I have a friend who is working on a 49 ford project,he sent the entire body,in pieces down to L.A. , minus the frame.The media that was used was walnut shells,I saw the car before and after and all i can say is what difference.The rusted spots exist no more and you have clean bare metal,well worth the 800 bucks he said it cost.It looked to me like all rust gone and 99.2 percent of the paint in the crevices.