What's the best way to remove rust from an old file?

[rickmenefee]

Im sorry I thought you were trying to get more use out of the file. Disregard my prevails post.

 

[Hankins]

Actually 10% molassas / water mix will work and not remove metal.
Personally have used http://www.boggstool.com/ as 12345678910 suggests excellent results.
Most of the rust if not all will come off in HT anyway