Abstract: A closed loop method and apparatus is disclosed for spray processing an article such as alodine processing of aluminum. The apparatus includes valved supply and return piping connecting a processing tank with the article therein to a plurality of supply tanks each containing a liquid that is different from the liquid in the other tanks. The valves and two pumps are preferably computer controlled for initiating major steps by circulating liquids from one supply tank at a time through the processing tank for return to the same supply tank. Each major step is followed by an air purging step of at least the return piping for returning sbstantially all flowable liquid into the supply tank from which it originated thereby minimizing contamination of the other liquids. Other apparatus cleans the air of toxic fluids with the environmentally safe air discharged to the atmosphere and the toxic liquids separated into two groups for reuse.