Coatings: Rust Busters

It’s really remarkable what today’s coatings can do – and at minimal risk to the environment.

The marine environment may be the single toughest place on earth for man and machine to operate on a daily basis. We are all familiar with the natural disasters that are spawned by the ocean – tsunamis, hurricanes and typhoons – but the sea itself, the organisms that live inside it, and their allies, the sun and air, treat their man-made visitors with unvarnished [pun intended] hostility.

Protecting vessels from this unwelcoming environment is a host of highly developed marine coatings designed to shield the vessel above and below the waterline. Not only do these products protect, they also serve: Coatings are essential to the efficient operation of a vessel. This essential protection, coupled with the demand for efficiency and an expanding shipbuilding market, means the coatings industry is expected to grow from approximately $5 billion today to over $10 billion in the next three years.

Hull Protection

Hull growth is the number one enemy of a vessel’s speed and efficiency. According to I-Tech Marine Paints R&D Director Lena Lindblad, over 2,000 types of marine organisms latch on to the hulls of vessels, regardless of the construction material, and serve to increase the coefficient of friction and slow the vessel. The end result: Ships require more power to make speed.

With fuel costs the largest component of vessel operation, efficiency is the name of the game. And unlike whales that can scrape barnacles off their bodies by rubbing against a sandy bottom, a ship only has its underwater coatings applied during drydock periods or haul-outs.

For generations the chosen way to slow the growth of marine creatures on a hull was to literally poison the organisms with a toxic coating made of biocides and metals. This method was not only effective at poisoning the organisms but also at poisoning the entire marine ecosystem. Not good.

Current environmental consciousness has completely revolutionized the coatings business when it comes to products applied below the waterline. Due to regulatory and environmental pressures, the world’s coating manufacturers were forced to design very low or zero volatile organic compound (VOC) coatings with minimal amounts of toxins.

With an eye on the private vessel market, Pettit Marine Paint’s Vice President of Sales and Marketing Don Zabransky says that “Green technology has caught up with and surpassed the traditional products in terms of cost and effectiveness.” Zabransky also acknowledges that the increase in the cost of copper from around seventy cents a pound to over $2.50 a pound has made green alternatives financially viable. Pettit’s Hydrocoat line features very low VOC content that beats California’s stringent 300 grams/liter VOC release requirements by a factor of two with only 145-150 g/l. Featuring Janssen PMP’s ECONEA, a copper-free biocide, hulls are kept clear of fouling organisms.

Recently named the hull coating of choice for the world’s largest containerships, Jotun’s SeaQuantum X200 will be applied to the new 19,224-TEU MSC Oscar. The nearly 1,300-foot vessel and its sister ships being built for Mediterranean Shipping Company will feature the ultra-low-friction, self-polishing, 90-month-lifespan coating.

Underwater Coatings

Underwater coatings are constantly evolving, and science is deeply entrenched in the R&D. I-Tech AB’s new biocide Selektope is now being incorporated into Chugoku Marine Paints. According to R&D Director Lindblad, “Most of the antifoulings used in shipping target a broad range of species and therefore feature high amounts of biocides since dosing always has to deal with the most tolerant species. Our approach was instead to target fewer species, enabling lower biocide content.”

Using the biocide medetomidine, known best as a veterinary sedative, I-Tech discovered that by stimulating the barnacle’s swimming behavior it prevented attachment. This promising technology uses a stimulant rather than a toxin to prevent hull growth. Lindblad’s research found that medetomidine was “almost a thousand times more effective than a conventional marine biocide, gram for gram.”

Also entering the market is nanotechnology. Hempel’s new GLOBIC 8000 features a nano acrylate technology binder that makes the product ideal for slower-speed vessels as it claims a fuel savings of up to three percent. For higher-speed vessels, DYNAMIC 8000 features a silylated acrylate technology. Expanding its already extensive product line, Hempel recently acquired protective and waterproofing supplier Jones-Blair.

One of the most comprehensive studies on marine coatings was performed in 2012 by the U.S. Department of the Interior’s Bureau of Reclamation. Testing over 50 coatings and metal alloys in a freshwater system at Colorado’s Parker Dam, the study found that the best method of preventing organic growth were silicone-based, foul-release coatings, which proved effective in both still and moving water. The downside of such coatings is that they are not durable in the face of abrasions or gouging, conditions regularly experienced by vessels that encounter piers, docks, and tugboat impacts.

To combat the durability issue on smaller commercial and recreational vessels, Hullspeed Performance Marine Coatings are incredibly hard and slick, designed for customers who, according to Marketing Manager Ian Germain, “want a durable, eco-friendly coating that can be aggressively cleaned and will not rip when bumped.” Hullspeed customers have seen a fuel-efficiency increase of up to 13 percent and speed increases of up to 10 percent. Unlike traditional bottom paints designed to be reapplied every year or two, Hullspeed is designed for a five-to-seven-year lifespan.

PPG’s fouling-release product SIGMAGUIDE 1290 delivers up to double-digit fuel savings. Its 100 percent silicone binder features a higher density of silicone at the surface to prevent marine organisms from attaching to the hull. To maintain performance over time, SIGMAGUIDE incorporates a dynamic surface regeneration characteristic that allows water to help return the coating to its original state if displaced.

Topside Protection

Any sailboat owner with teak brightwork can attest to the damaging powers of the sun. Topside coatings exist to effectively seal off the vessel from ultraviolet rays, moist marine air and saltwater spray.

NCP Coatings’ DynaSpec product line features military-specified coatings for surface vessels and submarine fleets. DynaSpec coatings are designed to protect interior and exterior aluminum and steel structures, ballast tanks, deck surfaces and high-heat areas up to 1200^o F. They also meet flammability requirements as specified for naval vessels.

For topside use, NCP’s Vice President of Sales and Marketing Glenn Arent says the new SiloxoShield and SiloxoGrip products feature exceptional UV- and chemical-resistance properties. NCP is applying technology to increase environmental friendliness and reduce weight while maintaining corrosion protection. Sold primarily in “haze gray” to the Navy, NCP products are available in other colors for commercial customers demanding the same high-performance coatings designed for surface and subsurface combatants.

Nonskid coatings have been a part of marine vessels ever since holly stone and teak decks were retired under the guise of ease of maintenance. Sand, the usual aggregate for nonskid coatings, has storage and application limitations, so Bipacco Coatings’ owner Tony Brady has created a supremely versatile topside nonskid product featuring a rubber aggregate made from recycled automobile tires.

“Everyone wanted a nonskid that you could roll out,” says Brady. The easy-to-apply, single-coat, non-hazardous coating features 33 percent recycled materials and a three-year stable shelf-life. It has found a home not only on commercial vessels but in many industrial sites and homes. Eco-Tred is equally at home adhering to concrete, steel, aluminum, wood or other painted surfaces and is soft to walk on, unlike traditional nonskid surfaces.

Tank Coatings

As brutal as exposure to the elements is for hull and topside coatings, the coatings lining saltwater ballast tanks have an equally challenging mission. Following several ballast-tank-related casualties, the IMO enacted tough restrictions on such coatings. 

Sherwin-Williams’ Global Marketing Director for Marine, Steve Dickey, says that the company’s Dura-Plate 301 is a purpose-built unique design of epoxy resins and curing agents. According to Dickey, it is the only IMO PSPC (Performance Standards for Protective Coatings)- approved product over UHP (Ultra-High Pressure) on the market today.

Also from Sherwin-Williams is Fast Clad ER, a product designed with the U.S. Navy to meet its stringent requirements for tank coatings and featuring greater edge-retention and a remarkable 24-hour return-to-service time. Most ballast tank coatings typically take a week to cure to an operational state.

Hempel’s HEMPADUR line is also IMO PSPC cargo tank-compliant, and HEMPADUR 15600 is designed as a pure epoxy coating that is resistant to a range of chemicals, including crude oil, up to 176^o F. Also fast-drying, 15600 is surface-dry after only two hours and can be recoated after four hours at 68^o F. A similar new pure epoxy product, HEMPADUR QUATTRO XO, is designed for ballast water tanks but can also be used as a uni-primer for all areas above and below the waterline.

AkzoNobel’s International Paint is applying Interline 9001 tank coating on a series of 18 chemical tankers being built for Navig8 at Hyundai’s Mipo shipyard. Interline 9001 is a bimodal epoxy coating specially designed for chemical tankers with near-zero product absorption and therefore fewer discharge and loading restrictions. Its ability to resist product absorption leads to 70 percent reductions in clean-up costs, allowing faster turnaround time between loadings.

Specialty Products

In addition to the standard coatings, there are specialized products that push the limits of technology and, in the case of Pettit’s Splash Zone Epoxy, suspend a bit of disbelief. 

Pettit Marine’s Splash Zone Epoxy A788, identical to Carboline’s Carboguard A788 for the commercial market, is a two-part patching compound that can be applied to an aluminum, wood, concrete, steel or fiberglass hull. The unbelievable characteristic is that, if your hull is holed, you can apply the epoxy underwater. Once cured, Splash Zone is hard enough to be impact- and abrasion-resistant to the point that it can be drilled and machined if, for some reason, you want to add a fitting to where your hull was holed.

Rust is the enemy of steel vessels, and Pettit’s Rustlok steel primer is designed to be applied to steel, cast iron, galvanized and stainless steel surfaces where, according to Marketing Vice President Zabransky, “it bonds and chemically converts the rust to steel strength.” – MarEx

Todd Vorenkamp writes from New York City.