After 30 minutes you will want to lightly scrub the rusty surface.
Rust removal floor pan.
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.
The baking soda will help wick up and remove rust that is in the pan.
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.
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.
Alternatively soak the pan overnight in a solution of water.
To remove the old grease and waxoyl i have used bits of the old carpet and cut into rectangles sort of five by seven inches or so.
Then make sure you properly seal the floor pans.
Patch panel rust repair full floor pan vs partial floor pan.
The front where the pedals are the middle under and behind the front seats then the section under the rear seats.
The floor pan is such a large area i had to tackle it in three sections.