Natural Cork CR (Cold rolled)
Supply condition
Choose for oil-resistant gaskets, transformer and machine-mount pads where higher strength, sealing and fluid resistance are needed.
Values for the CR condition
Other Natural Cork tempers and conditions
Natural Cork is listed in 3 conditions; see the grade overview at Natural Cork.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Expanded (black) insulation corkboard, steam-expanded, binder-free | Choose for thermal/acoustic insulation and cryogenic pipe supports — lowest conductivity, self-bonded by its own resins, no added binder. | — | 0.08 | — | — | 0.04 W/m·K |
Agglomerated (composition) cork, granules + resin binder | Choose for sheets, gasket stock, floor underlay and cork boards where large uniform panels and low cost matter more than pure elasticity. | — | 0.8 | 5 | — | 0.06 W/m·K |
CRThis page Cold rolled | Choose for oil-resistant gaskets, transformer and machine-mount pads where higher strength, sealing and fluid resistance are needed. | — | 3 | 25 | — | 0.1 W/m·K |
What is Natural Cork CR?
Natural Cork CR is Natural Cork supplied in the CR condition — choose for oil-resistant gaskets, transformer and machine-mount pads where higher strength, sealing and fluid resistance are needed. Natural Cork CR has a tensile strength of 3 MPa (0.363 ksi), weaker than 89% of natural material grades. Elongation at break is 25% and the elastic modulus is 0.03 GPa (0.0044 Msi). Natural Cork CR has a density of 0.85 g/cm³ (0.0307 lb/in³), heavier than 70% of natural material grades.
Advantages
- Ductile — tolerates forming and impact — 25%, better than 89% of natural material grades
- High service temperature — 120°C (248 °F), better than 79% of natural material grades
- Low embodied carbon — 0.3 kg CO₂/kg, better than 79% of natural material grades
- Good corrosion resistance — 70/100, better than 78% of natural material grades
Limitations
- Hard to polish — 10/100, worse than 99% of natural material grades
- Low stiffness — 0.03 GPa (0.0044 Msi), worse than 89% of natural material grades
- Poor heat conductor — 0.1 W/m·K (0.0578 BTU/hr·ft·°F), worse than 84% of natural material grades
Natural Cork CR properties
Typical room-temperature values for Natural Cork CR; 11 are specific to this condition. Other listed values are Natural Cork reference data and may not represent this condition. Bars are the position among natural material grades.
Physical2
Natural Cork CR has a density of 0.85 g/cm³ (0.0307 lb/in³), heavier than 70% of natural material grades.
Mechanical9
Natural Cork CR has a tensile strength of 3 MPa (0.363 ksi), weaker than 89% of natural material grades. Elongation at break is 25% and the elastic modulus is 0.03 GPa (0.0044 Msi).
Thermal4
Natural Cork CR is rated for continuous service to 120°C (248 °F). It conducts heat at 0.1 W/m·K (0.0578 BTU/hr·ft·°F), worse than 84% of natural material grades.
Electrical1
Natural Cork CR has an electrical resistivity of 1×10¹¹ Ω·m.
Chemical & Environmental1
Corrosion resistance is very good (70/100), better than 78% of natural material grades.
Sustainability4
Producing a kilogram of Natural Cork CR takes about 5 MJ of energy and emits 0.3 kg of CO₂ — less than 81% of natural material grades. Typical recycled content is 60%.
Manufacturability2
Natural Cork CR's machinability is very good (75/100, worse than 60% of natural material grades).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Natural Cork CR
Is Natural Cork easy to machine?
Die-cut, punched, band-sawn or laser-cut with sharp tooling and high speed; dust extraction required, no coolant.
Can Natural Cork be welded?
Not weldable — join by contact adhesive, PU/PVAc glue or hot-melt; agglomerates are heat-pressed with resin.
Can Natural Cork be formed, bent or molded?
Granules are compression-moulded with binder or steam-expanded in autoclave blocks, then sliced into sheet or profile.
What surface finishes work on Natural Cork?
Sand lightly and seal with wax, PU or water-based lacquer; cannot be polished, surface will stay porous.
Natural Cork chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| suberincross-linked fatty-acid polyester of the cell wall | 33 – 50 | 42 |
| lignin | 18 – 26 | 22 |
| polysaccharides (cellulose + hemicellulo | 12 – 25 | 19 |
| extractives (waxes, tannins) | 8 – 20 | 15 |
| ash + moisturebalance, varies with equilibrium moisture | ≥ 1 (balance) | — |
Natural Cork CR — frequently asked
What is Natural Cork CR used for?
Natural Cork CR is typically used for gaskets, bottle stoppers, flooring underlayment, vibration isolation pads and bulletin boards. In short: lowest-density natural gasket material; best natural vibration damping; closed-cell, non-rotting.
What is the tensile strength of Natural Cork CR?
Natural Cork CR has a typical tensile strength of 3 MPa (0.363 ksi) — weaker than 89% of natural material grades. Strength varies by condition: see the 3 listed tempers.
Is Natural Cork CR easy to machine?
Yes — machinability is rated very good (75/100, worse than 60% of natural material grades). Die-cut, punched, band-sawn or laser-cut with sharp tooling and high speed; dust extraction required, no coolant.
Can Natural Cork CR be welded?
Not weldable — join by contact adhesive, PU/PVAc glue or hot-melt; agglomerates are heat-pressed with resin.
What surface finishes work on Natural Cork CR?
Sand lightly and seal with wax, PU or water-based lacquer; cannot be polished, surface will stay porous.
Can Natural Cork CR be formed, bent or molded?
Granules are compression-moulded with binder or steam-expanded in autoclave blocks, then sliced into sheet or profile.
What is the maximum service temperature of Natural Cork CR?
Natural Cork CR is rated for continuous use to about 120°C (248 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- Cellular Solids: Structure and Properties, 2nd ed. — Cambridge University Press (Gibson & Ashby) (1997)
- Cork: properties, capabilities and applications (Int. Materials Reviews 50) — Taylor & Francis (Silva et al.) (2005)
- EN 13170 — Thermal insulation products: factory made expanded cork (ICB) — CEN (2012)
- ASTM F104 — Classification System for Nonmetallic Gasket Materials (cork and cork-rubber) — ASTM (2018)
- Amorim Cork Composites technical data sheets (agglomerated, expanded, cork-rubber) — Corticeira Amorim (2023)
- Materials and the Environment (embodied energy/CO2 of natural materials) — Butterworth-Heinemann (Ashby) (2021)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.