Electrolysis? I know, electro... what? In very basic terms, electrolysis is a method to remove rust without using chemicals.
Don't be alarmed though: Cast iron is quite forgiving, so if it rusts, all you need is some Scotch-Brite steel wool, and you'll be back on track. To remove rust from your cast iron skillet ...
The combination of the acidic properties in the ketchup and gentle scrubbing will help to loosen and remove the rust from the ...