the invention relates to a filter fabric , particularly of single - strand metal - or plastics filaments , in which one system of the two intersecting systems of filaments consists of filaments of thicker , mutually equidistantly spaced filaments extending in a straight line and the other system of thinner , sinusoidal filaments which are mutually juxtaposed as closely as possible and which embrace the thicker filaments and in which the filter gauge is determined by the diameter μ of the largest measuring sphere which passes through the apertures in the triangular pores of the fabric which are each formed by a thicker filament and two adjacent , phase - displaced , thinner filaments . the expression &# 34 ; filaments &# 34 ; embraces metal wires as well as plastics filaments .