Discussion of the results of the thin foil method applied in studies of metal objects obtained from archaeological investigations. Electronic microscopic exposure was used in examining iron slabs, being semi-finished products of minor degree of working, shield bose and nails from the Roman period which are highly processed. The actual aim of the investigation was to observe the probable structure of effects associated with prolonged low-temperature aging and possible establishment of the technical conditions of their production. In addition the chronology of the finds was verified. -- AATA