Can Epoxy Be Used Outside?

A Guide to UV Protection for Outdoor Epoxy Projects

The surest way to ruin that glossy epoxy countertop or table top you spent hours perfecting is to let it cure, put it outside, and let the blazing sun and standing rainwater wreak havoc on the surface.

Epoxy cures into a hard and durable surface, with high resistance to abrasion, corrosion, solvents and chemicals. But on its own, it's not able to withstand harsh sun, not even if you add mica powders or pigments to the epoxy.

How does sunlight damage epoxy? Continuous UV exposure will degrade and discolor an epoxy surface, turning it yellow, hazy and making it less glossy. So can epoxy be used outside at all? Yes, as long as you choose a UV-stable formula and protect it properly. In this post, we'll explain how to protect your outdoor epoxy projects from UV damage so that with proper maintenance, their beauty will last for years.

Can Epoxy Be Used Outside?

Most epoxy is not UV resistant on its own. It's simply the nature of the chemicals that make up epoxy resin and hardener — they become unstable when exposed to UV (ultraviolet) light. So yes, epoxy can be used outside, but you need to protect the surface with a coating that is UV stable. This matters not only for outdoor epoxy surfaces, but for epoxy surfaces in rooms with lots of natural light.

Some epoxy products are formulated to help resist damage from UV exposure, but even with these UV-resistant epoxies, we recommend increasing the UV resistance further by applying a clear, UV-stable top coat.

Is Epoxy Resin Weather Resistant?

Once fully cured, epoxy is waterproof and holds up well against rain, humidity, and temperature swings. That durability is part of why it's used to coat boat hulls and outdoor furniture in the first place. The part of "weather" that gives epoxy trouble isn't moisture — it's sunlight. Without UV protection, continuous sun exposure will break down the surface well before rain or humidity ever would.

Will Epoxy Resin Fade or Yellow in the Sun?

Yes, if it isn't protected. Unprotected epoxy left in direct sunlight will gradually yellow, haze over, and lose its gloss as UV rays break down the resin at a chemical level. A UV-stable formula slows this process considerably, and a protective topcoat slows it further, but no epoxy is completely immune to the sun over the long term.

What Finishes Should I Use for UV Protection on Epoxy Surfaces?

A UV-resistant urethane or varnish provides maximum protection against sun damage. TotalBoat Halcyon clear gloss varnish, for example, provides maximum  protection on cured epoxy surfaces and is one of the most reliable ways to prevent yellowing on an outdoor piece.

What's the Best Epoxy to Use Outdoors

Not all epoxy is created equal when it comes to standing up to the sun. For outdoor projects, look for a formula that's specifically engineered with UV stabilizers that resist discoloration better than standard casting or table top epoxies right out of the gate. That said, even a UV-stable epoxy performs best with a clear, UV-resistant topcoat on top. Pairing the right base resin with a maintenance coat of Halcyon varnish gives outdoor pieces the longest-lasting clarity and gloss.

TotalBoat epoxies WITH UV inhibitors:

• • TableTop
  • ThickSet
  • Fathom
  • Artist Resin

TotalBoat epoxies WITHOUT UV inhibitors:

• • High Performance
  • Traditional 5:1 Marine
  • Wave and Marble

How to Protect Epoxy from UV Damage

• Make sure the epoxy is completely cured before you apply a UV-resistant coating.

• Scuff-sand the cured epoxy surface lightly with an  abrasive pad.

• Remove residue and surface contaminants by wiping with a clean, lint-free cotton rag dampened with TotalBoat Dewaxer & Surface Prep solvent. Allow to dry completely.

• Apply a UV-stable finish coat, as directed.

Can Epoxy Be Used on Wood Outdoors?

Yes, and wood is one of the most common surfaces for outdoor epoxy projects like tables, countertops, and bar tops. The key is making sure the wood is completely dry before you start; trapped moisture can cause the wood to expand and contract with outdoor temperature swings, which puts stress on the cured epoxy and can lead to cracking. Once the wood is properly dried and sealed, it is as vulnerable to UV rays as any other epoxied surface, so don’t skip applying a topcoat.

How Long Does UV Protection Last on Outdoor Epoxy?

How long your finish holds up depends on the quality of the topcoat you apply and how well it maintains its filtering capabilities over time. Only absorbed light can trigger the photochemical processes that cause irreversible damage, so keeping that protective layer fresh is the most important thing you can do for an outdoor piece.

As a general guideline, plan to reapply your topcoat every one to three years depending on how much direct sun the surface gets. Pieces in full, year-round sun will need refreshing closer to the one-year mark, while shaded or seasonal pieces can often go closer to three.

It's also worth keeping in mind that sun intensity varies significantly by location and time of year. At lower latitudes nearer the equator, rays travel a shorter distance through the atmosphere, so less radiation gets absorbed before it hits your surface. The same is true at higher altitudes, where the atmosphere is thinner.

Seasonally, spring and summer bring the strongest exposure, while winter is comparatively gentle. As a point of reference, 10 minutes of Florida summer sun may equal a full month of winter sun exposure in Maine.

Depending on where you live, you might need to reapply more often than the general guideline suggests. With proper care, a well-protected surface can last outdoors for years.

Do All Outdoor Epoxy Projects Need UV Protection?

Your epoxy table top or countertop doesn't need UV protection as long as it will never be exposed to direct or indirect ultraviolet light . But if there's even the slightest chance that the surface will be exposed to the sun, we recommend that you apply a urethane or varnish over the cured epoxy surface.

If you have any questions at all about working with epoxy or protecting your epoxy projects from UV damage, call our Tech Support Team at (888) 986-6623 or reach out to info@totalboat for answers.