If aluminum is new or fairly new: metal could have a light oily coating from the manufacturing process. Clean with a citrus based degreaser, rinse thoroughly and dry. Scuff with P120 sandpaper, dust and ready to apply. If aluminum is old: it already has been scuffed by using it but now the cleaning is very important. Dirt will have accumulated in those scratches and will hinder good adhesion of the coating. Clean the floor with a citrus based degreaser and a stiff bristle brush and/or power washer. Rinse thoroughly and dry. Please pay attention to the application temps (min 60F/ max 90F ) . Do not apply in full sun.