The invention relates to a means (150) for determining the soiling of a workpiece (108). The means contains a device (155) for capturing dirt particles contained in a characteristic liquid volume on a filter diaphragm (158), said dirt particles being introduced into a liquid when the workpiece (108) is subjected to the action of the liquid. In the means (150) there is a system (169) for analysing the dirt particle load, captured by the filter diaphragm (158), from the liquid. The system (169) for analysing has an analysing means (170) connected to a computer unit (202), wherein the flat filter diaphragm (158) is in the form of a band and can be moved at least sectionally relative to the analysing means (170) by means of a transport device (160). The computer unit (202) connected to the analysing means (170) is used to determine dirt particle measured value (M) in the form of the type and/or number and/or size and/or size distribution of dirt particles (166) accumulated on the section (174) of the filter diaphragm (158).