It has been shown in electrorheology that filtration occurs and that it impacts the structuring and rheology of electrorheological fluids under an electric field. This paper demonstrates the impact of filtration on the mechanical properties of these systems in compression. By varying the Pe number, it was shown that the Pe number was an effective indicator for electrorheological fluids in squeeze flow under an electric field. Finally, the study demonstrated the gradual transition from a close packed limit in compression, where filtration was significant, to a homogenous limit where filtration effects were low. This paper then proposes a comprehensive qualitative description of electrorheological squeeze flow discussing the impact filtration has on electrorheology. (C) 2010 The Society of Rheology. [DOI: 10.1122/1.3378762]