I have a job to do. Some steel frames (the "legs" of a heavy wooden table and two benches) have to be sandblasted. I tried several steelworkshops in Chiang Mai but they do not know about it. If you not know: "sandblasting is a technic to clean the surface of metal by blowing air with fine sand particles over is. More or less like using "sandpaper", but it is easier to do and the result is a much nicer texture of the surface.