This method of sandblasting has a lot of pluses going for it and it does not break up the sand and become airborne which is considered an pollutant and is monitored. Wet sand in the stream of water can hit the object and is recapture in the stream several times before it bounce down or washes off in the stream of water. The only draw back is since metal is so clean it will develop a light rust coat on some metals which is cleaned off with some paint prep.