---
title: "Epoxy resin — density, melting point and properties"
description: "Epoxy resin has a density of 1,150 kg/m³ (1,100–1,250). Melting point, strength, conductivity, what it is used for, and whether it floats, rusts or is magnetic."
url: https://atoneplace.net/material/epoxy-resin/
site: "At One Place"
---

# Epoxy resin

**Density of epoxy resin: 1,150 kg/m³ (1,100–1,250)**

1.15 g/cm³ · 71.8 lb/ft³

A thermoset: once the resin and hardener have cross-linked, there is no melting point and no going back — heat it far enough and it chars. It shrinks less than a percent on curing, against 6-8% for polyester resin, which is why it bonds and laminates so much better and why aircraft composites use it. Cure is chemistry, not drying, so it needs the right ratio by weight and it needs warmth: below about 15 °C many epoxies never fully harden and stay permanently tacky.

## Properties

- **Density:** 1,150 kg/m³ (1,100–1,250) — 1.15 g/cm³
- **Tensile strength:** 40–90 MPa
- **Young's modulus:** 3 GPa
- **Thermal conductivity:** 0.2 W/(m·K)
- **Thermal expansion:** 60 µm/(m·K)
- **Floats in water:** No
- **Magnetic:** No

## What it is used for

- Composite laminating matrix
- Structural adhesives and anchors
- PCB substrate (as FR-4)
- Floor coatings and river tables

## 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
- Water — the float line: 1,000 kg/m³
- epoxy resin: 1,150 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× |
| epoxy resin ← | 1,150 kg/m³ | 1.15× |
| platinum | 21,450 kg/m³ | 21.45× |
| gold | 19,300 kg/m³ | 19.30× |
| tungsten | 19,250 kg/m³ | 19.25× |

## Does it rust?

Epoxy resin contains no iron, so it cannot rust. Whether it degrades depends on the material, not on oxidation.

## Is it magnetic?

Epoxy resin is not a metal and has no ferromagnetic response.

## Common questions

### What is the density of epoxy resin?

1,150 kg/m³ (1,100–1,250), or 1.15 g/cm³.

### Does epoxy resin float?

No. At 1,150 kg/m³ it is denser than water.

### Is epoxy resin magnetic?

Epoxy resin is not a metal and has no ferromagnetic response.

## Related pages

- [Does epoxy resin float?](https://atoneplace.net/does-it-float/epoxy-resin/)
- [PLA](https://atoneplace.net/material/pla/)
- [ABS](https://atoneplace.net/material/abs/)
- [Acrylic (PMMA)](https://atoneplace.net/material/acrylic/)
- [Polycarbonate](https://atoneplace.net/material/polycarbonate/)
- [Polypropylene](https://atoneplace.net/material/polypropylene/)
- [PTFE](https://atoneplace.net/material/ptfe/)
- [Rigid PVC](https://atoneplace.net/material/pvc-rigid/)
- [HDPE](https://atoneplace.net/material/hdpe/)

## Sources

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