Perforated sheets in solvent extractors are used to facilitate the efficient flow of solvents and materials through the system. These sheets are made from metal, such as stainless steel, and feature a pattern of holes that allow for selective passage of particles while retaining larger impurities. The perforations help in evenly distributing the solvent and ensuring effective extraction by providing consistent contact between the solvent and the material. Their design also aids in preventing clogging and maintaining optimal flow rates, thus enhancing the overall efficiency and performance of the extraction process.