The paper discusses the laws behind the filtering procedures of process liquids through porous materials. At metalwork finishing operations, the use of cutting fluids is of particular importance. During operation, liquids are continuously and intensively contaminated with solid metal parts. To restore the original properties, process fluids are cleaned of mechanical admixtures. The most widely used methods for purifying process liquids are those by filtration.
Derivatives of starch, such as graft copolymer of acrylamide onto starch, carbamoylethylated starch, carbamoylethyl-dihydroxypropylated starch, and dihydroxypropylated starch have been tested for their properties as components of drilling fluids used for clay inhibition and for the regulation of their rheology. The influence of modified starch and their blends with tylose as protective agents in the filtration of drilling fluids, as well as replacement of tylose, by modified starch were investigated.