Various transmission electron microscopy techniques which are useful for the characterization of phase-separation phenomena in glass materials are exemplarily demonstrated at a 40 SiO2-30 Al2O3-18 Na2O-12 LaF3 glass. It is shown that direct imaging of phase-separated regions possesses manifold advantages over the traditional replica technique, particular if the feature size approaches the nano-scale. Although surface replica can be accomplished effortless and made a great leap in glass structure research possible, the method is indirect, i.e. requires a deep understanding of the chemical attack leading to the surface topography eventually imaged. Moreover, surface replicas reach their limits for nanosized features due to the inherent structure of the deposited replica film. © 2009 Elsevier B.V. All rights reserved.