# Chemically removing rust without leaving any unwanted residues

I have this iron pan that got rusty from not being properly dried. Scrubbing it I was able to get rid of most of the rust, but there's still some I just can't remove. I thought I could chemically remove it, but I myself am a bit rusty on the inorganic chemistry subject, so I couldn't think of any way of doing it without leaving any unwanted residue on the pan.

The rust is the brownish-red type, which according to Wikipedia consists of $\ce {Fe2O3·nH2O}$ and $\ce{FeO(OH)·Fe(OH)3}$. Most rust-removal "recipes" I found involve all sorts of acids, but I can't tell what the reaction(s) would be with $\ce {Fe2O3·nH2O}$ so I can't tell if there would be any residues left behind that I could not remove. Anyone with any experience on the matter?

I contacted the manufacturer and the pan is hand-made, just Iron and natural coating (fat).

• After you remove the rust, dry out the pan on a hot burner on the stove after washing. This will prevent future rust. You have to keep a close eye on it so you can remove it from heat as soon as it is dry. – user20721 Sep 8 '15 at 15:05
• I would emphasize that for an iron pan, you need to re-coat "season" before drying to prevent rust. Otherwise moisture from the air will eventually start to rust the pan again. – Geoff Hutchison Sep 8 '15 at 16:24

The common DIY rust remover is cola of some sort -- most colas contain a significant quantity of phosphoric acid, which reacts with the iron oxide to form iron (III) phosphate which you can then scrub off. Any remaining iron phosphate should come off with time and/or more water, and is harmless in domestic quantities.

• ...and a third option would be citric acid (citrus juices). – buckminst Apr 19 '13 at 20:37

Oxalic acid or citric acids works just fine and are not too toxic (I tested oxalic acid myself, it works great! much better, then most mineral acids) . It is preferable to not use strong mineral acids as they will eat some iron too (in fact, they have problems dissolving iron (III) oxide in acceptable time), and oxalic and citric acids are not strong, but gives complexes with iron ions and dissolves rust just fine. Acetic acid cannot give complexes, so I wouldn't bet on it.

If you're worried about residues, just use a common kitchen item that is acidic. Vinegar is just acetic acid. That should do the trick.

## protected by Community♦Oct 28 '15 at 4:54

Thank you for your interest in this question. Because it has attracted low-quality or spam answers that had to be removed, posting an answer now requires 10 reputation on this site (the association bonus does not count).