Freeze fracture describes the technique of breaking a frozen specimen to reveal internal structures. Freeze etching is the sublimation of surface ice under vacuum to reveal details of the fractured face that were originally hidden. A metal/carbon mix enables the sample to be imaged in a SEM (block-face) or TEM (replica). It is used to investigate for instance cell organelles, membranes, layers and emulsions.
Coating of samples is required in the field of electron microscopy to enable or improve the imaging of samples. Creating a conductive layer of metal on the sample inhibits charging, reduces thermal damage and improves the secondary electron signal required for topographic examination in the SEM.