Cost Identification Practice For a company that produces picture frames, identify each cost as being direct materials, direct labor, manufacturing overhead, or period cost. Wood for frames Interest expense Plant supervisor's salary Company president's salary Wages of assembly line workers Wages of quality control inspectors Depreciation on company cars used by salespeople Research and development Depreciation on plant equipment Advertising Glue for picture frames Box for packaging each completed frame Freight-in on wood Shipping of completed frames to customers Repairs and maintenance of plant equipment Depreciation on office equipment Utilities cost of customer service center 7