A means of clarifying worts and beers by passage through a membrane with pores or convoluted layers of fibres or particles. Solid materials such as trub and yeast are retained leaving the liquid clear. Retention depends on the specification of the membrane which can rapidly block if overloaded. Absolute filtration will remove over 99% of particulate material of a set size whilst depth filtration will be less efficient. Cross flow filtration involves the beer flowing across the membrane and is less likely to block.