Application of natural materials in marine paint formulations

Trials to develop environmentally friendly marine paints based on natural materials as replacement for copper and tin compounds for fouling and marine corrosion control.

Green algae, tubeworms in dead powder form and garlic were used as natural anti‐fouling components in the paints developed. Electrochemical technique was employed for testing the potential of both tubeworms and garlic in terms of inhibition of steel corrosion in seawater. Marine paint formulations containing each of the three selected natural materials were applied onto PVC and un‐primed steel surface, which were immersed in natural seawater for the assessment of their anti‐fouling and anti‐corrosion properties. The results of visual assessment and seawater analysis were also used for such an evaluation.

Tubeworms act as mixed type inhibitor while garlic affects the potential cathodic process of steel in seawater. Tubeworms‐based paint, with 25 per cent in the dry paint film, could protect steel surface from marine corrosion up to 7 months. The paints containing algae and garlic, and the corresponding algae/garlic free paints, resisted slime film formation. Steel and PVC coated surfaces with paint containing algae showed the best anti‐fouling potential within the prepared series.

The investigation only involved the application of the dead form of green algae and tubeworms as effective pigments in the developed paints. It is recommended that further research should focus on extracting and identifying the active components in each organism against fouling and marine corrosion.

The paint formulations developed (containing 25 per cent by weight tubeworms in the paint film) could be used to protect un‐primed steel surface against fouling and marine corrosion for a reasonably long duration.

The application of one paint formulation on un‐primed steel surface for its protection from both fouling and marine corrosion is novel. The electrochemical studies of steel in natural seawater in presence of tubeworms and garlic are original.