Abstract: A filter has a first filter layer made of TiO.sub.2 of Ti.sub.4 O.sub.7 particles deposited on a second filter layer by stainless steel particles. The first layer has a smaller pore size than the second layer. The construction of the filter, the relative thicknesses of the layers and the resistances thereof to movement therethrough of electrolytically generated gas located between the two layers when the filter is permeated with liquid are such that the gas reaches the upstream side of the filter before the downstream side. In one embodiment stainless steel particles are sintered and rolled with a textured roller before ceramic particles are applied and rolled. An intermediate layer of metal particle peaks and ceramic filled troughs is thus provided which has high tortuosity. The resistance to flow at the metal/ceramic interface can be increased by electrodeposition of metal there.