Rubber and elastomer compounds, formulated to spec
Natural rubber, NBR, EPDM, FKM, silicone, HNBR and TPE compounds — formulated by audited Chinese mixers for sealing, vibration, tire and dynamic applications, with COA per batch.
Rubber sourcing is compound sourcing
Rubber and elastomer materials are rarely sold as raw polymer. They are sold as compounds — a base elastomer plus carbon black or silica reinforcement, plus plasticisers, antioxidants, accelerators and a curing system, all mixed and milled into a consistent feedstock for moulding or extrusion. Two compounds with the same elastomer base can perform very differently because of their additive package and mix history.
Sourcing Captain places rubber orders against a compound spec, not just a polymer name. The compound spec includes hardness, tensile strength, elongation at break, compression set, oil and chemical resistance, temperature range and any application-specific test (low-temperature flexibility, ozone resistance, fluid compatibility). We work with Chinese rubber mixers who are willing to formulate to the buyer's spec and to lock the recipe.
The category we cover spans natural rubber and SBR for tires and general products, NBR and HNBR for oil-resistant sealing, EPDM for weather and steam, FKM and FFKM for chemical resistance, silicone for high temperature and food contact, and TPE/TPV for processable thermoplastic elastomers.
Rubber sourcing — six steps
Compound spec
Hardness, tensile, elongation, compression set, temperature range and any application test written into a single document.
Mixer shortlist
Two or three audited Chinese rubber mixers willing to lock the recipe.
Sample slab
A sample slab cured to the supplier's recommendation for full physical and ageing testing.
Recipe lock
Locked recipe (Master Batch + Final Batch) referenced in the PO — no silent substitutions.
Bulk PO
Locked-price PO with COA per batch and an inspection clause.
Release & ship
Per-batch COA and PSI report issued before shipment.
Per-batch deliverables
COA
Per-batch COA with hardness, tensile, elongation, compression set and any application test.
Recipe reference
Internal recipe lock reference confirming no substitution from the agreed formulation.
Cure chart
Recommended cure schedule from the mixer for the supplied compound.
Sample retain
Cured sample slab held for 12 months in our China warehouse.
PSI report
Pre-shipment inspection of bales, slabs or strips before container loading.
Sourcing dossier
Mixer audit, supplier and per-batch data bundled into a single PDF.
Why "the same compound" is rarely the same
The most common rubber sourcing failure is silent recipe drift. A mixer who is asked for "EPDM 70 shore A" and not given a written compound spec will hit the hardness number with whatever filler and accelerator package they have on hand — and the compound that arrives next month may have different compression set or different ageing performance from the one that arrived last month. Downstream, that shows up as a sealing line that suddenly fails on field test.
A sourcing partner who locks the recipe by spec, takes a sample at PO, and verifies per-batch COA against the original is the difference between repeatable supply and a quietly drifting one. Global buyers who run rubber compounds across thousands of moulded parts know how expensive that drift is.
Rubber & elastomer FAQs
Which elastomer families do you cover?
Natural rubber, polyisoprene, polybutadiene, SBR, NBR, HNBR, EPDM, IIR/CIIR/BIIR (butyl), CR (chloroprene), CSM (Hypalon), FKM and FFKM, silicone (VMQ, FVMQ, PMQ), polyurethane (TPU and cast PU) and thermoplastic elastomers (SBS, SEBS, TPV, TPO, COPE).
Can you supply compounded slab or rolled stock?
Yes, we ship as compound slab, sheet stock, calendered sheet, extruded profile or pre-cut blanks for moulding. Format is part of the PO and is signed off at sample stage.
Do you handle FDA / food contact silicone?
Yes — FDA 21 CFR 177.2600 silicone compounds, with the food contact statement as part of the per-batch documentation.
How small is your minimum order?
Most compounds ship from 500 kg, with full container loads of 8–20 tonnes for high-volume buyers. Specialty FKM and FFKM compounds can ship from 50 kg with a longer lead time.
How long is the typical lead time?
4–8 weeks from PO for standard compounds, 8–12 weeks for build-to-order specialty formulations. We confirm a binding lead time at PO time.
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Tell us what you need to source
Send specs, target volumes, and timelines. Our sourcing team replies within one business day with a sourcing plan and price guidance.