Processing of Tasar Cocoons

1. Tasar Cocoon Sorting

Salient features of technology:

• User friendly, easy to operate and occupies less space.
• Traditionally, the cocoons are separated manually without the use of any equipment.
• This invention shall help to separate the cocoons in a systematic manner, into A, B and C grade cocoons, with capacity to separate 40000 to 50000 numbers of Tasar cocoons in one hour time with 99 % accuracy.
• The design and development of this machine is aimed at to overcome the drawbacks faced in the manual separation of the cocoons being practiced in the field.

2. Tasar Cocoon Cooking

2.1. Wet Reeling:

Tasar cocoons cannot be cooked with plain water like Mulberry cocoons, the process of cooking / softening of tasar cocoons is entirely different which allows the cocoons to boil with chemicals and to facilitate for easy unwinding of filaments.

2.1.1 Open pan cooking technique

Cooking of tasar cocoons by using Hydrogen peroxide and soda ash method has been popularized by CSTRI specially for wet reeling. Central Silk Technological Research Institute has standardized this method of cooking, which gives better tenacity as well as elongation compared to traditional cooking. This cooking is particularly suitable for wet reeling.

Cooking process developed by CSTRI has two stages as explained below.

First stage:

The tasar cocoons are taken in a metal cage, immersed in plain water and boiled for about 40 minutes. Care must be taken to ensure that the cocoons are not floating in the bath during entire process of cooking. Cocoons in the bath are allowed to cool for 30 minutes.

Second Stage:

Cocoons are then transferred to the next vessel containing the chemicals dissolved in warm water (45ºC – 60ºC) for 20 minutes, depending upon shell weight with the following recipe:

Soda                                        8 gm/litre   

Hydrogen peroxide                 10 ml/ltr

Sodium Silicate                       8 gm/litre

Cocoons are then deflossed and taken for wet reeling.

3. CSTRI Two in one Reeling cum Twisting Machine

Salient features of technology:

• HDPE Reels have been provided to reel the Tasar and Muga cocoons without imparting twist to the reeled yarn. Reeling is done on front side of the machine.
• On the rear end of machine, twisting of reeled silk can be done, which can also be operated simultaneously.
• The production of the reeling machine is about 350 gms/8 hours.
• TPI of 7 to 12 turns per inch can be imparted on the machine as compared to the 5 to 9 in the earlier version.
• Suitable for both Dry & Wet Reeling to produce very fine denier yarn
• Machine designed ergonomically
• Reduces fatigue
• All machine controls easily reachable from the sitting position
• Energy optimization
• Suitable to twist single & 2ply yarn
• Suitable to produce both Warp & Weft Yarn
• Optimized to retain better Tensile and Cohesion properties

4. CSTRI motorized reeling cum twisting machine

Salient features of technology:

• Most popular and versatile reeling machine widely used in muga and tasar silk reeling.
• Reeling and twisting of reeled silk done simultaneously.
• The production of the reeling machine is about 250 gms/8 hours.
• TPI of 5 to 9 turns per inch can be imparted on the machine.
• Suitable for both Dry & Wet Reeling of Tasar yarn
• Suitable to twist 2ply yarn
• Suitable to produce Warp Yarn
• Ensures better earning potential to the Reeler in comparison with the traditional reeling methodologies.

5. CSTRI solar operated spinning machine

Salient features of technology:

• It is more environmental friendly, economically beneficial and easily accessible.
• For easy spinning the flyer is mounted on ball bearing.
• The said machine is suitable for aged and handicapped persons and is also a low cost spinning machine.
• The bobbin provided in the machine is easily removable and the hand spun yarn produced can be wound on re-reeling machine for making standard skein.
• The machine is provided with variable speed flyer and it is easy to operate.

6. Weaving preparatory

7. CSTRI permeation chamber for silk sizing

Salient features of technology:

• Reel Permeation Chamber developed by CSTRI to size reeled silk yarn particularly suitable to size warp yarns of Tasar and Muga silk.
• Sizing: An intermediate process between Reeling and Re-reeling for enhancement of reeled yarn cohesion.
• Improves physical properties like tenacity, elongation and cohesion.
• The sized yarn can directly be used as warp as substitute to Korean / Chinese tasar silk, on Handlooms, Power looms and Shuttle less looms without imparting any twist.
• This ultimately increases the on loom weaving efficiency due to improved quality of the sized warp. 

Using the above CSTRI tasar reeling technology, warp quality Tasar silk can be produced form the available Indian tasar cocoons.

Source:

Vanya Silk Reeling Division, Central Silk Technological Research Institute, Bangalore