🐞 Silk Reeling and Post-Cocoon Technology

Post-cocoon technology converts biological production into market-grade silk through stifling, reeling, grading, and by-product recovery.

---

Principles of Silk Reeling

Silk reeling is the process of unwinding the continuous silk filament from cocoons. Before reeling, cocoons are stifled (killing the pupa inside) to prevent moth emergence, which would break the filament. Stifling is done by sun drying, hot-air drying, or steam treatment. The cocoons are then stored until reeling.

During reeling, cocoons are first softened by cooking (boiling or steaming) in water, which dissolves the sericin gum partially and loosens the filament ends. The operator locates the filament end by brushing the cocoon surface and draws it out. Multiple filament ends (4-8 cocoons) are combined and twisted together to form a single raw silk thread. The quality of raw silk depends on uniformity, lustre, strength, and cleanness.

Reeling Methods

The three main reeling systems used in India are as follows. Charka reeling is the simplest and most traditional method, using a hand-operated device. It produces coarse, uneven silk of lower quality and is gradually being phased out. Cottage basin reeling involves a semi-mechanized basin with hot water and a hand-operated reel. It produces better quality silk than charka but is still labour-intensive. Multiend reeling is the most advanced method, where a single operator manages multiple reeling ends simultaneously with automatic filament-end detection and joining. It produces high-quality silk meeting international standards and is used in modern reeling units.

Silk Grades

Raw silk is graded based on several parameters including denier (thickness), tenacity (breaking strength), elongation, cohesion, cleanness (absence of waste and neatness), and evenness. International silk grading standards classify silk into grades such as A, B, C, and D, with A being the highest quality. Indian silk is often graded under the Bureau of Indian Standards (BIS) system. Bivoltine silk from India is increasingly meeting international quality benchmarks, making it competitive in global markets.

By-Products of Silk Reeling

Several valuable by-products are recovered during the reeling process. Silk waste (unreelable portions) is processed into spun silk yarn for textiles. Sericin, the gum protein removed during degumming, is recovered and used in cosmetics, wound dressings, and biomedical applications due to its moisture-retaining and biocompatible properties. Silkworm pupae, rich in protein (approximately 55% crude protein) and fat, are used as animal feed, fish feed, or processed into oil for industrial applications. In northeast India and parts of southeast Asia, silkworm pupae are consumed as a traditional food source.

Non-Mulberry Silks (Vanya Silks)

India is unique in producing all four commercially known types of silk. Besides mulberry silk, three non-mulberry (vanya) silks are produced. Tasar silk is produced by Antheraea mylitta, which feeds on Terminalia and Shorea trees, mainly in Jharkhand, Chhattisgarh, and Odisha. It has a natural golden-brown colour. Eri silk (ahimsa silk) is produced by Samia cynthia ricini, feeding on castor leaves, primarily in Assam and other northeastern states. It is called ahimsa silk because the pupa is not killed during processing as the moth is allowed to emerge before silk extraction. Muga silk is the rarest and most prestigious silk, produced exclusively in Assam by Antheraea assamensis, feeding on som (Machilus bombycina) and soalu trees. It has a natural golden lustre that improves with washing and has received a Geographical Indication (GI) tag.

---

Summary Cheat Sheet

• Reeling starts with proper cocoon stifling and cooking.
• Multiend reeling gives higher consistency than charka and cottage systems.
• Silk quality is judged by denier, strength, evenness, and cleanness.
• Sericin, pupae, and silk waste are valuable post-cocoon by-products.

References

1 source • [1]

[1]

Standard post-cocoon and silk reeling references used for lesson preparation.