Continuous ink jet printing system for use with hot-melt inks

A continuous ink jet printing system for use with a hot-melt ink, comprising a supply chamber for retaining said ink in a liquid form, means for applying heat to the ink in said chamber to maintain said ink in a liquid form, means for conveying said ink in liquid form from said chamber to a printhead for projection toward a substrate to be marked, catcher means for collecting any of said ink that is not directed to said substrate, means for returning the collected ink as a liquid to the supply chamber, and means for maintaining the ink as a liquid while it is being returned to said supply chamber. Also disclosed is an ink jet nozzle for use in printing hot-melt inks at elevated temperatures comprising an ink jet nozzle body, a transducer, means for acoustically coupling said transducer to said body, and means for maintaining said transducer acoustically coupled to said body at elevated temperatures. Also disclosed is a flexible, heated umbilical tube comprising an inner tube having an inside wall and an outside wall, a heating element that is adjacent the outer wall of the tube, and an insulating layer that surrounds the heating element and thermally insulates it from the environment.