Polyurethane vs. Epoxy (Which One Is More Durable?)

When choosing paint for your floor or concrete, most painters will advise you to go for epoxy or polyurethane. But what’s the difference between polyurethane vs epoxy?

Polyurethane is a clear plastic common for its flexibility and elasticity. Polyurethane can cope with temperature changes and high traffic areas which makes the finish very durable.

Epoxy on the other hand is a glossy and strong coat commonly used as an undercoat or part of prep work before applying a sealant. This is because epoxy is a two-part paint with great adhesive qualities. Epoxy paint is also not as flexible or elastic as polyurethane since epoxy is harder and rigid.

Also, the elasticity of polyurethane makes it cope better in hot areas than epoxy. This post reveals more about the differences between polyurethane and epoxy. So let’s dig deeper. First, let’s check out what epoxy paint is used for.

What is Epoxy Paint?

What is Epoxy Paint?

Epoxy paint is a strong paint that usually comes in 2 parts. You have the resin and the hardener. Both parts of the epoxy have to be mixed in the right ratio, usually 1:1 to be used. The reaction between the two parts when mixed creates a very strong film known as epoxy.

There are also 1 part epoxy paints that don’t have to be mixed to be used. But, 1 part epoxies aren’t as durable or strong as 2 part epoxies.

Epoxy paint comes in different variations. You can get chemical-resistant epoxy, flexible epoxies, fast-setting epoxies, and the likes. Epoxy paint has great bonding traits. The paint bonds even better to concrete and masonry. The increased binding is due to the chemical reaction of the paint when the two parts are mixed.

Epoxies are also known to have a thick flow which means the paint takes a long to dry. For instance, 2-part epoxy flooring can take up to 7 days to cure enough to be subjected to high traffic and automobile weight.

However, epoxy paint has a few flaws. Epoxy paint tends to produce strong offensive fumes when used. The fumes are produced from the reaction of epoxy chemicals with oxygen. Also, epoxy is not able to cope with temperature changes since the paint is rigid.

Now let’s check out polyurethane paint and its uses.

What is Polyurethane?

What is Polyurethane?

Polyurethane is a plastic sealant used for mainly the protection of the material or finish underneath. Polyurethane is produced from polyols and isocyanate or diisocyanates. These compounds react with the polyol to create a plastic in a liquid form known as polyurethane.

When the polyurethane is applied, it dries to form a plastic. This plastic sheen is water-resistant, chip-resistant, and sometimes, UV-resistant. This makes polyurethane very durable.

Polyurethane is also more flexible than most top coats. Polyurethane contains plasticizers like tricresyl phosphate (TCP) that make it thrive in hot areas or when exposed to heat.

Polyurethane also has a quick-drying time. Water-based polyurethane for instance cures in less than 48 hours. To top that, polyurethane also has chemical-resistant properties.

Polyurethane also boasts of a wide variety of finishes as you can get satin, medium-gloss, and high-gloss polyurethane.

Polyurethane vs Epoxy: Head to Head

So which of these paints is better? Let’s go deeper into the characteristics of both paints to bring out their differences, strengths, and weaknesses.

Paint Make-Up

Paint Make-Up

Both sealants have a different make-up and formation. Polyurethane is gotten from the reaction between polyols and diisocyanates or isocyanate compounds. Epoxy on the other hand is gotten from the reaction between a resin and hardener which have to be mixed manually.

The difference in paint make-up gives both finishes some different features. For instance, epoxy is known to be thicker than polyurethane because you have to mix two equal coatings (or parts) to make epoxy.

Flexibility

Paint flexibility refers to the elasticity of the paint. Polyurethane is more flexible than epoxy. This is because polyurethane has plasticizers in the paint coating.

The plastic nature of the polyurethane film makes it stretch and contract based on temperature changes. This gives polyurethane improved flexibility.

Epoxy paints on the other hand are more rigid and hard. Epoxy paint coatings are hard, rigid, and brittle. This is why you are more likely to notice hairline cracks in the epoxy finish.

Paint Drying

Polyurethane paint dries faster than epoxy. Water-based polyurethane for instance dry in less than 2 hours and you can use the finish in about 24 hours.

Epoxy however takes longer to dry. Oil-based epoxy coating can take well over 6 hours to dry. You’ll also be advised to leave the epoxy paint for at least 3 days before using it or cleaning it. This is because epoxy paint takes longer to cure.

Paint Adhesion

Paint adhesion refers to how well the paint bonds to the material. In terms of paint adhesion or binding, epoxy is better. This is because epoxy is made from two compounds that determine paint adhesion; a resin and hardener.

When mixed, the epoxy paint that is produced will bind well to any material especially hard surfaces like concrete and masonry.

Though polyurethane also adheres brilliantly, it doesn’t stick as well as epoxy, especially two-part epoxies. One reason polyurethane doesn’t have the best binding properties is that polyurethane coating doesn’t penetrate wood as much as other sealants. You should know that for both paints to stick, adequate surface preparation is key.

UV-Resistance

UV resistance refers to how well the paint thrives when exposed to UV lights. In terms of UV resistance, polyurethane is better than epoxy. Though polyurethane isn’t usually UV-resistant, there are exterior polyurethane products designed with additives to make the paint coating thrive under UV exposure.

Epoxy paint on the other hand doesn’t have such additives. On its own, epoxy isn’t UV-resistant. This is why epoxy is usually sealed with top coats like exterior polyurethane that offer UV resistance.

Durability

Both top coats are hard and strong but it takes more than paint strength and thickness to be durable. For paint to last long, the finish must be able to adapt to changes. Polyurethane can stretch and contract.

This makes the paint coating thrive in cold, warm, and hot temperatures. Polyurethane is also water, chip, and UV-resistant. Also, it has a higher cross-linking density. So polyurethane lasts longer than epoxy.

Epoxy paint however also lasts long but not as long as polyurethane, especially when used on high traffic areas or under UV exposure. Since epoxy is rigid, it’s not flexible enough to cope with temperature changes. Epoxy is also not UV-resistant.

Chemical-Resistance

Polyurethane has a more chemical make-up and as such is more chemical-resistant. Epoxy is more of a binder so chemical spills on epoxy will negatively impact the finish. Epoxy can even be damaged by the organic acids in food and drinks.

Paint Additives

Paint additives refer to compounds that are added to the paint coating to improve the finish. Polyurethane has more paint additives than epoxy. Some of the additives in polyurethane include plasticizers for elasticity, REPI liquids for heat resistance, and the likes.

Some polyurethane products even contain anti-microbial additives to prevent mold and bacteria from growing on the finish.

Epoxy paint however has a very low level of additives in the paint. With most epoxies, all you get is a resin and hardener. The additives in epoxy paint are usually to reinforce the strength and toughness of the finish.

Heat-Resistance

Polyurethane boats of better heat resistance than epoxy. Again, this is due to the flexibility of the polyurethane paint. Polyurethane can handle the heat of over 220 degrees Fahrenheit.

Epoxy paint however can’t handle that much heat. Most epoxy paints can’t handle more than 150 degrees Fahrenheit of heat.

Paint Hardness

Polyurethane is not as hard as epoxy paint. Polyurethane has a thick plastic-like texture which is softer than the hard sheen of epoxy paint especially two-part epoxy.

This is why you see two-part epoxies being used on garage floors. The hardness of epoxy makes it ideal for surfaces that will see heavy hitting.

Method of Paint Application

Polyurethane can be applied using a spray gun or a paintbrush. If you have good painting experience, you can apply polyurethane by wiping it on the material.

Epoxy paint however needs to be rolled on the flooring or furniture with a high-quality paint roller.

Paint Variety

You get more shades and types of finishes with polyurethane than with epoxy. With polyurethane, you can choose a water-based or oil-based paint. You can also choose a satin, medium-gloss, or high-gloss polyurethane finish.

However, with epoxy, you have a limited range of choices. All you get with epoxy is a strong and hard film since epoxy isn’t designed for decor or aesthetics.

Indoor or Outdoor Use

Polyurethane is more suited to outdoor use than epoxy. This is because polyurethane is more flexible and it has UV-resistant properties so polyurethane will be better on outdoor furniture or flooring. Epoxy is more suited to indoor use since it is rigid and not UV-resistant.

Now that you know the differences between both paints. Which of them should you get? This depends on a few factors. Let’s take a close look.

Should I Buy Polyurethane or Epoxy?

Before you make that decision, ask yourself a few questions.

How Much Is The Budget?

You should only go for paint that you can afford. Two-part epoxy resins cost over $100. Polyurethane wouldn’t cost you that much.

Are You Painting Indoors or Outdoors?

If you are painting outdoor furniture, it’s best to go with flexible and UV-resistant Polyurethane than rigid epoxy paint. You can use epoxy indoors but don’t use it in poorly-ventilated areas.

Where are You Painting?

For the kitchen and dining area, you can use Polyurethane since polyurethane sometimes has antimicrobial additives that prevent bacteria from growing. Polyurethane is a more hygienic option.

Do You Want To Paint Over High Traffic Areas?

If you are painting a patio or walkway where there will be heavy foot traffic, you should go with polyurethane as it’s flexible enough to withstand heavy use.

However, if you are painting a garage where the floors will experience heavy-hitting and dents, you should use hard epoxy paint.

That said, here is my advice. If you don’t mind the cost, it’s better to use epoxy and polyurethane. Is that possible? Let’s find out.

Related Read: Can You Put Epoxy Floor Over Paint?

Can You Use Polyurethane Over Epoxy?

Yes, you can use polyurethane over epoxy. This is a hack many painters use to get a good and strong finish on building exterior.

Since epoxy has better paint adhesion, it can be used on the material first as a base coat. Also, epoxy is much stronger and tough so it’s a great undercoat option.

When the epoxy has cured, it should be sealed with 1 or 2 coats of polyurethane. Remember, it takes longer for epoxy to cure so you might have to wait a few extra hours before sealing epoxy with polyurethane.

The polyurethane applied will be flexible as well as heat, water, and UV-resistant. So it can withstand changes in temperature and heavy use while the epoxy underneath serves as a strong undercoat for the entire finish.

Tip: The best polyurethane to use over epoxy is oil-based polyurethane.

Final Words

Overall, the main difference between polyurethane and epoxy is the flexibility of the polyurethane and the rigidity of epoxy.

Asides from that, both paints are durable and very ideal for surfaces that will see action and heavy use. The one you go for depends on your taste and needs.

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