Patent attributes
The cell wall removal ratio of an elastic foam body is set such that developer or other fouling material adhering to a rotatable member can be continuously absorbed through the cells of the elastic foam body during a single maintenance cycle of an image forming apparatus. For example, the cell wall removal ratio of the elastic foam body is set to at least 60% or at least 80%. When the cell wall removal ratio of the elastic foam body is set to at least 60%, good image quality can be maintained reliably until the number of sheets recorded by the image forming apparatus reaches 20000. Furthermore, when the cell wall removal ratio of the elastic foam body is set to at least 80%, good image quality can be maintained reliably until the number of sheets recorded by the image forming apparatus reaches 30000.