firms in process industries mass produce large quantities of similar or homogeneous products. examples of process manufacturers include food, cement, petroleum, and chemical firms. one gallon of paint is the same as another gallon. the important point is that the cost of one unit of a product is identical to the cost of another. service firms can also use a process-costing approach. for example, check-clearing departments of banks incur a uniform cost to clear a check, no matter the size of the check or the name of the payee.