Raw Silk
Raw silk is the continuous protein filament reeled from the cocoon of the silkworm, most commercially Bombyx mori fed on mulberry. Each cocoon yields a single unbroken filament of fibroin held together by a gum called sericin, and several filaments are reeled together to make one thread of a stated thickness. Silk is the only natural continuous filament fibre, which is why it is smooth, strong for its weight and unmatched in lustre and drape. It goes into woven dress and furnishing fabric, scarves and ties, knitwear, sewing thread and embroidery, surgical suture, and technical applications where a strong biocompatible protein filament is wanted. Wild or non mulberry silks, tussah, eri and muga, are reeled or spun separately and trade on their own terms.
Listed raw silk markets
Each line is a grade at a delivery point. Open one for its full specification and terms.
Grades
Raw silk is contracted on the reeled size in denier and the classification that measures how evenly that size is held along the thread, together with cleanliness, neatness, cohesion and tenacity.
Fibre identity and species
4 grades
| Grade | Definition |
|---|---|
| Silkworm species and feedDeclared | Bombyx mori reeled on mulberry, or the non mulberry silks, tussah from Antheraea, eri from Samia and muga from Antheraea assamensis. They are separate fibres with separate properties and are never sold interchangeably. |
| Reeling methodDeclared | Hand reeled, cottage basin, multi-end reeled or automatic reeled. The reeling route is the strongest predictor of evenness and it is named on the contract. |
| Product formDeclared | Raw reeled silk in skeins, doubled or thrown yarn, dupion, silk waste, noil or spun silk. Each is a different trade. |
| Degumming stateDeclared | Raw silk still carrying its sericin, partially degummed, or fully degummed. The gum is roughly a fifth of the raw weight and the weight basis has to say which state applies. |
Fineness and dimensional measurement
10 grades
| Grade | Definition |
|---|---|
| Size, nominal denierDenier | The linear density the thread was reeled to, measured as mass per standard length on a wrap reel. It is the primary description of a raw silk lot. |
| Size deviationDenier | The variation of the actual size around the nominal, measured under ISO 15625 across many skeins. It is the core evenness measurement in the classification. |
| Maximum deviationDenier | The single largest departure from the nominal size found in the lot. |
| Evenness variationPercentage, against the reference photographs | Visual evenness assessed on a seriplane board against the standard panels, reported as major and minor faults. |
| CleannessPoints, against the standard panels | Large visible defects on the seriplane board: slugs, loops, waste and split ends. |
| NeatnessPercentage, against the standard panels | Fine surface irregularity and small nibs assessed on the seriplane board. |
| TenacityGrams force per denier, minimum | Tensile strength of the reeled thread. |
| Elongation at breakPercentage | Determined under ISO 5079 on the conditioned thread. |
| CohesionNumber of strokes | How well the constituent filaments hold together under rubbing, which decides whether the thread survives weaving without extra throwing. |
| Winding testBreaks per stated length | Breaks recorded during rewinding, the practical test of whether a lot will run in a mill. |
Commercial grade classification
9 grades
| Grade | Definition |
|---|---|
| 6AClassification grade | The highest classification. Reserved for automatic reeled silk holding the tightest size deviation with near flawless evenness, cleanness and neatness. |
| 5AClassification grade | Very high evenness and cleanness, standard for fine woven and knitted apparel. |
| 4AClassification grade | High grade reeled silk for general apparel weaving. |
| 3AClassification grade | Good commercial grade with a wider size deviation. |
| 2AClassification grade | Commercial grade, with visible evenness and cleanness faults permitted. |
| AClassification grade | The base classification grade. |
| B and belowClassification grade | Off grade silk for furnishing, blending and lower specification uses. |
| Ungraded and cottage reeledClassification grade | Hand and cottage basin reeled silk offered outside the classification, contracted on sample and on the measured size alone. |
| Non mulberry silksNamed on the contract | Tussah, eri and muga, classified on their own conventions and never offered under a mulberry grade letter. |
Physical and mechanical measurement
5 grades
| Grade | Definition |
|---|---|
| Moisture regainPercentage, at the standard atmosphere | Measured at the conditioning house under ISO 139. Silk is bought at a contractual regain and the conditioned weight is the invoiced weight. |
| Sericin contentPercentage by mass | The gum fraction. It sets the loss on degumming and therefore the true fibroin weight being bought. |
| ColourAgainst the reference sample | Natural white, cream or yellow according to the worm race and feed, or the natural golden and honey shades of the non mulberry silks. |
| Skein and hank formDeclared, with the skein weight and the book weight | How the lot is put up, which decides how it feeds a winding frame. |
| Foreign matterDeclared, zero tolerance where specified | Any non silk material in the skein. |
Delivery, packing and certification
10 grades
| Grade | Definition |
|---|---|
| Baling and packingDeclared, with the bale weight and the pack material | Pressed bales, hydraulic bales, hanks or bundles, with the wrapping named. Synthetic wrap is excluded where contamination is a contract term. |
| Marking and lot identityDeclared | Bale marks, lot number and the test certificate number, tied to the sample retained by both parties. |
| Test certificateCertificate, with the issuing house | An independent test house certificate is the contract document in this trade and the lot is settled against it. |
| Sampling methodDeclared | Core sampling, grab sampling or full lot testing, with the number of bales sampled written into the contract. |
| Fumigation and phytosanitary treatmentDeclared, with the certificate | Named where the destination requires it for a plant or animal origin fibre. |
| CertificationCertificate, with the scheme and the certificate number | Organic, Responsible Wool, Responsible Alpaca, Responsible Mohair, Fairtrade or a private buyer standard, named on the contract when it is contracted. |
| Clip or crop yearDeclared | The shearing season or the harvest year, recorded with the lot. |
| Conditioning house certificateCertificate, with the issuing house | The conditioned weight and the classification certificate are the contract documents in the silk trade and the lot settles against them. |
| Reeling seasonDeclared | The rearing crop the cocoons came from, recorded with the lot. |
| Bale and book packingDeclared, with the bale weight | Skeins tied into books, books pressed into bales, wrapped and marked. |
Grades outside this list trade on request. Send us the contract specification you work to and we will price against it.
Locations
| Country | Region | We trade it as |
|---|---|---|
| China | Guangxi, Sichuan, Zhejiang, Jiangsu, Yunnan and Chongqing | Origin and destination |
| India | Karnataka, Andhra Pradesh, Tamil Nadu, West Bengal, Assam and Jammu and Kashmir | Origin and destination |
| Uzbekistan | Fergana, Bukhara, Samarkand and Andijan | Origin and destination |
| Brazil | Parana and Sao Paulo | Origin and destination |
| Vietnam | Lam Dong and the Central Highlands | Origin and destination |
| Thailand | the Northeast, Isan | Origin and destination |
| Iran | Gilan and Mazandaran | Origin and destination |
| North Korea | the western provinces | Origin and destination |
| Turkey | Bursa and the Marmara region | Origin and destination |
| Japan | Gunma, Fukushima and Nagano | Origin and destination |
| Madagascar | the central highlands, wild silk | Origin and destination |
| Cambodia | Takeo and Kampong Cham | Origin and destination |
| Italy | Como, Biella and Prato, weaving and printing | Destination |
| France | Lyon and Auvergne-Rhone-Alpes | Destination |
| Romania | Bucharest and Prahova | Destination |
| Germany | Baden-Wurttemberg and North Rhine-Westphalia | Destination |
| United Kingdom | England, Macclesfield and the accessories trade | Destination |
| Spain | Catalonia and Valencia | Destination |
| Switzerland | Zurich and Basel | Destination |
| United States | New York, North Carolina and California | Destination |
| South Korea | Gyeonggi and Daegu | Destination |
| Hong Kong | trading, finance and quality control | Destination |
| Bangladesh | Rajshahi and Dhaka | Destination |
| Pakistan | Punjab and Karachi | Destination |
| Indonesia | South Sulawesi and Java | Destination |
| Malaysia | Selangor and Penang | Destination |
| United Arab Emirates | Dubai, re-export and retail | Destination |
| Saudi Arabia | Riyadh and Jeddah | Destination |
| Morocco | Casablanca and Fez | Destination |
| Egypt | Cairo and Alexandria | Destination |
| Portugal | Porto and Covilha | Destination |
| Poland | Lodz and Mazovia | Destination |
Origins and destinations outside this list trade on request. We are not limited to the locations shown here.
Timing
Harvest is when the cocoon crop is reared and reeled at origin. Arrival is when a shipment from that origin typically lands in a consuming market. The gap between them is reeling, conditioning, classification and the voyage.
HarvestArrival
| Origin | J | F | M | A | M | J | J | A | S | O | N | D | Window |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| China | Harvest | Harvest | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Arrival | Arrival | Harvest May to Oct, arrival Jul to DecMultiple rearing crops from late spring through autumn in the subtropical south, fewer and later in the Yangtze provinces. Reeling and conditioning follow each crop, so offering is close to continuous from mid year. | ||||
| India | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest Jan to Dec, arrival Jan to DecKarnataka and Tamil Nadu rear multivoltine crops year round, so Indian raw silk supply is continuous. The Assam muga and eri crops run on their own narrower windows. |
| Uzbekistan | Harvest | Harvest | Arrival | Arrival | Arrival | Harvest May to Jun, arrival Jul to SepA single spring rearing crop timed to the mulberry leaf, reeled through the summer. | |||||||
| Brazil | Harvest and arrival | Harvest and arrival | Harvest and arrival | Arrival | Arrival | Harvest | Harvest | Harvest and arrival | Harvest Oct to Mar, arrival Dec to MayRearing across the warm months in Parana, reeled and conditioned for export from the end of the year. | ||||
| Vietnam | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest Jan to Dec, arrival Jan to DecContinuous rearing in the Central Highlands, with the crop thinning in the coolest months. |
| Thailand | Arrival | Harvest | Harvest | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Harvest and arrival | Arrival | Harvest May to Nov, arrival Jul to JanRearing through the warm and wet season, with hand reeled and cottage lines dominating. |
Windows outside this pattern trade on request, including carry, forward positions and stock already sitting in a destination warehouse.
Customs, packing and contract terms
Indicative terms for raw silk. Tariff classification is the importer’s responsibility and limits change, so confirm both against the destination customs authority and the current regulation before you fix a contract.
- HS heading5002.00 Raw silk, not thrown
5001.00 Silkworm cocoons suitable for reeling - PackingCompressed bales. Jute and sisal at 180 kg to 250 kg, animal fibre at 100 kg to 300 kg pressed under hessian or polypropylene wrap, silk in cartons. Bale identification must carry the lot and the test certificate number.
- Container loading20ft: 10 t to 18 t depending on bale density. Wool, cashmere and other animal fibres are volume limited well before weight.
- Contract and arbitrationIWTO Blue Book terms with IWTO core test certificates and arbitration under IWTO rules for wool and fine animal hair. Plant fibres on the contract of the origin trade association or on CIF terms with arbitration at the named seat.
- Destination limitsPhytosanitary certification for plant fibres under Regulation 2016/2031 and veterinary health certification for animal fibre under Regulation 2016/429 and Regulation 142/2011. EU REACH restrictions on residual dyes, biocides and azo colourants. CITES prohibits trade in shahtoosh and controls vicuna.
Common questions
What grades of raw silk does SIP Global trade?
We quote 38 published grades of raw silk, including Silkworm species and feed - Declared, Reeling method - Declared, Product form - Declared, Degumming state - Declared, Size, nominal denier - Denier and Size deviation - Denier. Every grade is tied to a delivery point and a settlement route. Grades outside the published list are priced on request.
How is raw silk graded?
Raw silk is contracted on the reeled size in denier and the classification that measures how evenly that size is held along the thread, together with cleanliness, neatness, cohesion and tenacity. Grading runs on 5 systems: Fibre identity and species, Fineness and dimensional measurement, Commercial grade classification, Physical and mechanical measurement and Delivery, packing and certification.
Where does SIP Global trade raw silk?
We trade raw silk in China, India, Uzbekistan, Brazil, Vietnam, Thailand, Iran and North Korea and 24 further markets. Origins and destinations outside this list trade on request. We are not limited to the locations shown.
When is raw silk harvested and when does it arrive?
Typical windows are China: harvest may to oct, arrival jul to dec; India: harvest jan to dec, arrival jan to dec; Uzbekistan: harvest may to jun, arrival jul to sep; Brazil: harvest oct to mar, arrival dec to may; Vietnam: harvest jan to dec, arrival jan to dec. Harvest is when the lot is taken at origin, arrival is when a shipment from that origin lands in a consuming market. Windows outside this pattern, including carry, trade on request.
What is the HS code for raw silk?
Raw silk is normally classified under HS 5002.00 (raw silk, not thrown) and HS 5001.00 (silkworm cocoons suitable for reeling). The heading follows the form the goods are in at the border, and national tariffs extend it beyond six digits, so confirm the full line with the destination customs authority before you fix a contract.
How do I get a price for raw silk?
Send the grade, the origin and the delivery window to the SIP Global desk. That is enough for a trader to come back with a level and a settlement route. 1 listed raw silk market is published on this page, each with its full specification and terms. We take both sides, physical and financial, prompt to long dated.
Standards and data sources
The grading language on this sheet follows published standards. Trade volumes and tariff lines are public record. Verify anything here against the source.
- ISOInternational Organization for Standardization
- IPPCInternational Plant Protection Convention phytosanitary measures
- UN ComtradeOfficial international trade statistics by HS code
- ITC Trade MapBilateral trade flows and tariff data
- FAOSTATFAO production and trade series for agricultural commodities
Price this with our desk
Grade, origin and window if you have them. If what you are carrying does not fit the sheet above, describe it in your own words and a trader will take it from there.