METHOD FOR WASHING TREATMENT

PURPOSE:To enhance the durability of a detergent and a rinsing liquid and readily wash a metallic part, etc., at a low cost by washing an oily component sticking to a material with a nonhalogen-based detergent composition, rinsing the washed metallic part, etc., then separating a layer of the produced oily component, separating and removing the oily component. CONSTITUTION:This method for washing treatment is to wash an oily component sticking to a material (e.g. a steel plate to which a tempering oil sticks) with a nonhalogen-based detergent composition such as a composition prepared by adding (A) an alkylene oxide adduct expressed by the formula [R and R are each H, a 1-22C alkyl, a 2-22C alkenyl, a 6-10C (substituted)phenyl or sorbitan residue; AO is a 2-3C oxyalkylene; (a) is an integer of 1-20] and (B) one or more hydrocarbons such as a paraffinic hydrocarbon, a condensed polycyclic hydrocarbon or an alkylbenzene to water, as necessary, rinse the surface of the material to be washed, separarte a layer of the oily component produced in washing and/or rinsing, separate and remove the oily component. Thereby, the durability in the detergent and a rinsing liquid is improved to economically and readily carry out the treatment to wash oil foulings from the material.