Rust Is Iron Returning to Its Natural State
Rust is the reddish coating formed on iron. Chemically it is the metal going back to ore.
Rust is the flaky reddish-brown coating that forms on iron exposed to air and moisture. It is the metal returning to the form it was mined in: iron ore is largely iron oxide, smelting removes the oxygen at great cost in fuel, and rusting simply gives it back. Every rusting object is undoing a furnace. Rust is also why iron corrodes through while aluminium does not: aluminium oxide forms a tight sealing layer, whereas rust flakes away and exposes fresh metal beneath.
- Iron oxide. *Covered in rust.*
- To corrode. *The gate rusted.*
- A plant disease. *Wheat rust.*
- A reddish colour. *Rust brown.*
- Old English — *rust*. *The source.*
Word forms
| Form | Word | Example |
|---|---|---|
| Noun | rust | Rust. |
| Verb | rust | Rusting. |
| Adjective | rusty | Rusty. |
| Compound | rustproof | Rustproof. |
| Related | red | Red. |
- The hinges were rusty.Metal.
- Ore is largely iron oxide.Chemistry.
- Wheat rust destroyed the crop.Disease.
Why some metals resist
- Iron — rust flakes off, exposing fresh metal underneath
- Aluminium — forms a tight oxide layer that seals the surface
- Stainless steel — chromium forms a similar protective film
- Copper — develops a green patina that protects it
- Galvanising — a zinc coat corrodes in place of the iron
Old English *rust*, of Germanic origin, related to *red*.
Why does iron rust through but aluminium does not?
Rust flakes away and exposes fresh metal, while aluminium oxide forms a tight layer that seals the surface.
Is rusting the opposite of smelting?
Essentially yes. Smelting strips oxygen from iron ore, and rusting puts it back.