Electrospinning is a simple and versatile process for producing small-diameter fibres (nanofibres). However, in spite of the many potential applications of electrospun nanofibres, further process developments are still necessary to achieve a decisive productivity breakthrough for electrospinning plants. Increasing knowledge of multi-jet electrospinning is crucial for developing industrial devices for large-scale nanofibre production. This paper reports on the effect of a non-conducting textile substrate placed between a jet-emitting source (nine-nozzle arrangement) and collector. Shielding the electric field changes the electrospinning conditions, nanofibre morphology, stability of jets and fibre deposition on the collecting surface. Various perturbation phenomena of the electrically driven jets were recorded and are described. The intensity of the perturbations increases as the weight of the non-woven substrate increases resulting in defects in the nanofibrous mat (i.e. beaded nanofibres), production of tick fibres or failure to produce fibrous materials (e. g. films, droplets). The paper also reports an objective image-processing procedure to enhance the evaluation of the collector after nanofibre deposition. (C) 2010 Society of Chemical Industry