I'm trying to figure out how to make pure rust (Fe2O3). Using electrolysis in salt you can make rust, but you also get some Iron (II) Hydroxide which makes it impure- how do I know this, I tried it and my solution looked like this: File:Ferrous hydroxide.JPG - Wikipedia, the free encyclopedia so I'm certain it's impure. Putting Iron in water and just waiting also makes pure rust but it takes a long time. I tried burning iron wool with a 9 volt battery but it didn't turn it into rust (it turned it more grey), I might be able to make it rust by getting a source of pure oxygen near the flaming wool and letting it rust, but I don't have the equipment for a really complicated setup. Can anyone think of an ingenious and simple method to create pure rust in relatively short period of time?