Many of the SEM specimens which we are asked to deal with are highly three-dimensional non-conductive objects, such as silica beads, pollen grains and spores, small inorganic and organic crystals such as zeolites and drug preparations, starch grains, etc. These often cause severe charging problems which result in all of the familiar and tiresome charge-related image artefacts, such as flare, excessive contrast, specimen movement, and variable scan lines. Charging can also make it very difficult to obtain high-resolution images or do satisfactory analysis.