Abstract: A device and method are set forth for continuous, fumeless treating of products like steel wire. The device includes a generally closed tank having an inlet opening to pass the wire through a passageway to exit the tank at an outlet opening. Intermediate the inlet and outlet openings along the passageway are means for treating the wire in the desired manner. To prevent fumes from the treating means from escaping through the inlet and outlet openings, the tank is provided with means for continuously cascading a liquid across the openings to define barriers against the escape of such fumes while still permitting the product to be drawn through the tank. Preferably the tank has a removable top. Extending along the sides of the top are downwardly depending side skirts which are received by and are partially submerged in the liquid filled troughs to seal against the escape of fumes.