When it comes to gluing metals, you have to be careful. There are a large number of commercially available glues that simply won’t bond with metals such as aluminum and steel. Labeling will often tell you which glues will bond to aluminum, but this is not universally true.
This is why I thought that some research was necessary. Since epoxies are usually the strongest class of glue, I have put together a list of the top 5 epoxies that can be used on aluminum. Extensive research has been done to ensure that all of these products are safe and effective for use on aluminum surfaces.
|Product||Cure time (hours)||Color|
|1|| 3M Marine Adhesive/Sealant 5200 |
|48||white, black, tan, mahogany|
|2||Loctite Liquid Professional Super Glue||12-24||clear|
|3||PC-7 Epoxy Paste||48||grey|
|4||J-B Weld KwikWeld Quick Setting Steel Reinforced Epoxy||4-6||grey|
This kind of adhesive is commonly used for boats, kayaks, jet-skis, and other marine vehicles. This product has a proven history of effectiveness, though it is not without its downsides. It takes a long time to dry, and even longer to cure.
This particular version is meant to bond very quickly, fixing the object in place within seconds. Loc-tite is so strong that you have to be very careful with it, which represents its first significant drawback.
It bonds well with virtually everything including aluminum. That being said, Loctite’s Professional Super Glue is a bit on the expensive side.
For one, it can be applied as either a filler aluminum patch or a coating with equal efficiency. For another, it can bond to virtually any surface except for certain plastics. It should bond very easily with aluminum.
The product comes in a tube that contains two different substances that are mixed together to create a long-lasting and paintable filler. It requires only one day to cure and gives the user 30 minutes to an hour of work time before the mixture begins to harden.
The only real disadvantage to this product is the fact that it has to be used within 30 minutes of mixing to avoid waste. This product does create an ugly surface, but the fact that it can be painted makes this less of a problem.
If you know anything about epoxies, you probably know what J-B weld is. It contains powdered steel, making it an exceptionally strong glue. It also allows the glue to bond more easily with a metal surface, including aluminum.
J-B weld is perfect for applications that require a high-temperature epoxy, as it can withstand temperatures of up to 300 degrees Fahrenheit.
There are those who claim that J-B Weld is not as strong as advertised. However, when we look at their stories we can see a pattern. It seems that some people expect J-B Weld to be as strong as solid steel.
The KwikWeld variety is meant to be a faster-drying version of the classic formula. One small problem is that JB Weld doesn’t adhere to a surface quite as well as some of other choices on the list.
This is the only product on the list that is specifically intended to bond with aluminum. At first glace, this alone might make it seem like the best choice. When you look at reviews for the product, most of them are positive.
Some users did report a failure to bond with certain aluminum surfaces, particularly when doing automotive repairs. This could be due to the dirty nature of automobile parts in general.
A dirty surface would impair the adhesion, to be fair. The only provable negative that I can find with this product is its somewhat ridiculous price.
When selecting an epoxy for your next project, you should be aware that there is no one answer for everything. An epoxy that works great for one purpose may not necessarily work so well for another purpose. There is no one-shot cure-all for everything.
However, the above doesn’t really help you very much when it comes to specific options, so let’s take a look at the factors you need to consider.
Usually, this won’t be a big factor. When a problem needs to be fixed, it doesn’t really matter if it takes a little longer. That being said, professionals who are working on a timeframe might find this factor to be a lot more important. As a professional, you want to get the job done quickly so that you can get paid and move on to the next job. For the home user or the hobbyist, it simply boils down to convenience.
Most types of glue will tell you their exact tensile strength in pounds per square inch somewhere on the package. You may have to look for it, but it is most likely there. This gives you a set of numbers that you can compare when deciding which glue will be sufficient for your needs.
Ask yourself what kind of temperatures your surface will be exposed to. Think about the hottest temperature that it will ever see. In most cases, you don’t need to give a whole lot of thought to this, but when fixing anything that comes into contact with high temperatures, it will be a critical factor.
Looks and Paintability
Not all epoxies can be painted. While this may not matter for strictly utilitarian jobs, cosmetic issues may be relevant for the average home user fixing a piece of furniture. It doesn’t do much good to fix your things if they turn into an ugly mess in the process. Make sure you always check the packaging to see if your epoxy can be painted.
Frequently Asked Questions
Will epoxy glue stick to aluminum?
Yes, epoxy glues will stick to nearly anything. That being said, there is an extra step that must be taken if you want your aluminum-epoxy bond to hold strong. Aluminum doesn’t exist in nature (at least not in an unmixed form) and comes instead from an ore called Bauxite.
When made pure, aluminum tends to react with the atmosphere readily. This results in a dull gray layer of aluminum oxide developing on the surface. Unlike iron oxide, aluminum oxide isn’t corrosive, so you don’t need to worry much about that. However, that oxide layer can prevent the epoxy from bonding to aluminum surfaces properly. All you need to do is clean the bonding surfaces with something abrasive, and you should have no problems.
How do you bond aluminum without welding?
Because aluminum melts rather easily, you don’t really need a welder to achieve proper bonding. You can always use mechanical methods like screws and rivets, but that doesn’t really create a “bond.” You can also use epoxy as described in the last question, but the oxide layer can make that problematic.
A lot of people will use soldering as an alternative to welding. In fact, it is a much better alternative for soft metals. An acetylene torch (which is needed to melt steel) is so hot that it would destroy aluminum quickly. It takes at least 2500 degrees Fahrenheit to melt steel, while aluminum requires only about 1200 degrees.
Soldering involves the use of rods that are made of similar metals. An inexpensive propane torch is used to melt the rod, allowing the metal to flow into the desired cavity. This does take a little bit of skill, but it’s a pretty basic process.
It probably surprises you that a tube of glue can be this complicated. However, most of the products that we use on a daily basis have complex science behind them. It may not seem relevant for the average person, but understanding the things you buy gives you a better idea of which products are worth using and which ones are best avoided. I hope that this guide has been helpful, and that your repairs go off without a hitch.