How To Clean Concrete Basement Floor Before Staining. A solution of tsp (trisodium phosphate) and a lot of elbow grease with a scrub brush would be your best bet. Acid washing depletes the lime content in the concrete, which is what the minerals in the acid stain react with to develop color.
Allow the surface to dry completely before proceeding with acid staining. Another option would be to use a pressure washer to clean the concrete slab.
Apply citrus degreaser to a small part of your basement floor with your scrub brush. Apply your floor polisher to the area and scrub it.