All standard materials used must permit a fine polish and cannot be porous or highly fractured. Such materials will have a continues conducting layer accross the surface and not charge. The original correspondent has charging problems because of the highly porous nature of his specimens. The Canadian supplier was no longer carrying it. The quality is O.K., with some resin areas that charge, but it is essential for looking at edges of material you don't want to carbon coat or heat up.
Most metallurgical companies carry a conductive hot-press material.
Yet another question from the unpredictable world of multi-user facilities. One of our users embeds samples in epoxy and polishes them to eliminate topographical variables. He requires both imaging and EDS, which precludes metal coating for conductivity. He was wondering about the availability of epoxies containing conductive components, which might allow us to use high-vacuum SEM with secondary electron imaging. I'm aware that carbon coating is an option, as well as painting conductive stripes of colloidal carbon or silver to the edge of the embedded materials and down to the aluminum stub.