If it s just surface rust the most effective removal process is simply using a grinder with a wire wheel to clean up the old sheetmetal.
Rust removal floor pan.
The floor pan is such a large area i had to tackle it in three sections.
Take a sponge with a scrubber and scrub at all of the rust spots using the heavy duty scrubbing side.
Then make sure you properly seal the floor pans.
If you replace left and right side partial panels and leave the original tunnel intact you re welding about ten more feet of sheet metal versus replacing the whole floor.
If you want to remove rust from pots and pans use a gentle abrasive like salt that will scrape up the rust without damaging the metal.
Curiously replacing the full floor pan is actually less work than doing two partial panels.
Patch panel rust repair full floor pan vs partial floor pan.
After 30 minutes you will want to lightly scrub the rusty surface.
To scrape off the rust cover the bottom of the pan with a thin layer of salt and scrub it in using a brown paper bag until the rust is lifted off.
Alternatively soak the pan overnight in a solution of water.