Marine adhesive sealants continuously improving

Manufacturers are continuously looking to improve the strength, durability, flexibility and cure times of marine adhesives/sealants.
Examples include 3M Marine’s Fast Cure 4000 UV, ITW Plexus’ MA557 two-part methacrylate, FlexPoxy from Pettit Marine Paints, the West System-brand products from Gougeon Brothers Inc. and Aquabond Marine Repair Compound.
3M’s Fast Cure 4000 UV sealant which was introduced last year, is a non-yellowing sealant that cures within 24 hours to form a firm, pliable, waterproof seal on joints and boat hardware, according to the St. Paul, Minn.-based company.
Fast Cure 4000 UV is a next generation product coming after 3M’s Adhesive/Sealant 5200 “which is legendary,” said Pete Neumann, 3M’s boatbuilding segment marketing supervisor. “It (5200) is 30 years old, it set the benchmark.”
Although 5200 is a “super-strong permanent adhesive/ sealant” it has a five- to seven-day cure time.
Fast Cure 5200, which was introduced about five years ago, has a 24-hour cure time, Neumann added.
Fast Cure 4000 UV was designed for the OEM and the aftermarket, Neumann said. “It’s paintable although it’s best to test for suitability,” he added.
“Boat owners and repair people need to know there is new technology, a new type of product,” Neumann added.
Meanwhile, for OEMs and boat repair yards, MA557 is the newest product from ITW Plexus, said John Norris, spokesman for the Danvers, Mass.-based company.
Plexis MA557 is a two-part methacrylate adhesive designed for bonding large assemblies made from composites, metal and thermoplastics and thermosets including ABS, acrylics, FRP, polyesters (including DCPD modified), PVC, urethanes, styrenics and vinyl esters.
It requires no primers or grinding to apply to gel coats.
Methacrylates first were introduced in the early 1990s and gained acceptance in the boating industry during the mid-1990s, Norris said. “It is a new technology that provides for better, stronger bonding of composite.”
The adhesives became widely used in the recreational vehicle industry during the 1990s because they can bond fiberglass exterior sidewalls to aluminum frames, he added. This is possible because “methacrylates dissolve a microthin layer of each bonding surface that, once cured, creates a chemically cross-linked bond to composites,” according to Pat Shannon, national account manager for ITW Plexus’ Marine Division.
“Traditional assembly methods such as polyester-based marine putties and glass tabbing both require the surfaces to be bonded be prepared prior to assembly,” Shannon said. “Grinding is the preferred method of surface preparation, which creates dust and is labor intensive.”
“While these traditional assembly methods have excellent static strengths, the high modulus or the stiffness of these products do not take the repeated cyclic fatigue cycles as well as a methacrylate adhesive will.
“The combination of strength and flexibility and ease of application makes the use of methacrylate adhesives the preferred choice for stringer assembly,” he said.

Fast Cure 4000 UV
3M Marine Adhesive/Sealant Fast Cure 4000 UV is a cosmetic sealant that cures to form a firm, rubbery, water-tight seal.
“We have conducted extensive testing on Fast Cure 4000 UV to determine its effectiveness below the waterline in harsh marine environments over an extended period of time,” said Trace Woodward, 3M Marine senior technical service engineer. “Results show the sealant is safe for use in fresh and salt water and in temperatures ranging from minus 40 degrees to 190 degrees [Fahrenheit].”
Fast Cure 4000 UV is not sensitive to alcohols, is low odor and is very low in volatile organic compounds (VOCs), making it comfortable to work with and a safe choice for the environment, according to 3M. Tooling can be done with water, making it more convenient than using traditional adhesives or sealants requiring solvents.
Fast Cure 4000 UV has the strength and durability of a mid-strength polyurethane, it has the color-fast properties of a white silicone, and it’s more durable. It’s ideal for sealing holes up in the hull that were made to, for example, replace deck hardware or rub rails or install new electronics.

Plexus MA557
It requires virtually no surface preparation, bonds to gel coats and eliminates time-consuming and costly grinding.
MA557 is for boats larger than 40 feet and offers the stackability needed for larger jobs, according to John Norris, spokesman for ITW Plexus.
It eliminates problems associated with adhesive ‘swim’ [slide] and sag, even when applied to vertical surfaces, said Susan Hennessey, associate marketing manager at ITW Plexus. MA557 will not boil in gaps up to 1.5-inches wide and is available in 490-milliliter cartridges, 5-gallon pails and 50-gallon drums.
MA557 can be dispensed with the standard meter-mix equipment for Plexus purpose-build FusionMate dispensing systems.
By replacing glassed-in wooden stringers with bonded one-piece, all-composite grid systems, Plexus Adhesives have made assembly quicker and easier and have eliminated the problems of wood beneath the water line, Hennessey added.
Plexus adhesives have revolutionized boat building by allowing OEMs to produce stronger, lighter, faster and more durable boats, the company said.

Pettit Marine Paint, Rockaway, N.J., offers its new FlexPoxy high-performance epoxy for repair and construction jobs.
FlexPoxy quickly repairs hulls and topsides made of fiberglass, wood, steel or aluminum. It creates a strong, seamless bond that can be planed, sanded or nailed after full cure, according to the company.
Originally developed for the aircraft industry, FlexPoxy is highly elastic and conforms to the shape and texture of the materials being bonded. It won’t sag, run or shrink, and it can be tinted with oil-based, polyurethane or epoxy paints during application and painted without the need for primer after cure.
FlexPoxy is solvent-free, has no VOCs and can be used at temperatures ranging from 40 degrees to 90 degrees Fahrenheit. The optimum working time is 20 to 25 minutes at 70 degrees Fahrenheit with a full cure in 16 hours.
The FlexPoxy dosing gun dispenses the proper ratio of resin and hardener and the 450-milliliter re-sealable cartridges eliminate waste. It also comes in a 50-milliliter, two-component burst seal package, which allows for easy mixing and application for smaller projects.

West System
Gougeon Brothers Inc. of Bay City, Mich., offers the West System series adhesive and sealant products, including 105 Resin and 205 Hardener for cool weather construction, restoration and repair projects for fiberglass and wooden boats.
West System 105 Resin is a low-viscosity resin that, when mixed with 205 Hardener in a five-to-one ratio, will cure to a solid in six to eight hours and to maximum strength in one to four days.
When using epoxy on aluminum, Gougeon’s West System 860 Aluminum Etch Kit will ensure that a solid, long-lasting epoxy bond is obtained, according to the company. The kit includes the Aluminum Cleaner, an acid conditioner to remove corrosion, and the Conversion Coating that stabilizes the surface to prevent any further oxidation.
For maximum strength for structural bonding applications, boat builders and restorers can use West System 404 High-Density Filler for hardware bonding where high-cyclical loads are anticipated.
The filler is an off-white powder that, when mixed with epoxy, cures to an exceptionally strong plastic says the company. It is designed for use with the West System line of resins, hardeners, fillers and additives for coating, bonding and fairing applications on wood, fiberglass or metal.
For wood projects requiring a tough clearcoating, there’s the West System 207 Special Coating Hardener. When combined with 105 Resin, the mixture forms a strong, moisture-resistant finish that allows the natural color and beauty of the wood to shine through, according to the company.
It is ideal for use on cabin sides, spars, trim, brightwork, wooden decks and stripper canoes. The mixture is formulated to resist clouding and contains an ultraviolet inhibitor to improve resistance to sunlight.
The 105/207 coating cures to a light amber color much like traditional spar varnishes and it also can serve as a base for varnish and improves the durability of the wood’s finish.

Aquabond Marine Repair Compound is a new product manufactured and distributed by Aquabond of California. It is a two-part sandable and paintable epoxy that can be used on any vessel’s surface.
Aquabond allows the owners of fiberglass, aluminum or wooden boats to make repairs above or below the water line. It also makes bolt or cleat repair and installation simple and hassle-free, according to the company.
Aquabond Marine Repair Compound dries white and cures in two to four hours, depending on the temperature.
Aquabond also offers an acrylic for making similar repairs above water. The two-part acrylic may also be used in boat construction and manufacturing and dries quickly.

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