This paper investigated the possibility of forming a modified rust layer by combining various natural, non-toxic corrosion inhibitors with chestnut tannin as the basic inhibitor. Other investigated inhibitors were starch, polyethylene glycol (PEG 400), propolis and hexamine. The visual inspection of the formed layers was selected as the initial evaluation parameter in order to obtain an optimum concentration, as well as the type of inhibitor: 300 mg dm^-3 tannin concentration (T300) in synergism with the 80 mg dm^-3 propolis concertation (P80) creates a layer with the best appearance. The quality of the optimized layer was further confirmed with SEM and FTIR analysis, suggesting the modification of the rust layer by formation of iron tannate. More detailed insight into inhibitory properties was obtained by electrochemical methods in 3.5% NaCl solutions. The results obtained by electrochemical impedance spectroscopy (EIS) somewhat favor the use of the combination P80 + T300, but the final confirmation of the protective properties is definitely given in the polarization curves. Increasing mixing rate during measurements of the P80 + T300 leads to a negative shift of the corrosion potential, indicating the cathodic behavior of the protective layer as an oxygen diffusion barrier of high electrolyte resistance. Maximum inhibition efficiency was obtained at 1000 r min^-1 and equals 73.71% with respect to the rust layer and 73.35% with respect to the pure carbon steel. Thus, the potential application of the protective layer properties was found to be in systems of flowing aerated water or salt water.