porous sintered bodies for capacitors formed from valve metals are treated by electrolysis to form a dielectric layer and coated with cathode layers . when standard parallelepiped shapes are used as they were passed , cathode coverage at the sharp corners and edges is non - uniform and failures occur at those locations . treating pressed anode bodies with an abrasive process alters the sharpness of corners and edges , creating rounded transitions between primary surfaces and remove surface imperfections resultant from the pressing process both of which enhance cathode layer uniformity .