Fig. 4From: An analytical survey of zinc white historical and modern artists’ materialsSEM images (secondary electrons, 5 kV, working distance ~ 6 mm) of ZnO powders by Brüggemann (at the top): a indirect method; b direct method; schema of the main ZnO morphologies (at the bottom): c prismoidal shape of hexagonal basis; d acicular shape. The length (L) and width (W) measured on SEM images are also indicatedBack to article page