw frame is used for making the Sliver with fibres more perfectly paralised, blending also can be done by this machine.
8. Roving machine for making roving (standard of thread with little twist from silver).
9. Ring frame is used for making the spun yarn from roving and insert sufficient twist for strength and wind in a bobbin.
10. Winding & doubling machine are used for two or three fold commercial yarn.
11. Gassing is done for removing the protruding fibres by passing the yarn through the flame at a speed 500-600 mts/min.
12. Reeling to make standard sized hank.
13. Bundling & Balling : First make a bundle and bale for disposal of the material.

The size of spun silk thread is defined in a similar manner to standards used for cotton yarn. For cotton, the term "2/60s"signifies a two-ply yarn consisting of two single strands twisted together, each having a yearn count of 60.
In the case of spun silk the notation has a different meaning. For example, for 60/2 two yearns with a separate yarn count of 120 have been doubled, producing a ply yarn with a new count of 60. (Source)

Spinning of Tussar

 Tassar silk waste is degummed by boiling in a pressurised tank with soap and soda for 30 min and treated with sodium sulphite for partial bleaching. However, to remove gummy matter completely, the material is subsequently kept in a soap and soda solution in a large wooden tank for 3-4 days. After degumming the material is fresh water, hydro extracted and subsequently dried in hot air chambers. The degummed tassar waste is then processed through a series of operations which includes opening, filling, dressing or combing, spreading, drawing, gill roving, spinning and gassing. Mill spun tassar yarn in the range of 60-210s (metric count) can be produced. The yarn is then doubled and twisted according to the required specifications.(Source)

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Silk Reeling

Silk Reeling

In general silk reeling is defined as unwinding of silk cocoon. However it is technically defined as the process of finding the right end of the cocoon filament and jointly taking several ends together to reel raw silk. These processes are carried using reeling machines.

 Depending on the size of the yarn required to be produced, filament from the cocoons are drawn out simultaneously, compacted and wound on to a reel.  For example, if 20 / 22 denier yarn is required, filaments from 8 to 9 cocoons are drawn out simultaneously, compacted and wound.

Silk Reeling broadly has these operations:

a. Catching the correct number of threads to maintain the denier

This is done using a mechanism called Jettebout.

b. Intertwining of threads

This is done using a special mechanism called croissure. Croissure also squeezes most of the water contained in the filament. If the sericin is wet, the threads wound on the reel will stick to each other and defects like hand gum spots result.

c. Distribution of the yarn

 This is done using an arrangement called distributor or traverse.

d. Winding of the Yarn

This is done on reels

Quality of Water used in reeling

The water used for silk reeling should be free from impurities as many animal fibres like silk have a decided tendency to fix any substance found in water. Such water alters the appearance of the fibre as its luster becomes dull and matte, thus reducing the quality of the silk.

Reeling of Tusssar

Tassar reeling is not carried out in filature like mulberry cocoons. Mostly it is done in small quantities by the womenfolk of weaver’s family.

Lacing and Skeining

In this process the two ends of the silk hank are tied with coloured thread. Lacing is a process in which a thread passing across the hank in such a way so as to devide it into five equal parts. So that the threads are kept in place to ensure that the thread can be unwound easily. For differenciating different denier of silk different coloured threads are used.

It is done by twisting the hank several times and folding it upon itself in a number of spirals.

Book Making and Bailing

The skeins are made into neat books of approximately equal weight and dimensions in a bookmaking  machine. In each book there are eight skeins in the horizontal row and five in the vertical row.

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Sunday, 25 December 2011

FAQ about Silk Manufacturing

What is Raw Silk as termed commonly

When we talk about raw silk, we generally are talking about mulberry raw silk. It is the compact untwisted and undegummed silk thread that is formed by combining the required number of silk filaments drawn from as many separate cocoons by a special technique called Reeling.

What is Filature Silk

The building in which cocoons are reeled for the production of raw silk is called a filature.It is carried with
sophisticated automatic machines,to ensure production of raw silk of desired qualities. The filature concept is
seen in developed countries where the raw material (cocoons) are of superior quality.

What is the type of Silk used in Indian Villages

However, more than 50 per cent of silk is reeled by a villager using country charka which forms the cottage industry. In the group of natural fibres.

What is the percentage of Silk production of all Textile fibers in the world

Which comprises cotton, wool and silk, production of silk amounts for 0.3 per cent only.

What are the other uses of silk apart from garments and home furnishings

Silk yarn is used as A package material in pencil industry and for making talcum powder puffs. Silk is used as raw material for preparing sound-free gears for making precision machinery. In France 22-24 denier silk is used in tyre manufacturing to have a longer life span than rubber tyres. Parachutes are made from 13-15 denier silk fiber. The silk gut used in surgery for internal suturing is made from silk glands. The silk glands are dissected out and put in warm water and pulled at two ends to yield a fibre of uniform thickness. This protein is auto absorbable and need not be removed after wound healing. Silk grafts have been used successfully to replace cut arteries.

What type of production is more in India- Raw silk or Cotton waste

India is very poor producer of raw silk to meet international standards. In India raw silk production is overtaken by silk waste. India produces annually about 180 tonnes of spun silk yarn and 130 tonnes of noil yarn besides hand spun yarn.

Why Silk Reeling using Charkha is inferior

Silk reeling, using country charka is of low quality but it contributes more to the raw silk produce. The reasons
for low quality silk in country charka are as follows;

1. No sorting of cocoons. Defective cocoons are also reeled.
2. No cocoon mixing
3. Improper deflossing.
4. As there is no jettebout the dirt, gum spots etc., can be eliminated. However, the charka has Tharpatti but
cannot function like button or jettebout.

What are cocoons, what are they made up of


Cocoon is nothing but a protective shell made up of a continuos long protein silk filament spun by mature silkworm

Content Percentage

Fibroin 72.0-81.0
Sericin 19.0-28.0
Fat & Wax 0.5-1.0
Colouring matter & ash 1.0-1.4

What are important physical and commercial characteristics on which the production and quality of silk depends


Indian races produce either white or yellow cocoons and white cocoons have a slight edge over the yellow cocoons in market price.


For easy relling spherical, oval and moderately constricted or printed cocoons are selected.


The size is generally indicated by the number of cocoons per litre.Generally the number of cocoons per litre varies between 110 to 400. Uniform sized cocoons are required for reeling.

Hardness or Compactness

When a cocoon is lightly pressed between the fingers, it should not yield but should feel firm, compact and

Grain or Wrinkle

After deflossing the cocoon surface should be granual or wrinkled with convolution.For better reeling fine granular cocoons are selected.

Weight of Cocoon

Weight of Cocoon Shell 

Larger the weight of the shell, greater the silk yield.In Indian multivoltine hybrids the shell weights is 200 to
300 mg. , while it is 180 to 250 mg in multivoltine pure races. Indian univoltine cocoons have 200 and 300 mg of silk shell.

Commercial Chracteristics

1. Shell Ratio: It indicates the quality of raw silk that can be reeled from fresh cocoons. Shell ratio is the
weight of cocoon shell and weight of whole cocoon. . It varies from 12 to 19 per cent.

2. Length of filament

It denotes the length of silk in the cocoon. It varies from 300m to 1200 m.However non breakable filament length (NBFL) which is the average length of filament that can be unwound without breaks is very important.

3. Weight of reelable filament

The complete silk filament of the cocoon cannot be reeled. The outermost floss layer and innermost pelade layer cannot be reeled and therefore removed.

4. Denier

It determines the size of silk. The denier is high in outer floss layer than the middle or inner layer.The tolerance limits for the commercial raw silk are 13/15, 20/22 denier. Denier = ( Total weight of reeled silk in grams/Total length of reeled silk in meter) x 1000.

5. Raw Silk Percentage

This is the percentage of the quantity of raw silk reeled in relation to the quantity of fresh cocoons used for
reeling. This can vary from 40 to 85 per cent. Raw silk Weight = ( Wt of Reeled silk/wt of cocoon)x 100

6. Floss

It is the value outermost loose, fragmented unevenly thick silk layer of the cocoon. It is a waste silk.

7. Renditta

It is the value derived from liter of cocoons required to produce one unit (1 kg) of raw silk. It varies from 6 to
14. The lower the value, the better is the quality of Silk.

What are the various steps of Silk Manufacturing after the cocoon is ready and collected

The various steps are as follows

1. Cocoon Stifling and Conditioning
 The process of killing the pupa and keeping the cocoon in good condition by storing in a proper conditions is
called stifling and conditioning of cocoons.

a. Stifling of Cocoons
It can be done by
- Sun Drying
- Steam Stifling
- Hot Air Drying

Sun Drying
It is a method of killing and drying the pupae by prolonged exposure of freshly harvested cocoons to hot sun. It is simple and cheap and drying is even/uniform. However, it is not suitable for modern reeling, can only be done on bright days, prolonged exposure can cause poor quality silk, increases wastages of silk reeling, involve space and labour and the cocoons can get dust and dirt in the process. Tussar in India uses sun drying method.

Steam Stifling
In this process, the fresh cocoons are exposed to hot wet steam, for a required period. Large quantity of cocoons can be stifled in a short time. However, it kills the pupa inside and doesnt dry it properly. There is also a problem of mould formation and leaking of body fluids of pupa onto silk. It also affect the sericin, increasing silk waste.

Hot Air Drying
In this the pupae are killed by exposure to hot air. It is the best method of stifling, giving good quality of silk
and dried pupae.

2. Cocoon Storage
After complete drying, the cocoons are to be stored in a store house which is protected from rats and is moisture proof.To protect the cocoons from fungal attack, the inside temperature and relative humidity of the store need to be maintained at 27 deg C to 30 deg C with 60-70 per cent relative humidity.

3. Cocoon Sorting
Sorting of Cocoon is done before reeling to give good quality cocoons.

4. Deflossing
Generally deflossing is done by fingers but now simple hand operated machines are also available.

5. Riddling

It is a process that separates the cocoons according to their sizes.

6. Cocoon Cooking and Brushing.

Silk thread spun by silkworms is technically called as ‘bave’. This is a composite structure which inturn has two filaments inside which are known as ‘brins’. Brins are the filaments which are produced by the two silk glands. Brins are made up of silk protein biborin synthesized in the silkglands. The brins are intrun bound by silk protein called sericin.

The cooking process is done for softening the sericin to facilitate easy unwinding of the silk filament at the same time.The sericin content of the silk filament ranges from 25 to 30 per cent, which varies in different races. In cooking process 7 to 8 per cent of sericin is dissolved.

 In order to cook the cocoons properly there are different types of systems of cooking.

1. Top reeling or floating system
2. Sunken system

In top reeling the cocoon shell becomes wet and impervious to water and float in water when the cooked cocoons are put in to the reeling basin. In sunken system the shell is cooked and the process fills the cocoon with water (97- 98 per cent) and makes the cocoon heavy and which sink in the reeling water. The top reeling is a old method while sunken reeling is a latest method.

Traditionally tassar cocoons are cooked in an earthen pot at or near boiling sodium carbonate (washer man’s soda) solution for 4-6 hours. Cocoons are then reeled in semi moist condition on Natwa/Thigh, where the productivity per day per reeler comes to about 60-80 g of 60 D silk yarn.

The cocoons have to be brushed to remove the surface floss before reeling. Floss is a lossely knit, broken, uneven thickness, water silk. Without removing the floss layer one cannot reel the proper silk. This waste layer obstructs the reeling process unless it is clearly removed. The process of removing floss layer is called “brushing”.Brushing can be done with the help of a stick, a brush or through mechanical means.

---to be continued---

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Tuesday, 20 December 2011

Comparing Silk Fabrics from China and India

The following are the major differences between Silk Fabrics made from China and India.

1.    The raw silk produced by Chinese producers is qualitatively better because they employ dried cocoon reeling method as compared to the Indian silk producers who employ fresh cocoon reeling method to obtain raw silk.

2.   Majority of Indian silkworms are multi-voltine variety, whereas Chinese silkworms are of the bi-voltine variety, which has high productivity of cocoon per acre, and the cocoon has higher silk output per kg, and the silk has higher tensile strength on the loom.

3.    The machinery used by the Indian producers are obsolete, simple and inefficient which is the primary cause for the higher per unit value of Indian silk as compared to Chinese silk.

4.    The twisting machines used  by Indian producers to produce silk yarn can reach 800 twists per minute at the most. However, the twisting machines used by Chinese producers are advanced and can reach a number of twists of more than 2600 twists per minute the resultant product being of high quality.

China and India together account  for more than 90% of the total production of the 20-100 grams of silk fabric variety in the world; China producing approximately 78% and India approximately 15% being the two major producers of silk in the world.

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Monday, 19 December 2011

Difference between Kora and Katan

This terminology is used in context of Varanasi Saris. In general, warp yarn is not degummed while weft yarn is degummed. Warp yarn is can be single or two ply. Weft yarn is twisted-two ply.

Non degummed two ply yarn is called Kora. When it is degummed, it is called Katan.

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Sunday, 11 December 2011

Kota Saris- My Thoughts

Kota sari weaving is at the crossroads. At least I think so. With my recent visit to kota sari weaving clusters in  Kota, Bundi and Baran Distt, I have come to conclusions which are very different to those I previously had. One, the battle between handloom and powerloom Kota is clearly one-sided in favour of powerloom. In clusters it is a battle between master weavers and labourers. Kota has started adopting techniques of Chanderi saris in a big way. With influence of retail chain and designers, the Kota is being experimented on different bases. With all that at background, the uniqueness of Kota sari weaving is still prevailing. With the continuous increase in the price of traditional raw material and labour, and with decreasing prevalence of saris, the road ahead for Kota weaving  is quite bumpy.

1. Handloom Vs. Powerloom

Handloom weaving in Kota Sari has shrunk itself in tiny clusters around the district. With about 2000 handlooms in the ten or so clusters around the towns, the handloom weaving is struggling to survive the onslaught of powerloom fabric being thrown in from Varanasi and from Kota itself. The difference in the price is staggering. A plain handloom sari of 5.5 meter will cost you 1200 whereas the same sari in powerloom you can get under 300 or so if you are a good bargainer.  Real zari prices will sky rocket the MRP whereas in Tested Zari they become affordable. And go to Bhairo Gali in Kota, the shops are brimming with powerloom material in tested zari at prices that will take your breath away. The only solace for Kota handloom weavers is the traditional Jamdani technique which can only be done on a handloom fabric. In fact the entire village of Kaithoon is surviving on this. However, go to markets and you get a cutwork variety of the fabric in both pallu, body and border. Number of Khats are shrinking to about 240 in powerloom whereas they are still 290-300 in the handloom fabric. Talking of Khats, I happen to see a sari in 400 khats with one of the master weaver in Kaithoon. In Kaithoon, they have stopped producing the plain poth or simple Kota material without  buti, as the workers do not get enough margins. This can directly be tracked to the powerloom version of plain poth saris.

2. Master Weavers vs. Labourers

The rift is evident. Some clusters like Kaithoon has a plethora of master weavers whereas the others such as Kotswan have all laborers. They even said that they are being exploited by the master weavers and would like to become independent. But they don't have the marketing wherewithals. The difference is also evident in their life styles. Whereas master weavers are living in plush lifestyles, the laborers are facing destitution. Even between villages the difference in the lifestyle of master weavers is stark. A master weaver in Kaithoon is much more rich than that in Ratoda. As indicated in the previous paragraph, the weavers in villages other than Kaithoon are ready to do even plain poth. 

3. Chanderi influence in Kota  

It is not clear if the motifs and techniques are originally from Kota or from Chanderi. However the difference is minimal. Using the same "Jala" technique ( In Chanderi they call it "Nakka") they are putting motifs in the pallu using "Tillis". In powerloom, they are using Jacquards and producing motifs in the cutwork technique. The motifs are so similar to Chanderi that it is difficult to guess who is copying whom. However, one difference in handloom separates Kota from Chanderi. Apart from texture, in Kota they are still using real zari. The looms are also much smaller than chanderi. 

4. Experiments on New Bases 

With the powerloom rapidly gaining ground, new bases are being experimented upon. Using Silk with Katan makes the Kota texture very soft and lightweight. Using china silk with Silk gives a medium stiffness. However they are using China x china and that gives Kota sari a very unique finish. They are also using zari to make tissue saris out of it. Use of Dyed yarns will give a very different textures to the saris. 

5. Different Areas Different Emphasis

One observation while visiting clusters I made is different clusters are specialised in different techniques. In Kaithoon, they specialise in Buti weaving using Tillis. In Kotswan they are working on plain poth using different bases. In Ratoda, they are working on Kota saris with zari checks for traditional Rajput wedding. In Mangrol, they are working on different bases.

6. Uniqueness Still Prevails

All said and done, the texture that Kota sari produces in inimitable. With options of so many bases using yarn dyed and butis with border options, they become a language in themselves. 

7. Road Ahead

Handloom in Kota is dyeing like any other handloom cluster. The progeny of the handloom weavers doesn't want to work on traditional looms. With designs being copied by everyone else, and powerloom option coming the second day with half the price, weavers are dyeing a slow death. Buti option in Jamdani technique still makes the saris unique. With GI in place, and government supporting Kota weavers, it makes the life of the weavers somewhat comforting. However this incentive is artificial and until some unique design interventions are done in Kota saris, the handloom extinction is only an arm's length away.

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