Extractor-type cleaners are used on cotton stripper harvesters and in seed cotton cleaning systems in the ginning process to remove large foreign material such as burs and sticks. Early research indicated that the shape of the grid bars used in extractors may influence the performance of these machines but studies were not conducted to specifically address this issue. The objective of this work was to evaluate the influence of grid bar cross sectional geometry on extractor performance with regard to foreign matter removal, seed cotton loss, and fiber quality preservation. A laboratory-screening test was used to evaluate nine experimental grid bar geometries along with a conventional round grid bar geometry in twenty-eight machine configurations. Total foreign matter removal and seed cotton loss were influenced by machine configuration. Machine configurations that removed the most total foreign matter also had the highest seed cotton loss. Machine configuration had no effect on HVI fiber quality parameters and a minimal effect on AFIS fiber quality. The results indicate that foreign matter removal and seed cotton loss increase as the open space between grid bars increases. Findings suggest that total foreign matter removal and seed cotton loss can be improved for field cleaners using grid bars with a flat approach and angled relief installed around the bottom saw cylinder.