How and when to use epoxy glue? | The N°1 clear guide

Epoxy glue is one of the many glues used in woodworking and is becoming more and more popular with passionate DIY-er as well as professionals.
If your project consists of wood, cement, metals, or plastics, or a combination of these, epoxy adhesive is a perfect choice. But is all epoxy the same? And can you use all epoxy to glue with?

The answer is no, not every epoxy is the same. To know how to use epoxy glue, you need to understand this type of glue. That’s where this in-depth, clear guide will help you understand what epoxy is and how to use it properly.
So you can get the best results for your project every time.

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What is epoxy glue?

Before we can dive in this article on how to use epoxy glue, it is a good idea to know what this type of adhesive exactly is.

Epoxy glue is a resin-based glue to which there is a hardener added. Usually, one speaks of a two-component adhesive, where the two components will be packaged separately, and the glue can be created by mixing the epoxy resin and the hardener.

Nowadays, many brands like for example Gorilla glues offer epoxy adhesives whose components are already has been mixed.
This makes using epoxy adhesive easier and faster to use.
The disadvantage of these already premixed adhesives is that they require a higher curing temperature.

Epoxy adhesives, or two-component adhesives, can often be used to bond materials when there is very high strength and durability required.

This adhesive can also be used as a gap filler, making it perfect for use if you need to carry out repair work and restorations.
Epoxy can be sanded, drilled, and painted, which is why this glue is becoming more and more popular for DIY projects.

After mixing the two components, the working time is only a few minutes, depending on the adhesive you use. In just a few minutes, the glue will already firmly bond the materials.
But to reach the glue’s maximum strength, you will have to give the glue a few more hours.

What are the properties of epoxy glue?

Next to wood glue, Epoxy glue is an often used adhesive in woodworking. Before you start working with epoxy adhesive, you need to know what the most important properties of this glue are.
That way, you can estimate whether Epoxy adhesive is the best choice for your project or not.

Below you will find a summary of the most important properties of epoxy glue:

• The connections made between two materials by epoxy adhesive have a high resistance to chemicals.
• Epoxy adhesive tends to absorb moisture.
• A transparent, opaque, or colored bond can be made with epoxy adhesive.
• Epoxy is a great electrical insulator
• Epoxy adhesive has strong mechanical properties.
• The bonding with epoxy is resistant to higher temperatures.
• Epoxy bonds very well with a wide variety of materials.

What are the different types of epoxy?

Not all epoxy is the same, they look similar but have different purposes. So if you want to glue with epoxy, it is important to know the difference. That way, you can determine which epoxy is suitable for gluing and which is not. Epoxy can be divided into 3 types,

• pure epoxy
• polyester resin
• epoxy acrylics

Pure epoxy

One component epoxy glue

Most people know epoxy adhesive as two components that have to be mixed together.
But did you know that there is also one-component epoxy glue?
The biggest reason you would choose this is the ease of use.
You can use this type of epoxy glue directly from the container without dosing, mixing, and removing air bubbles.

The disadvantage of this type of epoxy adhesive is that they require high temperatures to cure.
If you want to work with one-component epoxy, you will have to purchase a heating element to allow the glue to cure properly.

A one-component epoxy adhesive takes approximately between 30 minutes and an hour to cure.
This is noticeably longer than with two-component glue. Nowadays, there is also a one-component epoxy adhesive that can cure completely by ultraviolet light present in sunlight. Another drawback is that one-component epoxy glue has a slightly weaker bond than the two-part epoxy resins, and they tend to be a bit more expensive as well.

Two-component epoxy glue

The most common epoxy adhesive is the two-component epoxy.
It is a glue that can be used both at home and in the workshop, and therefore a handy glue to always have available.

The two components in this adhesive are the epoxy resin and the curing agent.
By mixing these together, a chemical reaction will be created that ensures that the glue hardens within a few minutes.

A two-component epoxy resin can cure easily at room temperature, but increasing the temperature can speed up the curing process.

Polyester resin

Another type of resin commonly used in woodworking and industrial processes is polyester resin.
Note that, although the end products are similar, polyester resin is not epoxy, and is used for other purposes than glue-ups. Polyester resin can be used in woodworking for, among other things, making stylish tabletops. 

Epoxy acrylates

An epoxy acrylate contains both the properties of epoxy and the properties of polyester resins, so it is a kind of combination of the two.
This form of epoxy is also not suitable for gluing, so it will not be discussed further.

Epoxy acrylates are an excellent fit for industrial wood, joinery, furniture, top coatings for flooring, and fillers.

what is epoxy glue used for?

As you could already discover in the properties of epoxy above, this glue can be used for joining many materials.
It is therefore a multipurpose adhesive for the workshop.

Below, you will find more information and can see if you can use this glue for that specific project you are working on.
Befor using epoxy glue, be sure to read my article Epoxy Glue Safety Precautions: What You Need To Know Before Using It.

Epoxy glue for plastic

Household appliances, toys, garden furniture … all things that are mainly made of plastics and can break over time.
That is why it is recommended to always have epoxy adhesive on hand because this glue is perfect for carrying out these repairs.

Plastics need a quick bond, which is why epoxy adhesive is one of the best choices for bonding this material.

Epoxy glue for metal

There are specialized epoxy adhesives made specifically for bonding metal. You can attach metal parts to each other, secure bolts and screws, and even repair unpressurized pipes.

The epoxy adhesive cures to a metallic gray color and after complete curing can be sanded or drilled.
In addition, it is also water-resistant.

Epoxy glue for wood

These adhesives can be used perfectly for gluing wood or filling gaps in the wood.

Personally, I’m going to use epoxy glue when I want to bond wood to another material.
In just minutes, I have a strong bond that I wouldn’t have using other adhesives.

Epoxy glue for concrete or cement

If you have cracks in concrete parts or if you need to rebuild concrete surfaces, you can easily repair them with the right epoxy.
For all these jobs, you can use the same epoxy glue as for gluing metal. The advantage is that after curing the glue turns gray and in many cases, you will therefore hardly notice the difference, between the glue and the concrete.

What cannot be glued with epoxy glue?

Epoxy resin adhesives adhere to almost all materials, but there are a few exceptions.

Epoxy glue cannot adhere to polypropylene, polyethylene, Teflon, Vinyl, rubber, and nylon.
Poor bonding will occur when using epoxy glue on polyvinyl chloride, acrylic, and polycarbonate plastics.
Also, where you have used silicone-based products, epoxy glue will not bond.

The way in which you can tell whether epoxy glue will adhere to the material you want to glue is simply by testing it yourself on a scrap piece.

Let it dry for about 24 hours, and test out the result to see if the bond will be usable for your project.

How to use epoxy glue?

Now that you have learned more about epoxy glue, you can make the right choice of which glue is best suited for your project.
However, before you start using epoxy glue, it is important to consider some safety considerations that can help you work safely with epoxy.

• Wear eye protection when using epoxy adhesive
• Ventilate the room when using epoxy adhesive
• Watch out for allergic reactions

Although epoxy is a relatively safe adhesive to use, it is recommended to wear eye protection.
If there is a small chance that your eyes will come into contact with the two-component adhesive, it is best to rinse them immediately and thoroughly and seek medical attention.

When processing Epoxy, toxic fumes are virtually absent because it contains no solvents.
Ventilation is therefore not an absolute priority, but always ensure natural ventilation during work.

When using epoxy, you should also be more careful with signs of an allergic reaction.
If these should occur, stop working immediately.

For more tips on working with epoxy, see the FAQ section below.
Smaller questions will be answered in that section.

What is the application temperature of epoxy glue?

The most ideal application temperature to use epoxy adhesive for bonding materials is between 50 °F (ca. 10 °C) to 100 °F (ca. 38 °C).
If you use epoxy glue at temperatures that are higher or lower, a good connection can no longer be guaranteed.

What is the service temperature of epoxy glue?

The most ideal temperature to store epoxy adhesive is between 15 °C (60°F) to 30°C (85°F).
If your epoxy glue has spent a period of time in a higher or lower temperature, stop using it and throw it away. There is a good chance that the bond will not have full strength.

How to mix epoxy glue?

Two components must be mixed to obtain a usable adhesive.
The resin and the hardener must be mixed together at a ratio of 1:1 to form a homogeneous mixture.

How I personally do this is the following:

• On my workbench, I stick a few strips of painter’s tape. On this tape, I push the amount of glue I estimate I need.
• I mix the two components with a plastic spoon. It is very clear to see when you mixed these components well, keep an eye on the color and texture of the glue.
• Then I apply the glue to the parts that I want to connect with the plastic spoon.
• I don’t throw away the painter’s tape yet, and use it to check whether the glue has hardened enough. For example, I must not touch the glued parts where there is no chance that the bond would fail.

I use the plastic spoon because it is easy to clean and eventually replaceable after many uses. I must admit that I still use the same spoon in the many years since I have started using epoxy adhesive.
For a more detailed guide on how to mix epoxy, go to my article How to Mix Epoxy Glue Properly: A Clear Step-by-Step Guide to Success

How to store epoxy glue?

Store epoxy adhesive in a cool, dry place around room temperature (21°c – 70°F).
Always keep resin and hardener separated, therefore, always use the enclosed cap.
Before applying this cap, always wipe the tip with a dry cloth and use a different cloth for both the resin and the hardener. 

There is so much more to tell about storing expoxy glue. In my article How To Store Epoxy Glue: Best Practices To Ensure Longevity I go in much more detail. So if you want to get the most out of your epoxy glue, do not miss that important information.

Conclusion

Epoxy glue is an incredibly reliable, impermeable, and robust adhesive that is routinely employed for woodworking and other fields due to its remarkable resilience to water and many chemicals. Furthermore, its clear and see-through nature makes it a top pick for activities where aesthetics matters much.

It is essential to utilize epoxy glue correctly and adhere to the manufacturer’s directions in order to accomplish optimal bonding. This necessitates selecting the appropriate type of epoxy for the task, prepping the surfaces to be bonded accurately, and mixing together the components of epoxy in the accurate ratios.

If you want to discover other adhesives regularly used in woodworking, my article “This is why CA glue is a popular glue for woodworking | All about CA glue” is something worth a look. CA glue, also termed cyanoacrylate adhesive, is a strong and fast-drying substance that woodworkers often choose due to its copious bonding properties and its capacity to fill in cracks. With an understanding of the features and advantages of various adhesives, you can make the most suitable selection for your woodworking project and get the outcomes you wished for.