In order to determine the exact influence of filter cloth behavior on the layout of cake forming filters, it is a requirement to carry out laboratory tests in an exact manner. Even if the separation characteristics of solid/liquid mixtures (suspensions) can be described theoretically, the most important parameters of the solid/liquid separation technique must still be determined by carrying out laboratory or field tests. In particular, the influence of the filter cloth on the filtration behavior has to be determined by means of test work with the respective suspension and with an appropriate laboratory test device. A method is described to determine the filter cloth resistance by lab-scale tests under conditions close to reality. The test results are compared to typical characterization cloth data provided by manufacturers.