Abstract: A method in the processing of aluminum is disclosed, wherein oil from a supply is sprayed onto the aluminum which is processed, whereafter it is collected and passed through a filter and then back to the supply. According to the invention the oil which is used is one which as an additive contains a flocculant selected from the group consisting of dicarboxylic acids having the general formula: HOOC--A--COOH, wherein A is a straight or branched alkylene group of 5-14 carbon atoms or phenylene. The invention also comprises the use of a dicarboxylic acid having the above formula as a flocculant in an oil for the processing of aluminum.