A good metal epoxy can repair cracks in the metal hull of a boat, patch a leak in an oil pan, or fix leaky metal plumbing in an older home, making it an essential item for repairing aluminum and other types of metal. Epoxy consists of an adhesive and a hardener that must be mixed just prior to use. Once combined, epoxy creates a tight bond between metal pieces that can withstand forces of up to 3,000 pounds per square inch (psi) and temperatures of more than 500 degrees Fahrenneit. Many epoxies are also water resistant. The best epoxy for aluminum will also work well with other metals, making it ideal for repairing boats, RVs, automobiles, and even household plumbing.
This guide will examine the critical factors to consider when shopping for the best epoxy for aluminum repairs while identifying some of the top products on the market.
- BEST OVERALL: J-B Weld 8271 KwikWeld Steel Reinforced Epoxy
- BEST BANG FOR THE BUCK: Loctite Liquid Professional Super Glue
- BEST FOR HOUSEHOLD: Gorilla 2 Part Epoxy
- BEST FOR WATERPROOF: J-B Weld 8277 WaterWeld Epoxy Putty Stick
- BEST HEAVY-DUTY: Hy-Poxy H-450 Alumbond Putty Aluminum Repair Kit
- BEST VERSATILE: PC Products PC-7 Epoxy Adhesive Paste
- BEST FOR BOATS: Amazing GOOP 5400060 Coat-It Epoxy Sealer Adhesive
What to Consider When Choosing the Best Epoxy for Aluminum
While most people focus on strength when choosing an epoxy glue, many other factors are also essential to consider, including intended use, water resistance, temperature tolerance, and drying time. Ahead, learn more about these and other characteristics of this powerful adhesive.
Epoxy that can repair aluminum and other metals comes in various forms ranging from liquid to putty. The type of repair largely dictates the kind of epoxy one should use. Liquid epoxy in small 1-ounce bottles with syringe-style applicators is suitable for smaller applications around the house. For larger applications, such as repairing a boat hull, use a liquid sealer epoxy that can be applied with a brush over a broad area. Repairing metal pipes, valves, and ductwork requires a putty epoxy that will mold around the fittings.
Epoxy with a high temperature tolerance is suitable for automotive repairs, such as sealing cracks in an oil pan or gas tank. For boats and plumbing, choose a waterproof epoxy. The orientation of the repair can also determine which is best. A vertical repair or one located overhead may be better suited for a putty that will stick in place as opposed to a liquid epoxy that may drip or run off of the repair before it has a chance to set.
While many aluminum epoxies are nontoxic, containing no chemicals that will harm the environment or pose a significant health threat, they can still create health hazards. It’s wise to check the product’s label to determine how to use the epoxy safely. Some epoxies can cause skin irritation or release harmful vapors. When using epoxy, make sure to use gloves and goggles to protect the skin and eyes, and work in a well-ventilated space.
It’s also essential to take the proper safety precautions when storing and using the material. Store the epoxy in a temperature-controlled room that stays around 70 degrees Fahrenheit in a cabinet or storage closet not accessible to pets or children.
Epoxy glue is only as good as its ability to hold two materials together, plug a hole, or seal a crack without failing. An epoxy’s tensile strength, measured in pounds per square inch (psi), indicates the maximum opposite direction load the epoxy can endure before it pulls apart. Most manufacturers list this number on the packaging. Many epoxies have a tensile strength of around 1,000 psi, which is suitable for most applications. The strongest epoxies have a tensile strength of 3,000 psi or more, which is ideal for applications in which the materials will be under a significant amount of stress, such as on a vehicle or boat.
Epoxy compatible with aluminum and other metals must be able to endure scorching hot temperatures for certain applications. Most epoxies have maximum temperature ratings ranging from 200 degrees Fahrenheit to more than 500 degrees Fahrenheit.
Epoxies also require certain temperatures to set and dry properly. Pay attention to the temperature range for application, which is typically in the product instructions. Many require the temperature to be above 40 degrees Fahrenheit for the epoxy to set and cure properly. Most epoxy manufacturers list temperature requirements for application on the packaging and the maximum temperature the epoxy can endure once fully cured.
Automotive and boat repairs, as well as plumbing fixes, must be able to hold up to the elements. For these applications, look for waterproof epoxies designed for use in areas exposed to rain. Most liquid epoxy must be applied to a dry surface but is waterproof once it fully cures. Waterproof putty epoxies are suitable for repairs to wet surfaces, such as a plumbing fixture. Some will even set and cure underwater, making them ideal for repairs to a boat hull.
Some epoxies are more versatile than others. It’s essential to look at what types of surfaces they are compatible with and whether they’ll work with the desired application. Some, but not all epoxies, can be sanded, molded, painted, or drilled.
Other epoxies will work on more than just metal. Most epoxies are also compatible with wood, tile, concrete, plastic, PVC, and even glass. A versatile epoxy isn’t just helpful in repairing aluminum; it’s also handy for having on hand in the garage or shed for quick repairs around the house.
Finish and Drying Time
Drying time can be an important factor to consider when purchasing an epoxy, especially for outdoor repairs. Most epoxies have a set time and a cure time. The set time is how long it takes for the epoxy to hold its bond without a significant amount of force being applied to it. The cure time is the amount of time it takes for the epoxy’s bond to reach full strength.
Dry times for epoxies can vary from a few seconds to a few hours. Dry time can impact the type of repairs that the epoxy is suitable for. While a set time of a few hours may be fine for an epoxy used to seal a hole or repair two metal pieces clamped together, it won’t do for a repair held together by hand.
Epoxies also dry to different finishes. Common finish colors include white, gray, and transparent. If the joint is visible, consider which color will produce a more aesthetically pleasing result when choosing epoxy or check to see if the epoxy is paintable.
Epoxy comes in two separate tubes or containers: resin and hardener. True to its name, the epoxy resin will not harden and set until it mixes with the hardener. Epoxy application entails mixing one part of each on scrap material or a tray then applying it to the repair. Once the epoxy is mixed, it’s crucial to use it right away to achieve the best results.
Application varies depending on the type of epoxy. Liquid epoxy is typically applied using a craft stick. To apply putty epoxy, knead it together, then shape it around the repair by hand. Larger epoxies designed to seal broad surfaces, such as a boat haul, can be applied using a wide paintbrush.
Our Top Picks
The list below includes some of the best epoxies for aluminum and metal repairs—everything from general household repairs to fixing cracks in boat hulls. It includes epoxies with high tensile strength, quick dry times, and water-resistant properties. Any of the epoxies below make a good choice for use on aluminum.
When it comes to gluing metal together, strength is crucial to a successful bond, which is why this two-part epoxy from J-B Weld is so good. Once fully cured, it boasts a tensile strength of 5,020 psi and can withstand temperatures of up to 550 degrees Fahrenheit. That makes it ideal for applications ranging from automotive to boat to household needs.
What’s more, this product can be drilled, molded, sanded, and painted without compromising its strength, making it one of the more versatile epoxies on the market. It’s also usable with PVC, wood, concrete, and ceramic tile. The application involves creating a 1:1 mix from both tubes, applying to the joint, and waiting 4 to 6 hours for the glue to set and a day or so for it to cure fully. J-B Weld KwikWeld, which dries to an opaque gray color, comes in two 5-ounce tubes.
A low price coupled with a simple one-step application makes this super glue a great budget option to have on hand around the house for miscellaneous repairs. Though technically not an epoxy—it’s a cyanoacrylate—it can handle many of the same duties. It requires no mixing and sets in just 15 to 30 seconds, making it ideal for gluing together metal pieces that need to be held together by hand until the glue has set.
An extended nozzle on the 0.7-ounce bottle makes it easy to control the amount of glue that comes out, preventing drips and mess. Loctite dries clear, creating an invisible bond. In addition to metal, Loctite is also compatible with ceramic, rigid plastics, rubber, wood, ceramic, and even leather. Strength once fully cured for 24 hours is a sturdy 2,900 psi.
It’s the simple yet innovative application design of this two-part epoxy from Gorilla that makes it such a great option. While other two-part epoxies put their resin and hardener in two separate bottles, Gorilla uses an ingenious syringe design with two separate compartments for resin and hardener. When the user depresses the syringe to apply, the two are released in equal parts, eliminating the need to juggle two separate bottles.
It also sets in just 5 minutes and cures in 30 minutes, making it an ideal solution for household repairs. With a psi rating of 3,300, Gorilla Epoxy is an excellent epoxy to have on hand to make lighter-duty household repairs in a pinch. Gorilla 2 Part Epoxy comes in a 0.85-ounce syringe.
Aluminum repairs on boats or even in household plumbing must be able to withstand water. This waterproof epoxy isn’t just waterproof—it will set and cure underwater. It comes in two putty sticks: one for the resin and one for the hardener. Application requires the user to knead the two together, then apply. Whether underwater or above water, it sets in just 25 minutes and cures in about an hour.
Its unique waterproof ability makes it ideal for boat and plumbing repairs, especially in places where air-drying the repair project isn’t an option. WaterWeld has a 1,300-psi shear strength and can withstand temperatures up to 350 degrees Fahrenheit. In addition to metal, WaterWeld is also compatible with fiberglass and plastic, making it an excellent all-around repair adhesive for boats.
While this product’s excellent tensile strength of 3,500 psi makes it ideal for larger aluminum repair jobs, it’s also one of the few epoxies out there specifically designed to work with aluminum. What makes it different from other epoxies is the tiny bits of aluminum in the mix that give it tremendous adhesion ability with aluminum. This formula’s putty consistency makes it ideal for auto repair and for fixing HVAC pipes, valves, radiators, and the like.
Other benefits of this epoxy include its ability to cure in just 45 minutes. It’s also sandable and drillable. Hy-Poxy, which comes in two 6.5-ounce tubes, dries to a gray color that matches nicely with aluminum and is also paintable. To apply, knead the two putties together.
With its ability to function as an adhesive, filler, or bonding agent, this product from PC Products is one of the more versatile epoxies on the market. These characteristics make it ideal for filling holes and repairing cracks, making it a good option for fixing a leak in a water tank or sealing off a leak in a gas tank or oil pan. Adding to its versatility is its ability to work with a wide variety of materials, including fiberglass, wood concrete, brick, and ceramic, as well as metal.
Its tacky consistency also makes it a good choice for working on vertical or overhead spots. Just bear in mind that its temperature tolerance is lower than other epoxies at 200 degrees Fahrenheit. Epoxy Adhesive Paste comes in two cans for the resin and hardener, requiring the user to mix the two pastes for application.
Sealing cracks and minor leaks on the hull of a boat or protecting the surface from future damage requires a product that can cover a lot of surface area. This product from Amazing GOOP goes on easily and provides broad coverage, making it ideal for more extensive repairs. Once it’s mixed, the user can apply the epoxy with a wide paintbrush, making quick work of a boat hull repair project.
The epoxy sets and dries in 10 hours, enough time for the user to apply it and quick enough to get the boat back on the water with little delay. With Kevlar fibers in its composition, once cured, this product creates a thick barrier that not only seals small cracks but also protects the hull from future damage. Amazing GOOP waterproof epoxy, which dries to a black graphite finish, will bond to aluminum, steel, fiberglass, and wood, making it ideal for various types of boats.
FAQs About Epoxy for Aluminum Repairs
If you have questions about using your epoxy on aluminum, read on for answers to some of the most common queries about this adhesive.
Q. Can epoxy be used on multiple surfaces?
You can use most epoxies on various surfaces, including wood, metal, plastic, concrete, and tile.
Q. Do I need to prime the aluminum epoxy before painting?
It’s a good idea to prime aluminum and aluminum epoxy before painting it. Use a self-etching primer, which will create a tight bond to the metal.
Q. How do you prepare aluminum for epoxy?
Clean the aluminum thoroughly, making sure it’s free of rust, dirt, paint, and oil before applying the epoxy, then lightly scuff it with sandpaper or a metal file so it adheres better.
Q. How do you apply epoxy resin?
To apply the epoxy resin, put equal parts of the resin and hardener onto a disposable surface, then mix. Depending on the type of epoxy, this can involve mixing with a tool or, in the case of putty, kneading with fingers. Apply the mixed epoxy to the surface as needed to join or repair.