When a conducting partially-transparent mesh is used to separate two regions of different electrostatic field strength there are short-range changes to the held and potential distributions in the vicinity of the mesh and also long-range changes far from the mesh. The forms and magnitudes of these changes are investigated computationally for meshes that consist of parallel or crossed round wires or crossed flat strips. (C) 1999 Elsevier Science B.V. All rights reserved.