The aim of this research was to evaluate the anticorrosive properties of alkyd paints and wash primers formulated with zinc tannates containing Tara tannins. Their inhibitory efficiency was compared with paints pigmented with well-known anticorrosive pigments by accelerated corrosion tests (salt spray test, Prohesion test, and sulphur dioxide test), natural exposure tests and some electrochemical techniques (corrosion potential, polarization resistance and impedance measurements). It was demonstrated that the capacity of inhibiting corrosion of zinc tannates is equivalent to that shown by most commercially available conventional pigments, such as zinc phosphate and zinc chromate.

Hydrolysable tannins are natural polyphenols susceptible to hydrolysis that can be extracted from different vegetable plants. Tara pods, of Peruvian origin, concentrate a high tannin content and, besides their low exploitation impact, their tannin extract has shown high potential industrial applications due to their ability to form complexes with a broad variety of metal ions. However, developing an anticorrosive pigment of low-cost, high efficiency and reduced environmental impact is still a challenge. Herein, tannin-rich pigments were synthesized with Tara powder and zinc ions to produce metallic complexes known as tannates for corrosion protection. The anticorrosive behavior of zinc tannates was studied by direct current electrochemical techniques on pigment extracts and electrochemical impedance spectroscopy tests by analyzing pigmented primers and painting systems. Scanning electron...