---
title: "Cork — density, melting point and properties"
description: "Cork has a density of 200 kg/m³ (120–240). Melting point, strength, conductivity, what it is used for, and whether it floats, rusts or is magnetic."
url: https://atoneplace.net/material/cork/
site: "At One Place"
---

# 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

*Water is 1,000 kg/m³. Anything below that floats.*

| 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?](https://atoneplace.net/does-it-float/cork/)
- [Air](https://atoneplace.net/material/air/)
- [Ice](https://atoneplace.net/material/ice/)
- [Paper](https://atoneplace.net/material/paper/)
- [Corrugated cardboard](https://atoneplace.net/material/cardboard/)
- [Leather](https://atoneplace.net/material/leather/)

## Sources

- Typical range compiled from manufacturer specifications — At One Place (/about/)