Abstract: In a continuous process wherein corrosion resistant and paint adherent coatings are formed on metallic articles and wherein prior to the formation of said coatings, the articles are first subjected to a pre-cleaning stage in which oil emulsion is removed from the surfaces of the articles by washing the articles with an aqueous solution of wash water and demulsifier and the removed oil emulsion is broken and the oil recovered, and wherein the articles having the oil emulsion removed from their surfaces are thereafter subjected to a second cleaning stage in which the articles are contacted with a cleaning solution to remove metal fines from the surfaces of the articles, the improvement comprising including a chelating agent in said aqueous solution of wash water and demulsifier to aid in breaking said oil emulsion and to deter or prevent the formation of precipitates in the cleaning solution of said second cleaning stage.

Abstract: Oil emulsion is removed from the surfaces of articles by washing the articles with an aqueous solution of wash water and demulsifier, thereby forming a turbulent mixture of the wash water, the demulsifier and the oil emulsion. The demulsifier is effective in breaking the oil emulsion. The liberated oil is allowed to form a separate phase in the solution of wash water/demulsifier, and is removed therefrom in a quiescent stage. The aqueous solution of wash water and demulsifier having the oil removed therefrom is recycled to wash oil emulsion from other of said articles. The preferred demulsifiers are ammonium and alkali metal sulfates and bisulfates.