Wet the sink with water from the tap.
Immediately sprinkle scouring powder over the entire surface of the sink. Let it sit for 10 minutes.
Wet a plastic scrubbing pad with water and scrub it over the entire surface of the sink. Pay special attention to scrubbing marks on the sink. Work until the marks are gone.
Rinse the sink with water from the tap and with water from a sponge.
Wipe the area with a cloth to remove water and cleaning solution residue from the edges around the sink and counter. Let the inside of the sink air dry.
Mix 1 cup bleach with 1 cup water.
Soak a clean cloth in the solution and lay it over the mark on the Swanstone sink. Let it sit for 10 minutes.
Remove the cloth and buff out the stains with it.
Rinse the Swanstone sink with water and dry it thoroughly with a clean cloth.