Epoxy Adhesives: A Closer Look at the Pros and Cons

So you are considering using epoxy adhesives for your application. You’ve read about them and know what they actually are. But now you want a little more information.

You want advice from someone who knows all about epoxy adhesives. You want to know what makes them special, but also what features you should be aware of first.

Here at Forgeway, we’ve been manufacturing industrial adhesives for over 25 years. The very first adhesive we manufactured was an epoxy adhesive. We know epoxy adhesives inside out.

In this article, we are going to go over the advantages and disadvantages of using epoxy adhesives. By the end of the article, you will have a better idea of epoxy adhesives and whether they could be a good fit for your application.

What are the advantages of using epoxy adhesives?

Let’s assess what makes epoxy adhesives such a good adhesive option. The main advantages of using epoxy adhesives are their high strength, versatility, and durability.

This section will go over those advantages in more detail.

Epoxy adhesives are the strongest adhesives

One of the biggest advantages of epoxy adhesives is their ability to achieve exceptional strengths. Some formulations can be much stronger than other chemistry types, such as acrylics or polyurethanes. 

In applications where the adhesive needs to withstand high levels of stress or pressure, epoxy adhesives are often the first option you should explore.

Some epoxy adhesive formulations can achieve strengths up to 60 MPa which is comparable to that of a weld. So, if you are concerned that structural adhesives can’t match the strength of a weld, epoxy adhesives will put your mind at ease.

Epoxy adhesives are very versatile

You can use epoxy adhesives to bond a wide range of materials, including metal, wood, glass, and many types of plastics. This means that they can be used in a wide range of applications, from automotive repairs to the construction of aircraft.

Structural adhesives are used in the aerospace industry

The versatility also means you can get adjusted formulations to suit your requirements. For example, if you need an epoxy adhesive with a very fast cure time, it’s possible to get this variation.

However, whenever you adjust the specification of an epoxy adhesive to improve one characteristic, it is often at the expense of another characteristic. The best example of this is strength and flexibility.

If you want a highly flexible epoxy adhesive, you will have to sacrifice some of the strength. This just means that you need to determine which characteristic is more important to you.

Epoxy adhesives are often very durable

In some applications, the adhesive will experience harsh environmental conditions. Epoxy adhesives will often have great chemical and temperature resistance. 

This means that if the adhesive is going to experience chemical exposure (like when used in a fuel tank), an epoxy adhesive is the best fit as those chemicals will not damage the integrity of the bond.

Similarly, when the adhesive is exposed to high temperatures (like in an oven), it will need to withstand those temperatures. If the adhesive cannot withstand those temperatures, the bond will fail.

Epoxy adhesives tend to have the best heat resistance. So if you need the bond to withstand high temperatures, epoxy adhesives are likely the best option for you.

Aircraft oven using epoxy adhesives
Aeroplane ovens will need a temperature resistant adhesive

What are the disadvantages of using epoxy adhesives?

But epoxy adhesives have a few drawbacks too; they will often take longer to cure, will require surface preparation, and can carry health and safety concerns. However, we will discuss these disadvantages in more detail.

Epoxy adhesives have a longer cure time

One of the major disadvantages of epoxy adhesives is their tendency to have a long cure time. Some formulations can cure quickly and be ready for use within minutes or hours. 

However, most epoxy adhesives typically require several hours or even days to fully cure. External factors will also affect the cure speed of epoxy adhesives.

epoxy adhesives can take a while to cure
Uncured glue

Temperature plays a very large role in the cure of some epoxy adhesives. If the temperature around the working area is below 10℃, you may find that the adhesive doesn’t cure at all.

So if you are working on a project that requires a quick turnaround time, you may want to look at alternative adhesives such as acrylic adhesives. Having a slow-curing adhesive can delay the completion of the project and increase labour costs.

Epoxy adhesives can cause sensitisation

Epoxy adhesives can pose health and safety risks. Many epoxy adhesives contain chemicals that can be hazardous to handle. Whilst the level of risk will vary depending on the type of epoxy adhesive, you should be aware of the risks that you could face.

Skin contact is the most common route of exposure for epoxy adhesives. Generally, the epoxy resin can cause skin sensitisation over time if you are exposing them to your skin.

The epoxy hardener will not only be a skin irritant but also corrosive. You should take care when handling either resins or hardeners (or both). Some variations can cause irritation or allergic reactions if they come into contact with the skin or eyes.

This risk isn’t something that should put you off using epoxy adhesives. The packaging will always alert you to any risks posed. The use of proper protective equipment will help mitigate these risks when working with epoxy adhesives.

You will need to wear PPE when bonding with epoxy adhesives

You will have to prepare the surface before bonding with epoxy adhesives

Another disadvantage of epoxy adhesives is the need for surface preparation. Once again, the amount of surface preparation will depend on the variation of epoxy you are using. 

Nonetheless, you will need to clean and abrade the surface to achieve a strong bond with most epoxy adhesives. Whatever structural adhesive you are using, you must ensure the surfaces are free of dirt, grease, and other contaminants. 

But with epoxy adhesives, you will often have to take this one step further. This can be a time-consuming and labour-intensive process, and if it is not done properly, it can result in a weak bond or failure of the adhesive.

epoxy adhesives will need surface preparation for bonding

Epoxy adhesives; are they a good fit for you?

Without knowing your exact application requirements, it’s very difficult to tell you whether epoxy adhesives are the best choice for you. Now that you know the advantages and disadvantages of epoxy adhesives, it will be easier for you to decide for yourself.

However, you may still be struggling to decide. Here at Forgeway, we manufacture epoxy adhesives. We have helped guide companies just like you on the best adhesive choice for their application. 

Epoxy adhesives are one of the most reliable adhesives you can choose from. If you need a high-strength, durable adhesive that you can adjust, we would always recommend using them. 

But this is your decision. If you want a fast-curing adhesive, that doesn’t require surface preparation, we recommend looking at alternative structural adhesives.

When it comes to looking at alternatives, methyl methacrylate adhesives (aka acrylic adhesives) are often compared due to their competing levels of strength.

If you want to compare epoxy adhesives versus methyl methacrylate adhesives, read the article below and it will help you make that comparison.

Or, if you want the help of an adhesive expert, reach out and a member of our team will be happy to help you decide.

Choose an Epoxy or a Methyl Methacrylate adhesive? Find out here