Pour vinegar on the stain to completely cover the area. Choose either white or apple cider vinegar.
Let the vinegar sit on the stain for 20 minutes.
Repeat pouring vinegar on the stain and let it sit for another 20 minutes.
Scrub the stain with a scrub brush. Choose a synthetic-bristled brush so you won’t scratch the Diamond Brite.
Scrub vigorously in a back-and-forth and up-and-down motion.
Rinse the vinegar from the Diamond Brite with clean water. If the vinegar did not remove the stain, proceed to Step 5.
Put on rubber gloves. Pour an oxalic acid cleaner on an inconspicuous area of the Diamond Brite.
Let the solution sit on the surface according to package directions. Check the area to make sure the acid did not damage the surface.
Pour oxalic acid cleaner on the stain. Let the acid sit on the stain according to package directions.
Scrub the stain with the scrub brush. Rinse the acid from the Diamond Brite surface, being careful to completely remove the acid.
Use a wet-dry vacuum to remove all of the water.