on the high seas
Because anti-fouling protection makes shipping more efficient and sustainable, fleet operators and ship builders are looking for effective protective paints. Evonik is making today’s paint recipes especially effective and is also working on the coatings of tomorrow.
Measuring 400 meters in length and boasting more than 80,000 hp, the largest container ships that currently ply the world’s oceans often have up to 19,000 containers on board, representing almost 200,000 tons of freight. However, a tenacious enemy of these giants of the seas is microscopically small.
In a process called fouling, these tiny microorganisms and algae create a slimy organic film on all ships’ hulls that are in the water long enough, no matter whether the vessel is a luxury yacht or a deep-sea freighter. Once this “soft growth” has made itself at home on the hull, it is followed somewhat later by mussels, barnacles, and other types of “hard growth.” These “stowaways” not only increase the ship’s weight but also promote the corrosion of the hull, thus necessitating frequent maintenance work in dry docks. Fouling particularly increases flow resistance, because only clean and smooth hulls glide optimally through the water.
Head of the Paints & Coatings Industry Team
This has a huge impact on the energy efficiency of shipping and thus on its costs and carbon footprint. That’s because a strongly fouled container ship can consume up to 40 percent more fuel than a clean one. With consumption figures measured in hundreds of tons of bunker oil per day, this is a considerable amount, and it is also the main reason why fleet operators and ship builders use effective anti-fouling products. These products consist of ship paint that keeps fouling at bay for as long as possible.
The ancient Romans were already familiar with the most important anti-fouling agents against marine pests: metals such as lead and copper that prevent the organisms from attaching themselves to the hull. That’s why the paints used on ships today contain copper compounds. The typically red color that adorns the hulls of merchant ships is caused by copper oxide in the paint. By contrast, the paints used for recreational craft mostly contain copper thiocyanate, which is white but much more expensive than copper oxide.
Every large merchant ship is painted with hundreds of tons of coating to protect it against the elements and corrosive cargo. Almost all of the coatings—whether for the deck or the ballast water tanks—contain products from Evonik, which improve the coatings’ resistance to the rough conditions aboard a ship. In addition, Evonik products in the formulations of the anti-fouling paints ensure that extremely tiny layers continuously peel off to uncover new copper underneath. This keeps hulls clean longer so that fewer stays are needed in dry dock. It also ensures that the same effect is achieved with less copper, which is beneficial from both an environmental and an economic point of view.
Moreover, Evonik works together with paint manufacturers and research institutes to create new formulations and new anti-fouling systems. The aim is to create paints that are especially effective and sustainable. For example, paints might not need any copper in the future, as they will create surfaces that mechanically prevent organisms from attaching themselves to the hull in a kind of lotus effect for the giants of the seas. The tiny stowaways would then no longer pose any threat to the leviathans of the high seas.
Specialty products from Evonik are also helping against undesirable adhesiveness of a different kind: graffiti. A special surface coating protects facades against spray attacks, repelling spray paint and markers so they can be easily removed. Although subject to the full force of the weather and repeated cleaning, the coating lasts for several years.