AbstractA method for estimating the averaged specific resistance of filtration cake, which avoids the necessity of measuring the liquid invasion volume in capillary suction apparatus (CSA) experiments, is proposed. When insufficient slurry is used, the slurry will exhaust during an experiment and the curve of wet front radius versus time shows transition. The transition point shifts according to the slurry concentration, cake specific resistance and the CSA parameters. Based on the wet front radius and the capillary suction time (CST) of the transition point, the liquid saturation under the inner cylinder can be estimated and the averaged specific resistance of cake calculated without the liquid invasion volume data. The proposed method agrees well with vacuum filtration data.