I tape off all the seams and strip the car with paint stripper to bare metal. The results are much better. No heat to dull the body lines. Also you can see every area that has been worked on before. The sanding marks on this car were under the original paint. You would never see this prior work if you sand the car . I only use media on the car where it has surface rust. then I tape the car off and only clean the rusted areas with media.