Is epoxy just plastic?

Think of epoxy as a special kind of thermoset plastic. Now, you might be wondering, “Is epoxy just a fancy name for ordinary plastic?” The short answer is no; it isn’t.

Thermosets are different from thermoplastics because they are unable to be remelted and recycled like thermoplastics.

In order for the process of recycling to work on thermoplastics, an external source of heat must be applied to separate the polymer chains from each other so that the adhesives can be removed from the material and it can then go through recycling.

Some common examples of thermosets include urethane foam insulation and fiberglass composites. Epoxy resin systems have been around since World War II and have become increasingly popular over time because they come with several beneficial characteristics.

One benefit is their flexibility in application with many different types of materials including metals, stone, wood, glass, and concrete surfaces.

Is epoxy just plastic?

When you’re trying to make sense of the difference between epoxy and plastic, it can be helpful to think about how each is made, as well as what they look like when they’re finished being made. If you break down the word “epoxy,” you’ll see that “epoxy” means “to glue together.”

This makes sense because although epoxy will harden into a solid material (more on this in a bit), it starts out as liquid. So what is plastic? Unlike epoxy, which starts out as a liquid, plastic starts out as a powder. To create plastic, the powder goes through an extrusion process that heats and shapes it into its final form.

Epoxy comes from the family of materials known as thermosets—a group that also includes things like rubber bands, rubber cement, and chewing gum.

Thermosetting plastics are so named because they will set permanently once they’ve been heated and pressed together.

And when we talk about plastics setting permanently, that means the resulting shape can’t be changed by heating or by pressing it again.

We say thermosetting plastics have cross-linked bonds (which use both covalent and ionic bonds). So why does this matter for understanding whether epoxy is plastic? Because most plastics are thermoplastics materials that become soft or even liquid when heated up sufficiently.

Thermoplastics don’t have cross-links (they only use covalent bonds), which makes them flexible enough to reshape without breaking chemical bonds!

What kind of plastic is epoxy?

Epoxy is a thermosetting polymer, which means it forms a hard, rigid plastic when cured. It’s not a type of plastic, it’s actually its own unique substance.

You might be familiar with another type of polymer, thermoplastic. These are the plastics that can be melted and reformed to make things like PET bottles and 3D printer filament. Thermoset plastics like epoxy cannot be melted; instead, they form into hard shapes when heat and/or pressure are applied. What’s more, once set they cannot be softened again by reheating as thermoplastics can.

This makes epoxy an excellent material for coating applications where you need resistance to impact, abrasion, and corrosion things we’ll talk about later on in this guide!

What is epoxy made of?

While you may be tempted to start mixing your epoxy resin right after it arrives, it’s important to understand exactly what epoxy is made of and why it’s used.

Epoxy resins are actually a class of chemicals, not one specific chemical. The main ingredients of most epoxy resins are bisphenol A and epichlorohydrin.

Epoxy is made from a base and a hardener that together form an exothermic reaction that results in the desired polymer (the material used for making coatings). The base is usually bisphenol A, which is a liquid form of plastic.

Is resin always plastic?

You may be surprised to find out that not all resins are plastics. Instead, resin is a natural material. It’s the sap that flows inside trees when they’re alive. This liquid hardens and turns into a solid once it comes in contact with air.

Depending on how you work with it, resin can be used to make plastic or it can be used to make varnish for your floors or furniture.

Epoxy resin is actually a type of plastic, but other types of resins like dammar and copal are not considered plastics at all.

Does epoxy resin stick to metal?

No, epoxy resin is not just plastic. It is a thermoset type of plastic that, once cured (hardened) stays in its current solid-state forever. It will never become a liquid again and it isn’t affected by heat or cold.

Epoxy resin can stick to metal beautifully and has many applications in the construction of metal boats. Because the curing process creates no heat, the epoxy is safe to use with any metal that doesn’t react badly with epoxies such as copper and brass (it will cause corrosion).

Epoxy resins are also used to create high gloss finishes for metal sculptures and objects such as coasters, trays, or keychains.

How harmful is epoxy resin?

Is epoxy resin harmful? That’s a common question for anyone who isn’t familiar with it. Here are the facts:

  • Epoxy resin is not harmful if used properly. It can be harmful if inhaled, so always use it in a well-ventilated area or with a respirator and gloves. In some cases, skin irritation may occur. However, epoxy resin is not harmful if ingested and is not harmful to the environment (SDS information here). It does not leach chemicals into the water and is even used for food-grade applications such as countertops and kitchen islands. Epoxy will also not harm fish (MSDS information here).

Is epoxy waterproof?

Is epoxy waterproof? Yes, epoxy resin is waterproof. In fact, that’s one of the reasons it’s so widely used in marine applications.

Epoxy is used as a sealant to waterproof decks and boats. It’s also used to coat floors and walls in wet areas like bathrooms because it seals out moisture and can be made stain-resistant by adding a non-slip aggregate or texture to the topcoat.

Is epoxy natural?

Of course not! Epoxy is a man-made product and is not considered a natural substance. It is made from synthetic materials, so it’s safe to say that epoxy would be considered plastic.


You now have a basic understanding of epoxy. In short, epoxy is made up of petroleum-based products, which makes it a type of plastic.

There are different types of epoxies that are used for different applications, but all require mixing two or more elements in order to form an end-product that can be used in various ways.

Epoxy is not natural, but it typically lasts much longer than other materials (especially wood), requires less maintenance and upkeep over the years, and can be made to look like many other materials (such as granite).

It’s not waterproof or harmful, but if you’re looking for a way to coat metal items such as toolboxes with an attractive finish that will last for years, then epoxy might just be what you’re looking for.

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