Particles are expected to deposit onto filtering surfaces provided the non-dimensional parameter (see article) U (see article) R2S3/2 exceeds a certain value. For erythrocytes this value has a measured value of 0.15, and for platelets the value ranges from 0.01 to 0.15. If deposition is expected, the rate of particle deposition is proportional to the ultrafiltration flow rate. However, the other fluid mechanic mechanisms may transport a greater number of platelets to the surface. We expect these platelets will be fluid mechanically held to the surface even if it is non-sticky for platelets.