Natural Rubber SIR20 Specification and Container Capacity Indonesia
Complete SIR20 Technical Specification: The Full TSNR Parameter Framework
Natural Rubber SIR20 from Indonesia is graded and traded under the Technically Specified Natural Rubber (TSNR) system — a quality framework based entirely on measurable laboratory parameters rather than visual assessment. Every parameter in the SIR20 specification has a defined test method, a specified acceptance limit, and a mandatory reporting requirement in the Certificate of Analysis (CoA) that accompanies each export shipment.
For industrial buyers — tire manufacturers, rubber compounders, industrial goods producers — the TSNR specification framework provides the objective quality assurance basis that allows SIR20 from Indonesian exporters to be integrated into established compound formulations with confidence. A CoA that confirms compliance with all six SIR20 parameters from an accredited testing laboratory is the primary quality documentation that purchasing and quality assurance teams rely on to verify that received product meets specification before it enters the production process.
This guide covers every technical parameter in the SIR20 specification, its test method, its commercial significance, the full container capacity reference for 20ft and 40ft configurations, and the complete packaging and loading framework for SIR20 export from Indonesia.
Parameter 1: Dirt Content — Max 0.20%
Dirt content is the defining parameter of the SIR grade system — the "20" in SIR20 directly refers to the maximum allowable dirt content of 0.20% by weight. Dirt in natural rubber consists of particulate matter that remains insoluble after the rubber is dissolved in a suitable solvent — primarily bark fragments, soil particles, sand, and other field or processing contaminants that were incorporated into the raw material during tapping, collection, or initial processing.
Test Method
Dirt content is measured by the standard TSNR dirt test: a precisely weighed sample of approximately 10 grams of rubber is dissolved in a suitable hydrocarbon solvent (typically toluene or xylene at elevated temperature), and the solution is filtered through a 45-micron stainless steel wire mesh. The retained particulate matter is dried and weighed, and dirt content is expressed as a percentage of the original sample weight. The test is specified in ISO 249 and in the Indonesian National Standard SNI 06-1903-2000.
Commercial Significance
Dirt particles in natural rubber compound formulations act as stress concentration points — sites where microcracks initiate under dynamic loading. In tire applications where fatigue life under repeated flexing is a critical performance parameter, high dirt content in the rubber compound can reduce tire life and increase the risk of compound failure. The 0.20% maximum in SIR20 represents the upper limit that tire and industrial rubber manufacturers have established as acceptable for their standard formulations. Buyers who process rubber into demanding fatigue-critical applications may specify SIR10 (max 0.10% dirt) or SIR5 (max 0.05% dirt) to achieve additional performance safety margin.
Parameter 2: Ash Content — Max 1.00%
Ash content measures the inorganic mineral residue remaining after complete incineration of the rubber sample. Ash primarily reflects mineral contamination — soil, sand, and inorganic processing chemical residues — that was incorporated into the rubber during raw material handling or coagulation. Test method: a weighed rubber sample is incinerated at 550 degrees Celsius in a muffle furnace until constant weight, and the residue is expressed as a percentage of the original sample weight (ISO 247).
The SIR20 maximum of 1.00% ash reflects the level achievable with standard processing of cup lump raw material from well-managed Indonesian rubber plantations. High ash content can affect the physical properties of vulcanized rubber compounds — particularly tensile strength and elongation — by increasing the proportion of inorganic filler at the expense of rubber polymer content. The ash limit also serves as a control against adulteration of rubber with cheap mineral fillers, which has historically been a quality issue in some raw material sources.
Parameter 3: Nitrogen Content — Max 0.60%
Nitrogen content reflects the protein content of the natural rubber — Hevea brasiliensis latex contains naturally occurring proteins that remain in the dry rubber after processing. Nitrogen is measured by the Kjeldahl method or by combustion analysis (ISO 1656), with results expressed as weight percentage of nitrogen in the dried rubber sample.
Nitrogen content has several commercial implications. High protein (nitrogen) content affects the processing behavior of natural rubber in compound mixing — high-protein rubber tends to have higher Mooney viscosity and requires more mixing energy to achieve good dispersion of compounding ingredients. In medical device applications — gloves, catheters, and other latex products that contact skin or mucous membranes — protein content is critically important because natural rubber latex proteins are the primary cause of Type I latex allergies in sensitized individuals. The SIR20 maximum of 0.60% nitrogen is appropriate for standard industrial and tire applications; medical device applications that require minimum protein content should specify deproteinized grades with significantly lower nitrogen content.
Parameter 4: Volatile Matter — Max 1.00%
Volatile matter content measures the total weight loss from a rubber sample when heated at 100 degrees Celsius for defined periods, expressed as a percentage of the original sample weight (ISO 248). Volatile matter primarily represents residual moisture in the rubber bale, plus any other volatile substances present — residual serum, fermentation products from the coagulation process, and processing aids.
The SIR20 maximum of 1.00% volatile matter ensures that rubber bales have been adequately dried before dispatch, reducing the risk of mold development during transit and storage and ensuring that the bale weight accurately represents dry rubber content. Rubber with volatile matter above 1.00% will lose additional weight during processing — the buyer effectively pays for water at the rubber price — and can cause processing problems including blistering and uneven vulcanization in rubber compound production.
Parameter 5: Plasticity Retention Index (PRI) — Min 60
The Plasticity Retention Index (PRI) is the most important functional specification parameter for natural rubber and the one that most directly relates to processing behavior and end-product performance. PRI measures the resistance of the rubber to oxidative degradation — specifically, the ratio of Wallace Plasticity after artificial aging (30 minutes at 140 degrees Celsius in a circulating air oven) to the initial unaged Wallace Plasticity Po, expressed as a percentage.
Why PRI Matters
A higher PRI indicates that the rubber retains its plasticity (and therefore its processing characteristics) better during heat exposure — which occurs during compound mixing, calendering, extrusion, and vulcanization in the rubber manufacturing process. Low PRI rubber degrades faster during processing, requiring adjustments to compound formulation and processing parameters and potentially yielding lower performance in the finished product. The SIR20 minimum PRI of 60 means the aged rubber retains at least 60% of its original plasticity after the 140-degree aging test — ensuring adequate processing stability for standard industrial applications.
PRI is influenced primarily by the antioxidant content of the rubber and by storage and handling conditions before and during processing. Rubber that has been exposed to excessive heat, light, or atmospheric pollution during storage may have degraded PRI even if it was originally above specification. Buyers should ensure that SIR20 bales are stored in covered, ventilated warehouses away from direct sunlight and heat sources to preserve PRI through to the point of use in production.
Parameter 6: Wallace Plasticity Po — Min 30
Wallace Plasticity Po measures the initial hardness and consistency of the unaged rubber using a Wallace Rapid Plastometer — a device that compresses a standard-sized rubber disc under a defined load at 100 degrees Celsius and measures the remaining thickness after 15 seconds of compression. The result (Po value) reflects the consistency and viscosity of the rubber before aging.
A minimum Po of 30 ensures that the SIR20 rubber has adequate molecular weight and viscosity for processing on standard rubber processing equipment. Rubber that is too soft (very low Po) is difficult to process — it sticks to mixing equipment, has poor dimensional stability during calendering and extrusion, and requires careful processing parameter adjustment. The minimum Po of 30 establishes a baseline processing consistency that is compatible with standard industrial rubber processing equipment without special adjustment.
Complete SIR20 Specification Reference Table
| Parameter | SIR5 | SIR10 | SIR20 | Test Method |
|---|---|---|---|---|
| Dirt Content (max) | 0.05% | 0.10% | 0.20% | ISO 249 |
| Ash Content (max) | 0.50% | 0.75% | 1.00% | ISO 247 |
| Nitrogen Content (max) | 0.60% | 0.60% | 0.60% | ISO 1656 |
| Volatile Matter (max) | 0.80% | 0.80% | 1.00% | ISO 248 |
| PRI (min) | 60 | 60 | 60 | ISO 2930 |
| Wallace Plasticity Po (min) | 30 | 30 | 30 | ISO 2007 |
| DRC (min) | 99% | 99% | 99% | ISO 248 / 247 |
Packaging Specification: 33.3 kg Bale Format
SIR20 is exported in the internationally standardized 33.3 kg bale format — this specific bale weight is the SICOM-aligned standard for TSR20-equivalent grades globally and is the format used by all major Indonesian rubber processing factories for export production. The 33.3 kg bale weight is not arbitrary — it represents exactly one-thirtieth of one metric ton (1,000 kg / 30 = 33.33 kg), which simplifies weight calculation and invoice preparation for buyers who work in metric ton units.
Bale Construction
Each SIR20 bale is formed by compressing crumb rubber — the granulated rubber produced in the crumbing and drying stage of SIR processing — under hydraulic pressure in a bale press mold. The compressed bale is wrapped in a thin polyethylene film that protects the bale surface from contamination and dust during storage and transit while remaining permeable enough to allow any residual volatile matter to escape. The polyethylene wrapping does not require removal before use in rubber compound production — the bale wrapping material is compatible with standard rubber compounding processes and is incorporated into the compound in negligible quantities that do not affect compound properties.
Pallet Configuration
Bales are stacked on standard wooden pallets in a defined configuration — typically 36 bales per pallet in a 4 x 3 x 3 arrangement (4 bales wide x 3 bales deep x 3 layers high), producing a pallet net weight of 36 x 33.3 kg = 1,198.8 kg per pallet. The pallet configuration is standardized to enable consistent forklift handling and to fit the internal dimensions of standard 20ft and 40ft dry containers in the most space-efficient arrangement.
Bale Dimensions
Standard SIR20 bale dimensions are approximately 67 cm x 33 cm x 18 cm — a flat rectangular form that stacks efficiently in both pallet and container configurations. The relatively flat profile (18 cm height) allows 3-layer pallet stacking within the standard container internal height without the top layer exceeding safe stacking limits.
Container Capacity: Detailed Guide for 20ft and 40ft
Container capacity for palletized SIR20 bales is more precisely predictable than for bulk-stacked commodities because the standardized bale weight, pallet configuration, and palletized loading method produce consistent fill weights across shipments. This predictability simplifies production planning and container booking for buyers with regular procurement schedules.
20ft Standard Dry Container
A standard 20-foot dry container has internal dimensions of approximately 5.90 m x 2.35 m x 2.39 m — approximately 33.0–33.2 cubic meters of usable internal volume. Loaded with palletized SIR20 bales in the standard 36-bale per pallet configuration, a 20ft container typically accommodates 16–17 pallets, yielding a net product weight of approximately 19.2–20.4 MT (approximately 580–612 bales). The standard reference is 600 bales / 20 MT net weight per 20ft container — used for planning purposes and consistent with the SICOM delivery specification for TSR20.
40ft Standard Dry Container
A standard 40-foot dry container with internal dimensions of approximately 12.03 m x 2.35 m x 2.39 m provides approximately 67.5 cubic meters of usable volume — accommodating approximately 33–34 pallets of palletized SIR20. Net product weight per 40ft container: approximately 660 bales / 22 MT. The 40ft container provides marginally better economics on a per-kilogram basis than two 20ft containers for buyers who can accept a single 40ft delivery — the container freight for a 40ft unit is typically 60–70% of two 20ft containers, reducing freight cost per MT of rubber by approximately 15–25% depending on route.
40ft High Cube Container
The 40ft high cube provides 30 cm additional internal height versus the standard 40ft, enabling an additional bale layer in some pallet configurations. Net product weight per 40ft high cube: approximately 700–720 bales / 23–24 MT. The incremental weight advantage versus standard 40ft is modest (approximately 1–2 MT) but can be meaningful at current SIR20 price levels where each additional MT of product represents USD 1,920–2,160 of FOB value.
Container Capacity Reference Table
| Container Type | Pallets | Bales | Net Weight | FOB Value* |
|---|---|---|---|---|
| 20ft Standard | 16–17 | ~600 | ~20 MT | ~USD 38,400–43,200 |
| 40ft Standard | 33–34 | ~660 | ~22 MT | ~USD 42,240–47,520 |
| 40ft High Cube | 35–36 | ~700–720 | ~23–24 MT | ~USD 44,160–51,840 |
* FOB value calculated at USD 1.92–2.16/kg. Actual value confirmed in proforma invoice at agreed FOB price per the SICOM TSR20 reference at time of order. Net weight confirmed in Packing List upon container loading.
Export Documentation for SIR20 Shipments
Every SIR20 export shipment from Indonesia requires a defined set of documents that enable import clearance at destination and provide the buyer with quality and compliance verification for their procurement records. The documentation package for rubber is distinct from food and agricultural commodity exports — notably, Phytosanitary Certificate is not required for processed rubber bales, as rubber is classified as a processed industrial material rather than a plant product at the point of export.
Standard Documentation Included
Certificate of Analysis (TSNR CoA): The most important quality document for SIR20 — covers all six TSNR specification parameters (dirt, ash, nitrogen, volatile matter, PRI, Po) tested by an accredited laboratory to the relevant ISO test methods. The CoA is the primary quality verification document used by the buyer's QA team to confirm specification compliance before the shipment is accepted into production inventory.
Certificate of Origin (COO): Issued by KADIN Indonesia or the Ministry of Trade, confirming Indonesian origin of the rubber for import duty and FTA preferential rate purposes. Critical for buyers importing into markets where ASEAN FTA rates apply — particularly China (ASEAN-China FTA, 0% duty for HS 4001.22) and India (AIFTA concessional rates).
Commercial Invoice and Packing List: Specifying the net weight per pallet and per container, number of bales, SICOM reference price, agreed FOB price per kilogram, and total FOB value.
Bill of Lading: The transport document issued by the shipping line confirming receipt of the goods for shipment and specifying the delivery terms.
Optional Documentation
Third-Party Pre-Shipment Inspection: SGS or Bureau Veritas inspection covering bale count verification, bale weight sampling, visual condition check, and sampling for independent TSNR laboratory testing. Available on request at buyer's cost — recommended for first-time purchases from a new exporter and for large-volume orders where independent quality assurance is part of the buyer's procurement compliance requirement.
EUDR Compliance Documentation: For buyers supplying EU markets — geolocation data for source plantation areas, deforestation-free satellite verification, and supply chain due diligence documentation as required by EU Deforestation Regulation. This documentation is becoming a standard requirement for EU market rubber supply and should be confirmed with the export partner as a supplier qualification criterion.
Receiving and Storage Guidelines for SIR20 Bales
Proper storage of SIR20 bales from arrival at the buyer's facility to point of production use protects the quality parameters confirmed in the CoA and ensures that the rubber performs as specified in compound production.
SIR20 bales should be stored in a covered, ventilated warehouse away from direct sunlight, heat sources above 35 degrees Celsius, and ozone-generating equipment (electric motors, high-voltage equipment). Exposure to elevated temperature, UV light, or ozone accelerates oxidative degradation of the rubber polymer and reduces PRI — the most quality-sensitive of the six specification parameters. Storage on pallets off the warehouse floor is recommended to allow air circulation and prevent moisture absorption from ground contact.
Natural rubber bales should not be stored adjacent to strongly flavored or odorous materials — rubber can absorb volatile compounds from the environment that may affect compound odor in finished products, particularly in automotive interior and consumer goods applications where odor is a quality criterion. Recommended maximum storage period before use in production: 12 months from date of manufacture under standard warehouse conditions.
For full product details, current FOB pricing, and documentation scope, visit our natural rubber SIR20 product page. As a reliable supplier spice and agricultural commodity exporter from Indonesia, Global Spice Trade provides complete TSNR CoA documentation and pre-shipment quality assurance on every SIR20 shipment.
Request SIR20 Specification Sheet & Current FOB Price
Contact our export team for the full TSNR SIR20 specification sheet, current FOB price based on today's SICOM TSR20 reference, and pre-shipment sample bale dispatch. We respond within 24 hours with a complete proforma including SICOM reference, basis differential, net weight per container, and full CoA scope. MOQ 1 x 20ft container (~20 MT / ~600 bales).
Request SIR20 Spec Sheet via WhatsApp →Frequently Asked Questions — Natural Rubber SIR20 Specification & Container Capacity
What are the six technical parameters in the SIR20 specification and their limits?
The six mandatory TSNR parameters for SIR20 are: (1) Dirt Content — max 0.20% (ISO 249); (2) Ash Content — max 1.00% (ISO 247); (3) Nitrogen Content — max 0.60% (ISO 1656); (4) Volatile Matter — max 1.00% (ISO 248); (5) Plasticity Retention Index (PRI) — min 60 (ISO 2930); (6) Wallace Plasticity Po — min 30 (ISO 2007). Dry Rubber Content (DRC) minimum 99% is additionally specified. All six parameters must be reported in the Certificate of Analysis from an accredited testing laboratory on every shipment.
Why is PRI the most important SIR20 parameter for compound manufacturers?
PRI (Plasticity Retention Index) directly measures resistance to oxidative degradation — the property most relevant to processing behavior during compound mixing, calendering, and vulcanization. Low PRI rubber degrades faster during processing heat exposure, requiring formulation adjustments and potentially yielding lower performance in the finished product. Unlike dirt or ash content which are stable for a given processing source, PRI can vary with storage conditions and seasonal factors. Buyers should require PRI testing on every shipment CoA and track PRI values across successive lots to monitor supply quality consistency.
How many bales and what net weight fit in a 20ft container of SIR20?
A standard 20ft dry container loaded with palletized SIR20 bales (33.3 kg each, 36 bales per pallet) holds approximately 16–17 pallets and approximately 600 bales, achieving a net product weight of approximately 20 MT. A 40ft container holds approximately 660 bales at 22 MT net. A 40ft high cube holds approximately 700–720 bales at 23–24 MT net. These are planning reference figures — actual net weight is confirmed in the Packing List upon container loading.
What is DRC and how does it affect the effective cost of SIR20?
DRC (Dry Rubber Content) is the percentage of actual dry rubber polymer in the bale — minimum 99% for SIR20. This means at least 99% of the bale weight is pure rubber polymer. A lot with DRC of 97% contains 2% less usable rubber per kilogram purchased compared to 99% DRC at the same FOB price — effectively increasing your true cost per kilogram of dry rubber by approximately 2%. Always confirm DRC is minimum 99% in the CoA for each shipment to ensure consistent rubber content per kilogram purchased.
Does the polyethylene bale wrapping need to be removed before use in compounding?
No. The thin polyethylene film wrapping on SIR20 bales does not require removal before use in standard rubber compound production. The PE film is incorporated into the compound in negligible quantities — typically less than 0.1% by weight — that do not materially affect compound properties for standard tire and industrial rubber applications. Some compound formulations for very demanding applications or specific customer specifications may require PE-free input rubber — if this applies to your application, confirm with your compound chemist before ordering PE-wrapped SIR20.
What is the recommended storage period for SIR20 bales?
Maximum recommended storage period is 12 months from date of manufacture under standard warehouse conditions — covered, ventilated, below 35 degrees Celsius, away from direct sunlight, UV sources, and ozone-generating equipment. Longer storage increases the risk of PRI degradation from slow oxidative aging even under proper conditions. First-in-first-out (FIFO) inventory management is recommended to ensure older stock is used before newer receipts. If storage beyond 12 months is required, retest PRI before use in production to confirm the rubber still meets specification.
Is SIR20 from Indonesia compliant with EUDR for European buyers?
Indonesian SIR20 from established estates and cooperatives that have not undergone deforestation after December 31, 2020 can comply with EUDR requirements. Compliance requires geolocation data for source plantation areas, deforestation-free verification from approved satellite monitoring services, and supply chain due diligence documentation. Not all Indonesian exporters have completed the systems and documentation required for full EUDR compliance — buyers sourcing for EU markets should confirm EUDR capability as a supplier qualification requirement before committing to a supply relationship. Contact our team to discuss EUDR compliance documentation availability for your specific order.
No comments