The invention relates to a process for increasing the observed titer of a virus stock for the purpose of increasing the calculated log reduction (LRV) in virus clearance studies. A tissue culture or assay plate is seeded with an indicator cell line and titrated with a virus stock followed, by a centrifugation step for about 5 minutes to about 24 hours at a g-force ranging from about 50×g to about 2400×g, and at a temperature from about 4° C. to about 39° C. The resulting calculated virus titer after undergoing the centrifugation step is 10-fold higher than the virus titer would be if determined in the absence of the centrifuging step.