Inside the trunk, moisture had accumulated between the trunk mat and trunk floor, which rusted the area. Because the walnut-shell media will not remove rust, AFCO hit the area with StarBlast to remove both the paint and the small amount of surface rust. StarBlast knocks the scale off without harming the metal. Some media-blasting shops use StarBlast on the entire car body (inside and out) with great results. Again, it depends on the particular car's needs.