Rust is an iron oxide, usually red oxide formed by the redox reaction of iron and oxygen in the presence of water or air moisture. Several forms of rust are distinguishable both visually and by spectroscopy, and form under different circumstances. Rust consists of hydrated iron(III) oxides Fe2O3·nH2O and iron(III) oxide-hydroxide (FeO(OH), Fe(OH)3).
Given sufficient time, oxygen, and water, any iron mass will eventually convert entirely to rust and disintegrate. Surface rust is flaky and friable, and it provides no protection to the underlying iron, unlike the formation of patina on copper surfaces. Rusting is the common term for corrosion of iron and its alloys, such as steel. Many other metals undergo similar corrosion, but the resulting oxides are not commonly called rust.
Other forms of rust exist, like the result of reactions between iron and chloride in an environment deprived of oxygen. Rebar used in underwater concrete pillars, which generates green rust, is an example. Although rusting is generally a negative aspect of iron, a particular form of rusting, known as "stable rust," causes the object to have a thin coating of rust over the top, and if kept in low relative humidity, makes the "stable" layer protective to the iron below, but not to the extent of other oxides, such as aluminum.

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  1. 6gunslinger

    Beretta 81 surplus influx info...

    Recently Classic firearms and AIM surplus and a few other places have got their hands on bulk quantities of police trade in Beretta 81 pistols chambered in .32 I got one from classic and can attest to its excellence in both hand fit and controllability. It would truly make an excellent carry gun...
  2. tlfreek


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  3. N Monty

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    Long story short- I went shooting in the rain a while ago, and thought I cleaned all my rifles. Realized recently that this one got missed, and immediately set to cleaning it. The barrel is looking kind of gross, and patches keep coming out filthy, but it seems like it's getting better. I'm...
  4. mikemenzie

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  5. Glock Jock

    Is this rust or copper fouling?

    I have only put 60 rounds through my Bergara .30-06, went shooting yesterday and waited until today to clean it only to find this rust/copper color in my barrel after cleaning it. I have used Hoppes #9 and Hoppes Copper remover with nylon and brass brushes. It stays the same and zero rust...
  6. h4344

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  7. Glock Jock

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  8. h4344

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  9. StacattoP

    Can anyone help 1911 rust issues!

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  10. MooThulhu

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