New Delhi: Researchers have unveiled a new class of anticorrosive pigments based on natural tannins that could challenge traditional, more toxic corrosion-prevention solutions — offering both environmental and performance benefits. The initiative, highlighted yesterday by European Coatings, centres on pigments made from tannin-rich extracts that show strong electrochemical inhibition of steel corrosion.
From plant pods to pigment: how the innovation works
The pigments are derived from hydrolysable tannins — natural polyphenols extracted from vegetable plants (notably the pods of the “Tara” tree) — which are combined with zinc ions to form metallic complexes known as “zinc tannates.”
These zinc-tannate pigments, when used in primers and full paint systems, demonstrated corrosion-inhibiting performance comparable — and in some tests superior — to that of conventional anticorrosive pigments such as zinc chromate or zinc phosphate.
Laboratory tests using electrochemical methods, including direct-current polarization and electrochemical impedance spectroscopy (EIS), confirmed that the tannin-based pigments significantly reduce corrosion current density and increase polarization resistance on mild steel surfaces.
Why the shift to tannin-based pigments matters
For decades, anticorrosive paints have relied heavily on pigments based on heavy metals or phosphates — effective but often environmentally hazardous or subject to tightening regulations.
The new tannin-based pigments offer a “green” alternative — being derived from renewable plant material, non-toxic, and biodegradable.
With comparable protective performance (in inhibiting steel corrosion and preventing rust under aggressive conditions such as chloride or sulfate exposure), these pigments have the potential to reduce the environmental footprint of industrial coatings without compromising on durability.
Implications for coatings, infrastructure and heavy industries
Regulatory compliance & sustainability — As environmental norms tighten globally on the use of hazardous anticorrosive pigments (chromates, heavy-metal compounds), tannin-based pigments could enable paint manufacturers to meet compliance while marketing “eco-friendly” coatings.
Cost & supply-chain benefits — Natural-tannin sources like Tara pods offer a renewable raw-material base, reducing dependence on scarce or heavily regulated inorganic pigments.
Industrial and infrastructure growth potential — Sectors such as marine, offshore, construction, oil & gas, and heavy steel infrastructure — all heavily reliant on corrosion protection — stand to benefit from a more sustainable coating option.
Downstream impact — Use of such pigments in primers and topcoats may lead to safer waste disposal, lower environmental contamination, and improved public perception of companies using green coating solutions.
What’s next — from lab results to commercial adoption
The encouraging laboratory results — showing that zinc-tannate pigments “inhibit satisfactorily steel corrosion” and perform well in full painting systems with alkyd primers — make a compelling case for scaling up.
However, widespread adoption will depend on further real-world testing under varied environmental conditions (e.g., marine atmospheres, industrial pollution, extreme weather), long-term durability studies, cost-efficiency assessments, and adjustments to existing coatings-manufacturing lines.