Mechanisms tannin toxicity

Minium, Pb304, of orange color, is widely used in alkyd paints that serve as primary paints on steel for corrosion protection. In a similar way as chromates and molybdates, minium promotes the passivation of the steel surface, although the reaction mechanisms involved are not all known in detail. Unfortunately, pigments containing lead or chromate are toxic and they will have to be replaced with other compounds that are less harmful to the environment. Molybdates or organic molecules such as the tannins can fulfill this task, but their protective power is still inferior. For certain applications zinc rich paints, provide an interesting alternative. They contain... 

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