The article is focused on the solution of a very urgent problem associated with the diagnostics and prognostication of functional properties of magnetic dactylographic powder. The iron-containing powder is studied. The samples of this powder are obtained using the conductor electric burst. This powder is also investigated using transmission electron microscopy (TEM), X-ray diffraction analysis (XRDA) and hydraulic absorption (pH - measurement). It was shown, that passivation of metallic iron in oxidizing medium forms an oxide film around the iron core. The passivation conditions affect the composition and structure of this oxide film. A new parameter was found, namely, the rate of change of pH aqueous suspension with time characterizing the oxide film adhesiveness. This parameter reflects the hydrophilic / hydrophobic behavior of oxide compounds and can be used for prognostication of functional properties of magnetic dactylographic powder.