Cork CR (Cold rolled)
Supply condition
Cork granules in an elastomer matrix (ASTM F104 style) — pick for oil-resistant, high-recovery sealing gaskets and anti-vibration pads at higher clamp loads.
Values for the CR condition
Other Cork tempers and conditions
Cork is listed in 3 conditions; see the grade overview at Cork.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Expanded (black) cork insulation board, EN 13170 | Steam-expanded granules self-bonded by their own suberin resin — binder-free, dimensionally stable insulation board for walls, roofs and cryogenic linings. | — | 0.09 | — | — | 0.04 W/m·K |
Agglomerated (composition) cork, resin-bonded granules | Cork granules bonded with PU/phenolic binder into sheet, roll or block — the standard choice for gaskets, underlayment and low-cost boards with uniform properties. | — | 0.9 | 5 | — | 0.05 W/m·K |
CRThis page Cold rolled | Cork granules in an elastomer matrix (ASTM F104 style) — pick for oil-resistant, high-recovery sealing gaskets and anti-vibration pads at higher clamp loads. | — | 2 | 15 | — | 0.1 W/m·K |
What is Cork CR?
Cork CR is Cork supplied in the CR condition — cork granules in an elastomer matrix (ASTM F104 style) — pick for oil-resistant, high-recovery sealing gaskets and anti-vibration pads at higher clamp loads. Cork CR has a tensile strength of 2 MPa (0.319 ksi), weaker than 89% of natural material grades. Elongation at break is 15% and the elastic modulus is 0.02 GPa (0.0029 Msi). 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 — 15%, better than 86% of natural material grades
- Good corrosion resistance — 80/100, better than 84% of natural material grades
- High service temperature — 150°C (302 °F), better than 83% of natural material grades
Limitations
- Hard to polish — 12/100, worse than 94% of natural material grades
- Low stiffness — 0.02 GPa (0.0029 Msi), worse than 93% 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
Cork CR properties
Typical room-temperature values for Cork CR; 11 are specific to this condition. Other listed values are Cork reference data and may not represent this condition. Bars are the position among natural material grades.
Physical2
Cork CR has a density of 0.85 g/cm³ (0.0307 lb/in³), heavier than 70% of natural material grades.
Mechanical9
Cork CR has a tensile strength of 2 MPa (0.319 ksi), weaker than 89% of natural material grades. Elongation at break is 15% and the elastic modulus is 0.02 GPa (0.0029 Msi).
Thermal5
Cork CR is rated for continuous service to 150°C (302 °F). It conducts heat at 0.1 W/m·K (0.0578 BTU/hr·ft·°F), worse than 84% of natural material grades. Thermal expansion is 180 µm/m·K (100 µin/in·°F).
Electrical1
Cork CR has an electrical resistivity of 1×10¹¹ Ω·m.
Chemical & Environmental1
Corrosion resistance is very good (80/100), better than 84% of natural material grades.
Sustainability4
Producing a kilogram of Cork CR takes about 6 MJ of energy and emits 0.5 kg of CO₂ — less than 78% of natural material grades. Typical recycled content is 0%.
Manufacturability2
Cork CR's machinability is very good (70/100, worse than 67% of natural material grades).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Cork CR
Is Cork easy to machine?
Die-cuts, punches, waterjets and CNC-routs easily with very sharp tools and vacuum hold-down; avoid high tool temperatures that scorch the suberin.
Can Cork be welded?
Not weldable — join by contact adhesive, PU/phenolic binder or elastomer bonding; expanded board is also mechanically fixed.
Can Cork be formed, bent or molded?
Boiled planks are punched or sliced; granules are hot-pressed with binder (agglomerated) or steam-expanded and self-bonded in autoclaves (ICB blocks) then sawn to size.
What surface finishes work on Cork?
Sanding plus wax, shellac or PU sealer for floors; surfaces cannot be polished to gloss and stay porous unless sealed or rubber-faced.
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, source of elasticity and impermeability | 33 – 50 | 42 |
| lignin | 18 – 26 | 22 |
| polysaccharides (cellulose + hemicellulo | 12 – 25 | 19 |
| extractives (waxes, tannins, ceroids) | 8 – 20 | 14 |
| ash / inorganics | 0.5 – 2.5 | 1.2 |
| moisture (as supplied)equilibrium moisture, affects density and resistivity | 4 – 9 | 6 |
Cork CR — frequently asked
What is Cork CR used for?
Cork CR is typically used for bottle stoppers, gaskets and seals, flooring underlayment, insulation panels and vibration/noise damping. In short: lowest-modulus natural material; closed-cell and buoyant; strong natural damping.
What is the tensile strength of Cork CR?
Cork CR has a typical tensile strength of 2 MPa (0.319 ksi) — weaker than 89% of natural material grades. Strength varies by condition: see the 3 listed tempers.
Is Cork CR easy to machine?
Yes — machinability is rated very good (70/100, worse than 67% of natural material grades). Die-cuts, punches, waterjets and CNC-routs easily with very sharp tools and vacuum hold-down; avoid high tool temperatures that scorch the suberin.
Can Cork CR be welded?
Not weldable — join by contact adhesive, PU/phenolic binder or elastomer bonding; expanded board is also mechanically fixed.
What surface finishes work on Cork CR?
Sanding plus wax, shellac or PU sealer for floors; surfaces cannot be polished to gloss and stay porous unless sealed or rubber-faced.
Can Cork CR be formed, bent or molded?
Boiled planks are punched or sliced; granules are hot-pressed with binder (agglomerated) or steam-expanded and self-bonded in autoclaves (ICB blocks) then sawn to size.
What is the maximum service temperature of Cork CR?
Cork CR is rated for continuous use to about 150°C (302 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- Cellular Solids: Structure and Properties (cork chapter) — Cambridge University Press (1997)
- Cork: Biology, Production and Uses — Elsevier (2007)
- EN 13170 — Thermal insulation products: factory made expanded cork (ICB) — CEN (2012)
- ASTM F104 — Classification System for Nonmetallic Gasket Materials — ASTM (2021)
- Expanded cork insulation board technical data — Amorim Cork Insulation (2023)
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.