An experimental study has been undertaken in which the loading behaviour of an electrically active fibrous filter material has been investigated. In these experiments both filter pressure drop and penetration have been monitored continuously while samples of filter material have been loaded with monodisperse stearic acid particles. This paper concerns itself only with the pressure drop data. The experimental findings suggest that electrically active materials should have greater dust holding capacities than conventional materials, and a mechanistic explanation as to why this should be is presented. This mechanistic explanation is supported by two-dimensional simulations of dendrite formation.