Abstract: The invention relates to a cleaning system in which, during the cleaning procedure, the articles have to pass a plurality of treatment stations in a direction which is opposite to that in which the flow of the cleaning liquid is established. From the first and most contaminated of the treatment stations, the cleaning liquid is removed and supplied to an ultrafilter. At least part of the outflow from this filter is returned to one of the latest or to the last treatment station. Ultrasonic energy is used to increase the efficiency of at least one of the stations. Ambient heat and vapor loss are recaptured.

Abstract: A solution for chemically polishing surfaces of copper and its alloys contains acid oxalates at a pH value of 3.0 - 5.0 in combination with hydrogen peroxide and one or more stabilizers and brighteners.

Abstract: A method for use in surface treatment systems for maintaining a desired fluid level in the process and rinse tanks. The invention uses a dryrunning-safe pump, inserted in the tank. An overflow for the tank serves as an intake leading to the suction side of this pump. The pressure side of the pump is connected to an outlet outside the tank.