Different Types of Epoxy: A Comprehensive Overview

Understanding the basics of an epoxy resin requires touching on a few chemistry basics. Reagents are a compound or substance that help produce a reaction. An epoxy group is a specific arrangement of two carbon atoms that are bonded to one oxygen atom.

Why is all that important? Because epoxies are created from a group of reagents that contain an epoxy group. The atoms from that group can react with essentially any other substance. That makes it ideal to use in applications alongside a hardening agent for curing, a process where the epoxy resin transforms from a soft liquid to a hardened solid.

You don’t always need a hardening agent to get the desired result from an epoxy resin. It is possible to use a different chemical catalyst to produce the same behavior. However, that ends up being an expensive process. That’s why most people end up using epoxy resins with a hardening agent for a home or workshop project.

The epoxy reaction can be done at room temperature and does produce heat. It typically doesn’t produce enough to become a fire hazard unless you use excessive amounts of epoxy.

The use of epoxy resin started back in the early 1930s, right before World War II. Coston Greenlee filed for the first epoxy product back in 1943, but the widespread use of different types of epoxy didn’t take off until after the end of the war.

Epoxy resins have become essential in woodworking and other industries throughout the world. The process of curing produces reactions like the following that help them fill a wide range of uses:

1. They provide a strong chemical resistance — Products cured with epoxy resin tend to remain stable in high alkaline environments, though they can still be vulnerable to acids.
2. They bond with a large selection of surfaces — Epoxies became stable in many industries because you can use them to create a strong bond with so many different materials.
3. They add strength — Epoxy resins are good for situations where you need something flexible to help materials hold up against added stress.
4. They allow structures to keep their basic shape — Epoxy resins bond securely to most surfaces without moving them out of alignment.
5.  They resist corrosion — While your typical epoxy resin can’t completely stop corrosion, it can vastly slow down the process and make different exteriors a lot more resistant.
6. They work as insulators — Epoxy coatings are good for protecting different products against electrical damage.

Epoxies are used in manufacturing plastics, paints, adhesives, primers, sealers, and coatings. They’re also used to make flooring and other products used in various building and construction applications. As we touched on before, the laminated wood often used to build roofs, walls, and decks in a home or building contain epoxy.

You can also find different types of epoxy used in glossy outdoor coatings. They are often used in sealers used on concrete floors and in protective coatings required for industrial settings. Epoxy resins are capable of bonding with materials like glass, stone, metal, and even some plastics.

If you’ve ever walked across a dazzling flooring installation, there's a high chance that it is an epoxy floor. Many epoxy floors like terrazzo, chip, or colored aggregate are created by adding different colors and patterns inside an epoxy floor layer. You can also create an epoxy flooring surface that includes paint chips or other additives to keep a floor surface from being slippery.

Advancements in technology make it possible to create a sustainable epoxy layer from a blend of recycled glass, different types of epoxy, and other recycled materials. That allows manufacturers to create products like countertop surfaces that contain up to 90% recycled material.

There are also water-based paints available that contain epoxy. They can dry quickly and provide a robust epoxy coating to surfaces. Water-based epoxy paints are often used on cast steel, iron, and aluminum applications. The paint coating helps protect those items from exposure and more flame-resistant versus other organic solvent-based alternatives.

It’s easy for consumers to become overwhelmed by the many different epoxy product choices presented to them when they visit a hardware store. It helps to understand that those different products are modifications of a few core categories of epoxy.

1. Pure epoxy
2. Polyester resin
3. Epoxy acrylates

Let’s look at what they are and how they are typically used.

There are two different types of pure epoxy that you can find on the market.

1. One-compound Epoxy

A one-compound epoxy product, also called a one-part epoxy, is a resin that comes straight from a container. There is no need to do any mixing, meter the substance, or remove bubbles. One-compound epoxies contain latent hardeners that provide a limited amount of reactivity at room temperature. You will need to have a heat source available for curing.

Most one-compound epoxy products come with a heating element to start the curing process. Most single-compound epoxies take anywhere between 30 minutes to an hour to cure at temperatures of around 350 to 400 degrees Fahrenheit.

2. Two-compound Epoxy

A two-compound epoxy is made up of two parts. The first is the base resin, and the second is the hardening agent. You will need to mix the two together in a thorough way. If you don’t mix the two-compound epoxy properly, that could cause problems with curing when you apply it to an application. Mixing the two parts creates a heat reaction that leads to curing.

You also want to make sure that there are no bubbles visible in your mix. Not only can they make the mixture visually unappealing when you apply it to a surface, but the bubbles can make the epoxy bond weaker and create a brittle surface that doesn’t serve your purpose.

Two-compound epoxy products typically form a slightly stronger bond than one-compound epoxies. That’s likely why they are more commonly found in a woodworking shop or used in an at-home product. It’s possible to cure a two-compound epoxy at room temperature. You may also choose to speed up the process by raising the temperature or adding a catalyst.

It can take around two to three hours for most off-the-shelf two-compound epoxies to become solid. Most experts recommend allowing a two-compound epoxy to cure for seven days at room temperature before you test its ability to hold up to pressure.

Uses of One and Two-Compound Pure Epoxy

You are more likely to find one-compound epoxies used for manufacturing purposes. It’s more efficient for that industry since manufacturers can heat other products on an assembly line simultaneously. Not having to mix two products saves time and equipment since the company won’t need to maintain the mixing equipment needed with a two-compound epoxy.

Two-compound pure epoxy products typically include primers, paste fillers, glues, resin, and consolidants. You get a more intense chemical reaction when you mix two different compounds, giving you a stronger bond. That’s why most home projects involve the use of a two-compound epoxy. 

Most woodworking and industrial processes involve the use of polyester resin. They are not a true epoxy, though the results produced by a polyester resin can be similar. Some advantages provided by polyester resins include:

• They resist water and are better at preventing damage from acids than epoxy resins
• They stand up well to age and weather and can last longer than epoxy resins
• They are heat-resistant
• They can be cheaper to maintain long-term than epoxy resins
• There is not a lot of shrinkage during the curing process

However, there are some limitations when it comes to polyester resins:

• They can be harder to mix than a two-part epoxy resin
• They can have a smell that many people find unpleasant
• The toxicity of the mixture requires the use of breathing apparatus and other protective equipment
• They are not able to bond to as many surfaces as an epoxy resin
• They can produce a weaker finish than an epoxy resin

Polyester resins are typically used for processes like building boats, creating parts for model making, or in swimming pools. You’ll also find polyester resins used in various fiber composites. Poly resins are effective at binding with glass fibers because it has a high saturation effect. Other uses for polyester resins include:

• Home and construction materials
• Packaging material
• Appliances
• Furniture
• Aircraft and vehicles

An epoxy acrylate combines the main resistance properties found in epoxy and polyester resins. Epoxy acrylates tend to be cured with UV light versus at room temperature or using a heat source. That allows them to cure at a faster rate than regular epoxy resin, making them more durable. The fast curing time can also make it easier to work with an epoxy acrylate than an epoxy resin.

Another good thing about epoxy acrylates is that they provide the highest chemical-resistant level of the different types of epoxy. You can also mold epoxy resins in different ways to accentuate different properties.

It is possible to modify the resin portion of two-part epoxies. It’s possible to add dye to the resin to match the underlying material better or create a different shade for the finish. You can find professional tints to add to a resin at many local hardware stores or by searching online. You can also add fillers to make the epoxy thicker. Some people do this in situations like replacing a section of rotting wood or creating a new cast. 

It’s recommended that you use safety glasses and wear gloves whenever you are working with an epoxy. You want to avoid getting any of the substance on your skin where it might stick. Wearing protective gear also lowers the chances of you having an allergic reaction to different epoxy types. Make sure you work with epoxies in a well-ventilated area. Consider using a respirator-type mask if you don’t feel that is enough to keep you from inhaling toxic fumes.

It’s always a good idea to learn as much as you can about different epoxy types before you start working with them. We hope this guide helps you in those efforts.