Cork
Density of cork
200 kg/m³ (120–240)
0.20 g/cm³ · 12.5 lb/ft³
The bark of the cork oak, harvested every nine years without felling the tree, and structurally a mass of sealed gas-filled cells — over 80% of its volume is trapped air. Its unusual property is a Poisson ratio near zero: squeeze it and it does not bulge sideways, which is precisely why a cork can be pushed into a bottle neck and a rubber bung cannot. That, plus its impermeability to liquid and its resilience, is why 500 years of alternatives have not displaced it.
Properties
- Density
- 200 kg/m³ (120–240) — 0.20 g/cm³
- Young's modulus
- 0.02 GPa
- Thermal conductivity
- 0.043 W/(m·K)
- Floats in water
- Yes
- Magnetic
- No
What it is used for
- Wine bottle stoppers
- Flooring and wall tiles
- Gaskets and vibration isolation pads
- Cricket and baseball cores, fishing floats
How it compares
Water is 1,000 kg/m³. Anything with a shorter bar than water floats in it.
air 1.2 kg/m³
expanded polystyrene foam 20 kg/m³
rigid polyurethane foam 40 kg/m³
cork 200 kg/m³
Water — the float line 1,000 kg/m³
tungsten 19,250 kg/m³
gold 19,300 kg/m³
platinum 21,450 kg/m³
| Material | Density | Relative to water |
|---|---|---|
| rigid polyurethane foam | 40 kg/m³ | 0.04× |
| expanded polystyrene foam | 20 kg/m³ | 0.02× |
| air | 1.2 kg/m³ | 0.00× |
| cork ← | 200 kg/m³ | 0.20× |
| platinum | 21,450 kg/m³ | 21.45× |
| gold | 19,300 kg/m³ | 19.30× |
| tungsten | 19,250 kg/m³ | 19.25× |
Does it rust?
Cork contains no iron, so it cannot rust. Whether it degrades depends on the material, not on oxidation.
Is it magnetic?
Cork is not a metal and has no ferromagnetic response.
Common questions
- What is the density of cork?
- 200 kg/m³ (120–240), or 0.20 g/cm³.
- Does cork float?
- Yes. At 200 kg/m³ it is less dense than water's 1,000.
- Is cork magnetic?
- Cork is not a metal and has no ferromagnetic response.
Related pages
- Does cork float? Yes
- Air 1.2 kg/m³
- Ice 917 kg/m³
- Paper 800 kg/m³
- Corrugated cardboard 160 kg/m³
- Leather 900 kg/m³
Sources
- Typical range compiled from manufacturer specifications — At One Place