The paper describes how the operational behaviour of cake-forming filters may be influenced through raw gas conditioning and application of further additives. First the basic principles of cake-forming dust separation are described. Then the possibilities of influencing the operational behaviour are discussed, with emphasis on precoating the filter medium and the specific use of additives. The paper then discusses the influence exerted by the gas humidity on dust separation in cake-forming filters, followed by the possibilities of electrostatic and acoustic influences. The complete range of possible influential measures is illustrated by examples taken from laboratory investigations and industrial practice.