A drop deflection device suitable for use in a drop marking system employs an electret (9). Electrically conductive marking drops (1) such as inks are given an electrical charge. The drops (1) pass between a pair of deflection plates (8, 9) at least one of which is formed by an electret (a dielectric material which has been subjected to corona discharge to create a relatively permanent electrically charged material body). Depending upon the presence or absence of a charge on a particular drop (1), it will be deflected by the field (6) between the plates (8, 9) on to a substrate (11) for marking. If uncharged, the drops (1) continue to a collection device (10) which returns them to the ink reservoir.