Cork
Cork is the outer bark of the cork oak, Quercus suber, stripped from the living tree by hand and regrown by the tree over a cycle of roughly nine years. It is a closed cell material, made of millions of gas filled cells with waxy walls, which is why it is light, compressible, elastic, impermeable to liquid, slow to burn and a poor conductor of heat and sound. The first strip from a young tree is coarse and irregular and is used for granulate and insulation; later strips from a mature tree are even and are the material from which natural wine stoppers are punched. The traded forms are raw planks straight from the tree, boiled and flattened planks, punched natural stoppers, technical and agglomerated stoppers, granulate of graded particle size, and sheet, roll and block used in flooring, insulation, gaskets, expansion joints and sports goods. Buyers are stopper manufacturers, flooring and insulation makers, gasket and seal producers, and the wine and spirits industry that stands behind the stopper trade.
Listed cork markets
Each line is a grade at a delivery point. Open one for its full specification and terms.
Grades
Cork is bought on the type of strip, on thickness and on the visual quality of the plank, because those decide whether a plank can be punched for stoppers or only ground for granulate. Every parameter names how it is measured. The taint compounds that can transfer to wine are tested by defined analytical methods rather than by smell alone, and the test basis is written into the contract.
Species, form and identification
7 grades
| Grade | Definition |
|---|---|
| SpeciesQuercus suber, confirmed by the plantation record and by bark structure | Cork of commerce comes from the cork oak. Bark from other oaks is not cork and is not traded as such. |
| Strip typeDeclared, as virgin cork, second cork, or reproduction cork | Virgin cork is the first strip from a young tree, hard and irregular. Second cork is the next strip, still irregular. Reproduction cork is every later strip and is the only material from which natural stoppers can be punched. |
| Strip cycle positionDeclared as the number of years since the previous strip | The regrowth period governs thickness. A plank taken early is thin and a plank taken late is thick and coarse, so the interval is recorded rather than assumed. |
| FormDeclared, as raw plank, boiled plank, punched stopper, technical stopper, agglomerated product, granulate, sheet, roll, or block | Each form carries its own specification and its own testing regime. |
| Boiling and stabilisationDeclared, as the boiling schedule applied and the stabilisation period after it | Planks are boiled in clean water to flatten them, clean them and expand the cells, then rested before punching. The schedule and the rest period are part of the description. |
| Agglomerate binderDeclared where the product is agglomerated, naming the binder and the density target | Polyurethane and other binder systems behave differently in a bottle and in a floor, so the binder is named rather than left to the product name. |
| Surface treatmentDeclared, as untreated, washed, surface treated, or coated | Stoppers receive a surface treatment that governs insertion and extraction force, and the treatment is specified because it changes the behaviour of the closure. |
Grading and appearance
8 grades
| Grade | Definition |
|---|---|
| Visual classAssessed by counting and measuring the pores on the two faces of the plank or the body of the stopper | The primary quality ladder in cork. Porosity is judged by pore number, pore size and their distribution across the surface, against the class definitions written into the contract. |
| Porosity coefficientMeasured as the percentage of the surface area occupied by pores, by image analysis of a prepared face | A measured value rather than a visual impression, used where the parties want the class to be reproducible. |
| Defect assessmentMeasured on each defect type as its dimension and position on the piece | Green cork, insect galleries, woody inclusions, cracks, nail marks, ant damage and yellow stain are each recorded by size and location, since a defect at the sealing surface matters and the same defect in the body may not. |
| Belly and back conditionInspected on both faces of the plank | The belly is the inner face against the tree and the back is the outer weathered face. Both are inspected because the punchable band lies between them. |
| Colour and uniformityAssessed visually under daylight against a retained sample | Recorded against a retained reference rather than a colour name, since cork darkens with boiling and with age. |
| Granulate particle sizeDetermined by sieving through stated apertures and reporting the mass retained on each | Granulate is contracted on a sieve distribution in millimetres, not on a trade name such as fine or coarse. |
| Granulate densityDetermined as bulk density on a measured volume of the sieved fraction | Governs how the granulate performs in an agglomerated product and is measured on the delivered fraction. |
| Stopper dimensional classMeasured on diameter and length of the individual stopper | Sorted by measured dimension with the tolerance stated, since the closure has to match the bottle neck it is going into. |
Dimensions and measurement
6 grades
| Grade | Definition |
|---|---|
| Plank thicknessMeasured with a calliper at defined points across the plank | Recorded in millimetres. Thickness decides whether the plank can be punched for a stopper of a given length and is the single most important dimension in the raw trade. |
| Plank areaMeasured as length by width on the plank | Recorded with the pieces of small area separated out, since small planks yield fewer stoppers per unit mass. |
| Stopper diameterMeasured with a calliper or by automatic gauging on each piece | Recorded in millimetres with the tolerance stated, at a defined temperature and humidity, because cork dimensions move with moisture. |
| Stopper lengthMeasured with a calliper or by automatic gauging on each piece | Recorded in millimetres with the tolerance stated. |
| Sheet and roll dimensionsMeasured on thickness, width and length | Recorded with the thickness tolerance and the flatness requirement stated separately. |
| Quantity basisDeclared, as weight for planks and granulate, and piece count for stoppers | Stated explicitly, with the moisture condition named where the material is sold by weight. |
Physical and moisture condition
9 grades
| Grade | Definition |
|---|---|
| Moisture contentDetermined by oven drying to constant mass, on a representative sample | Reported as a percentage of the dry mass. Cork is contracted within a moisture band, because dry cork is brittle and wet cork will mould. |
| Apparent densityDetermined as mass divided by measured volume of the piece | Reported for stoppers and for agglomerated product, since density governs compression and recovery. |
| Compression and recoveryTested by the standard method named in the contract, on a stated number of pieces | The closure has to compress into a neck and recover against it. Both the compression force and the recovered diameter after a stated interval are measured. |
| Extraction forceTested on bottled samples by the standard method named in the contract | Measured in newtons after a stated period in the bottle, since the closure must be removable as well as sealing. |
| Capillarity and sealingTested by the liquid tightness method named in the contract | Bottled samples are held under stated conditions and inspected for leakage and for liquid rise in the closure. |
| Releasable TCADetermined by the standard maceration and gas chromatography method named in the contract | 2,4,6 trichloroanisole is the compound responsible for cork taint. It is measured analytically on a representative sample and reported against a contractual limit. |
| Peroxide residueDetermined by the standard method where the material has been washed with a peroxide system | Residual oxidant is measured, since it can carry through to the bottled product. |
| Dust contentDetermined by sieving or by air separation on a weighed sample of stoppers | Reported as mass per piece or as a percentage, because dust carried into the bottle is a defect. |
| Microbiological conditionDetermined by the plate count method named in the contract | Mould and yeast counts on finished closures, tested against a stated limit. |
Legality, certification and phytosanitary status
8 grades
| Grade | Definition |
|---|---|
| Harvest legalityDocumented against the property record and the stripping authorisation for the cork oak stand | Cork oak stands are protected in the principal producing countries and stripping is regulated as to interval and to method. |
| Stripping interval complianceDocumented as the year of the previous strip on the stand | The minimum regrowth interval is set by law in the producing countries, and the harvest record evidences it. |
| Deforestation regulation statusAssessed against the destination requirements applying to the product | Where the destination requires a due diligence statement or geolocation of the harvest area, that evidence is assembled before shipment. |
| CertificationDeclared, as the forest management or chain of custody scheme, the certificate number and the claim made | Certified cork is widely traded and the certificate scope is checked against the actual stand and the actual product. |
| Food contact complianceDocumented against the food contact requirements of the destination | Closures are a food contact material. The declaration of compliance and the supporting migration evidence travel with the shipment. |
| Phytosanitary certificateIssued by the national plant protection organisation of the exporting country where required | Raw and boiled plank generally require certification. Finished closures usually do not, and the position is confirmed for the destination before shipment. |
| Wood packagingISPM 15 treatment of any wood packaging material used | Applies to the crates and pallets independently of the cargo. |
| Tariff classificationHarmonized System classification agreed before shipment | Natural cork, agglomerated cork and finished articles classify separately, and the classification is agreed in advance. |
Inspection, documentation and settlement
9 grades
| Grade | Definition |
|---|---|
| InspectionBy an independent inspection company, or by a buyer appointed grader, named in the contract | Grading, tally, measurement and condition checked at loading or at discharge as agreed, with a report and photographs issued to both parties. |
| TallyPiece by piece or by parcel, as the contract states | The count and measurement record that the invoice is built from, signed by both parties or by the appointed inspector. |
| Measurement basisDeclared, as the standard and the moisture condition the volume is calculated at | Named explicitly, because volume in this trade depends on the rule applied and on whether the material is green or dried. |
| Grading disputeResolved by a reinspection under the named rule, by an agreed independent grader | The reinspection procedure, the time limit for claiming and who bears the cost are all written in. |
| Phytosanitary certificationIssued by the plant protection organisation of the exporting country | Names the treatment applied and travels with the cargo. Required by most destinations for wood and wood products. |
| Legality documentationHarvest permit chain, transport permits, export permit and the due diligence statement where required | The document set that proves lawful origin, assembled before shipment because it cannot be reconstructed afterwards. |
| Certification and chain of custodyDeclared, as the scheme, the certificate number and the claim made | Where the material is sold as certified, the certificate scope must cover the actual species and the actual harvest area. |
| Payment termsDocumentary credit, cash against documents or open account, as agreed | Stated with the provisional and final invoice mechanism where the settlement depends on a tally or a grading at discharge. |
| Insurance and carriageDeclared, with the Incoterm and the insured value | The Incoterms rule named with the version year, and the party carrying the risk over each leg. |
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 |
|---|---|---|
| Portugal | Europe | Origin and destination |
| Spain | Europe | Origin and destination |
| Morocco | Africa | Origin and destination |
| Algeria | Africa | Origin and destination |
| Tunisia | Africa | Origin and destination |
| Italy | Europe | Origin and destination |
| France | Europe | Origin and destination |
| Greece | Europe | Origin and destination |
| Turkey | Europe and Middle East | Origin and destination |
| Croatia | Europe | Origin and destination |
| United States | North America | Origin and destination |
| Canada | North America | Origin and destination |
| Chile | South America | Origin and destination |
| Argentina | South America | Origin and destination |
| Australia | Oceania | Origin and destination |
| New Zealand | Oceania | Origin and destination |
| South Africa | Africa | Origin and destination |
| United Kingdom | Europe | Origin and destination |
| Germany | Europe | Origin and destination |
| Netherlands | Europe | Origin, destination and trading hub |
| Belgium | Europe | Origin, destination and trading hub |
| Switzerland | Europe | Origin and destination |
| Austria | Europe | Origin and destination |
| Poland | Europe | Origin and destination |
| China | Asia | Origin and destination |
| Japan | Asia | Origin and destination |
| South Korea | Asia | Origin and destination |
| India | Asia | Origin and destination |
| United Arab Emirates | Middle East | Origin, destination and trading hub |
| Brazil | South America | Origin and destination |
| Mexico | North America | Origin and destination |
Origins and destinations outside this list trade on request. We are not limited to the locations shown here.
Timing
Harvest is when the material is cut or stripped at origin, which follows the dry season, the growth cycle or the felling licence period in that country. Arrival is when a shipment from that origin typically lands in a consuming market. The gap between them is seasoning, sawing or processing, the permit and phytosanitary procedure and the voyage.
HarvestArrival
| Origin | J | F | M | A | M | J | J | A | S | O | N | D | Window |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Portugal | Harvest | Harvest | Harvest and arrival | Harvest and arrival | Arrival | Arrival | Arrival | Harvest May to Aug, arrival Jul to NovThe largest producer. Stripping runs through the summer while the bark separates cleanly from the tree, followed by a rest period before boiling. | |||||
| Spain | Harvest | Harvest | Harvest and arrival | Arrival | Arrival | Arrival | Harvest Jun to Aug, arrival Aug to NovStripped through the summer in Extremadura, Andalusia and Catalonia, with Catalonia the traditional stopper manufacturing centre. | ||||||
| Morocco | Harvest | Harvest | Harvest and arrival | Arrival | Arrival | Arrival | Harvest Jun to Aug, arrival Aug to NovSummer stripping in the Atlantic forests, with much of the plank moving to Iberian processors. | ||||||
| Algeria | Harvest | Harvest | Harvest and arrival | Arrival | Arrival | Arrival | Harvest Jun to Aug, arrival Aug to NovSummer stripping, shipping plank and granulate into the Mediterranean processing trade. | ||||||
| Tunisia | Harvest | Harvest | Harvest and arrival | Arrival | Arrival | Arrival | Harvest Jun to Aug, arrival Aug to NovSummer stripping in the northern forests, supplying plank and granulate. | ||||||
| Italy | Harvest | Harvest | Harvest and arrival | Arrival | Arrival | Arrival | Harvest Jun to Aug, arrival Aug to NovSardinian stripping through the summer, with regional stopper manufacture. | ||||||
| France | Harvest | Harvest | Harvest and arrival | Arrival | Arrival | Arrival | Harvest Jun to Aug, arrival Aug to NovCorsican and southern mainland stands, stripped in summer, with volume small relative to Iberia. | ||||||
| Greece | Harvest | Harvest | Harvest and arrival | Arrival | Arrival | Arrival | Harvest Jun to Aug, arrival Aug to NovSmall production stripped in summer and processed regionally. | ||||||
| Turkey | Harvest | Harvest | Harvest and arrival | Arrival | Arrival | Arrival | Harvest Jun to Aug, arrival Aug to NovAegean and Mediterranean stands stripped in summer, largely processed domestically. | ||||||
| Croatia | Harvest | Harvest | Harvest and arrival | Arrival | Arrival | Arrival | Harvest Jun to Aug, arrival Aug to NovSmall Adriatic production, stripped in summer. |
Windows outside this pattern trade on request, including term supply, forward positions and stock already seasoned and sitting in a destination warehouse.
Customs, packing and contract terms
Indicative terms for cork. 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 heading4501.10 Natural cork, raw or simply prepared
4501.90 Waste cork, crushed, granulated or ground - PackingRaw planks in stacked bales strapped on pallets, granulate in big bags, discs and stoppers in cartons. Post boiling moisture and TCA screening result stated at load.
- Container loading20ft: 8 t to 12 t of planks, volume limited. Granulate at 14 t to 18 t.
- Contract and arbitrationATIBT contracts for tropical hardwood or the terms of the origin association, with arbitration under ATIBT rules or at the contract seat. NHLA grading rules where the destination is North America.
- Destination limitsEUDR (Regulation 2023/1115) due diligence with plot geolocation and legality evidence, US Lacey Act declaration, CITES listing for agarwood, ramin and several rosewoods, and ISPM 15 treatment marking on all wood packaging material.
Common questions
What grades of cork does SIP Global trade?
We quote 47 published grades of cork, including Species - Quercus suber, confirmed by the plantation record and by bark structure, Strip type - Declared, as virgin cork, second cork, or reproduction cork, Strip cycle position - Declared as the number of years since the previous strip, Form - Declared, as raw plank, boiled plank, punched stopper, technical stopper, agglomerated product, granulate, sheet, roll, or block, Boiling and stabilisation - Declared, as the boiling schedule applied and the stabilisation period after it and Agglomerate binder - Declared where the product is agglomerated, naming the binder and the density target. Every grade is tied to a delivery point and a settlement route. Grades outside the published list are priced on request.
How is cork graded?
Cork is bought on the type of strip, on thickness and on the visual quality of the plank, because those decide whether a plank can be punched for stoppers or only ground for granulate. Every parameter names how it is measured. The taint compounds that can transfer to wine are tested by defined analytical methods rather than by smell alone, and the test basis is written into the contract. Grading runs on 6 systems: Species, form and identification, Grading and appearance, Dimensions and measurement, Physical and moisture condition, Legality, certification and phytosanitary status and Inspection, documentation and settlement.
Where does SIP Global trade cork?
We trade cork in Portugal, Spain, Morocco, Algeria, Tunisia, Italy, France and Greece and 23 further markets. Origins and destinations outside this list trade on request. We are not limited to the locations shown.
When is cork harvested and when does it arrive?
Typical windows are Portugal: harvest may to aug, arrival jul to nov; Spain: harvest jun to aug, arrival aug to nov; Morocco: harvest jun to aug, arrival aug to nov; Algeria: harvest jun to aug, arrival aug to nov; Tunisia: harvest jun to aug, arrival aug to nov. 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 cork?
Cork is normally classified under HS 4501.10 (natural cork, raw or simply prepared) and HS 4501.90 (waste cork, crushed, granulated or ground). 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 cork?
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 cork 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.
- 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.