Anti-fouling Coating Research by Jules Dock

Jules Dock is a young enterprise that, among other things, conducts research into sustainable maritime practices in different promising fields. Pieter Welling, research coordinator at Jules Dock, currently works with his team on a project that focuses on anti- and biofouling. The project is funded by the European Fund for Regional Development. Jules Dock obtained this grant in collaboration with the Mobile Heritage Centre (in Dutch: Mobiel Erfgoed Centrum or MEC).

In the current economic environment, where financial performance and corporate social responsibility go hand in hand, there is a growing demand for sustainable means of anti-fouling (from here on called coatings). This is supported by legislation which, for instance, has banned the use of tributyltin (TBT) in coatings due to its harmful effect on the environment. TBT is a biocide, which slowly dissolves from the coating and creates a toxic environment around the coated surface, preventing marine growth. Recently, biocide coatings have been developed that make use of other substances, such as copper and/or organic compounds. Also fouling release coatings have been up and coming, these coatings do not use biocides. The fouling release coatings create a slippery surface, often through the use of Fluor and/or Silicon-polymers, to prevent biofouling from attaching. These coatings have the added advantage of not releasing the often toxic biocides into the environment. The newest coating developments use the up and coming field of nanotechnology.

To assess the sustainability of coatings, among other things the performance of these coatings needs to be evaluated objectively.

Available researches into the performance of coatings do not use objective parameters.
Often the performance of coatings is judged just by looking at the coated surface. Terms like “This coating performs well” are often observed but one can hardly call that objective.

At Jules Dock we have set up a research method which uses objective parameters as assessment criteria, this research is carried out at the moment of writing. The method uses steel discs that were firstly coated with an anti-corrosion paint, which will protect the discs from the corrosive effect of the environment. 5/6 of the discs have then been coated with five different coatings. The other 1/6 have also been submerged, but have not been treated with an additional coating. They will serve as reference, giving a better sense of the performance of the coatings. Before the discs were submerged in water they were weighed. The discs are light enough that they can be weighed on an analytical scale. These scales can weigh with an accuracy of up to 0,1 mg and thus can measure the weight increase, due to bio-fouling growth, accurately. Subsequently, the discs have been submerged in the Biesbosch (fresh water), the harbor of Rotterdam (brackish water) and the Oosterschelde (salt water).

When the discs will be retrieved in the beginning of October, they will be dried and weighed. Comparing the final dry weight to the initial weight, from before the slides had been submerged, we can get an accurate sense of how much biofouling has accumulated on each disc. After the discs have been weighed, a Calcium determination via Atomic Absorption Spectroscopy (AAS) will analyze the amount of Calcium in the biofouling. Hard organisms will most likely result in a bigger increase in friction than soft organisms. Hard organisms contain more Calcium and so the financial and sustainable performance of a coating could also be dependent on the amount of Calcium in the biofouling. These analyses will be performed by biology- and Chemistry students of the Rotterdam University of Applied Sciences (in Dutch: Hogeschool Rotterdam).

In the future Jules Dock wants to use this method of research in the development of a bio-based coating of which the anti-fouling and sustainable performance rivals or exceeds that of existing coatings. Jules Dock also strives to use this research method in finding the optimum coating for the sustainable vessels currently in development.

Would you like to know more about our research towards anti- and biofouling? Please contact Pieter Welling, Coordinator Coating Project, p.welling@julesdock.nl

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