Epoxy is a popular material in crafts and woodworking. Despite being used for things like home decors and even to waterproof outdoor wood, there are still a ton of questions about how to properly use epoxy and make it look good.
When working with epoxy, it is easy to follow the instructions on the package and think that you are done. And, typically, this is enough. But you can take your projects to the next level by learning how to finish epoxy properly, especially if you want to add shine or to offer some extra protection to the material.
So, how do you finish epoxy? There are a few different ways to finish epoxy, depending on the result you’re looking for. If you want to create a clear and polished surface, sanding and polishing is the perfect way to finish epoxy. If you want it to be UV and weatherproof, you’ll need a polyurethane finish.
In this article, let’s learn more about how to finish epoxy properly.
Does Epoxy Even Need A Topcoat?
One of the most important questions that you should ask yourself when it comes to using epoxy is, “Does it need a topcoat?” Epoxy, when it is completely cured, actually dries to become a durable, water-resistant surface on its own, so why does it need a finish in the first place?
While epoxy is highly water-resistant (up to 20%), which is usually enough for most projects, additional sealants are often required to protect against high humidity, rain, and other factors. This is true when you have waterproofed outdoor wood with an epoxy finish.
In areas with heavy rainfall, an additional sealant should be applied to epoxy to prevent the accumulation of organic contaminants that can lead to degradation and rot.
Epoxy isn’t strong enough to completely protect your wood from all of these harsh conditions, so using a stronger sealant over it is always a good idea.
In addition, epoxy is not resistant to the effects of sunlight, and it can actually become foggy or discolored after being exposed to sunlight for a long time. If you are planning on leaving the wood outside for an extended period of time, applying an additional coat of UV-resistant sealant can stop further degradation and discoloration.
Most of the time, epoxy is highly durable on its own, so you don’t need to apply any other finish on top of it. This is true if you’re only using the epoxy as a finish for indoor wood or decor placed inside the home – there’s really no need to add more protection to the epoxy.
However, if you find that the epoxy is dull, discolored, or weathered, you can also apply a little bit of polish to restore it. Let’s take a look at two ways to finish epoxy below.
Two Ways To Finish Epoxy
Below are the two best ways to finish epoxy. The first is sanding and polishing, and the second is applying polyurethane.
Method 1: Sanding & Polishing
This method is the simplest and easiest way to take your resin art project to the next level. After completing a resin art project, getting rid of excess resin and polishing it are two very important steps to give you a beautiful, shiny finish.
This process first involves carefully sanding the resin to smooth out the surface. Then, you can apply a layer of polish over the sanded surface to add some shine to the epoxy and provide some extra protection.
Epoxy isn’t picky when it comes to polish. Most types of polish that work with metal will also work with epoxy. You can also look for a polish that is specially formulated to work with epoxy, which is highly effective at smoothing out scratches and imperfections.
Note that this process can only work after the epoxy is completely cured, which, depending on the epoxy you’re using, can take anywhere from 48 hours to a week after the epoxy is applied.
What you’ll need:
- Coarse sandpaper
- Fine-grit sandpaper
- Polish for epoxy
- Microfiber cloth
- Optional: polishing tool and a drill
- After your epoxy item is completely cured, wash it with soap and warm water to remove any residue on the surface. Make sure not to use hot water, as it can damage the epoxy.
- While the surface is still wet, go over the area with coarse sandpaper to smooth out any bumps. Add more water if it becomes too dry.
- Then, go over the area with the fine-grit sandpaper to smooth out any marks and scratches created by the coarse sandpaper. After sanding, you can dry off the surface before applying the polish.
- Pick up a little bit of polish for epoxy with the microfiber towel and buff it into the surface using a circular motion. Make sure to work quickly and don’t linger on any particular area, as it doesn’t take much to shine the surface. If you have a big surface, it might be more efficient to use a polishing tool attached to a hand drill. If you don’t have that, it will take a bit longer but won’t affect how the final result will look.
- After applying the polish, you can wash off the area to remove any residue on the surface. Your epoxy resin should now have a shiny and pristine finish!
Method 2: Polyurethane Finish
A polyurethane finish is recommended on top of epoxy resin to add extra strength and durability to the finish. This method is best for outdoor wood or other items that need to withstand the elements.
Polyurethane is a synthetic that is a popular component of many commercial products, including paints, adhesives, foams, and varnishes. Polyurethane coatings are flexible and resilient and are used to protect a wide variety of surfaces.
Polyurethane is a super versatile material that has the ability to add strength and durability to any surface while still maintaining flexibility.
Polyurethane has a unique sealing ability that can be used to create a water-resistant surface or an oil-resistant surface. This makes polyurethane an ideal material for many applications, especially sealing outdoor wood.
Polyurethane is also resistant to extreme temperatures, abrasions and impacts, tearing, water, oil, and grease, and it exhibits good electrical insulating properties. It’s also resistant to mold, mildew, and fungus.
Some polyurethane is formulated to become UV-resistant as well, which is why it is a good option to finish epoxy. Since epoxy doesn’t have this ability, adding polyurethane over epoxy can enhance the strength of the material and protect it from the elements.
Polyurethane is a great clear finish that can be applied over epoxy. Applying a few coats of polyurethane over epoxy can add superior strength to the material and protect it from scratches and discoloration.
Since polyurethane is a strong chemical, it is highly recommended that you work in a well-ventilated area and wear proper protective equipment like a mask and gloves before getting started.
What you’ll need:
- Coarse sandpaper
- Fine-grit sandpaper
- Polyurethane (oil-based or water-based is fine)
- A brush or cloth to apply the polyurethane
- After your resin layer is completely cured, you should sand down the surface to make sure there are no bumps on the surface that can affect the final finish. Similar to the above method, you can use coarse sandpaper to go over large areas first, then go in with fine-grit sandpaper to smooth out the surface entirely. Wet sanding is recommended. After the surface is completely smooth, make sure to dry it thoroughly.
- Use a brush or a cloth to pick up the polyurethane. Brushes are more efficient with large, flat surfaces, but cloths are good to cover uneven designs. Cloths can usually apply the finish in thinner layers, so you will have to apply more coats to achieve the same finish. If you are using a brush, make sure to smooth out any brushstrokes and gaps when you apply the polyurethane.
- Alternatively, if you prepare a spray-on application, you can also buy polyurethane with a spray applicator. This option is very friendly to beginners and can help you get into intricate designs, but keep in mind that it can drip and look messy if you are not careful.
- Wait for the first coat to dry completely, which will take about 24 hours, depending on the polyurethane formula that you are using.
- After the first coat is dry completely, you can use fine-grit sandpaper to go over the area to smooth out any brush strokes or other uneven textures.
- After sanding, you can wipe the surface to dry it and remove any debris from the sanding.
- Repeat steps 2 and 3 to apply additional coats to your surface. Since oil-based polyurethane tends to be thicker, you will only need two or three coats, while water-based polyurethane requires four coats to achieve sufficient protection. The method of application can also affect how thick or thin the layers will be, so you can adjust accordingly.
- After the final coat of polyurethane is completely cured, you can use a polish to go over the entire surface, using circular motions to add shine to the finish.
Clear-Coat Alternatives To Polyurethane
If you are a little intimidated by polyurethane, there are a few other clear-coat alternatives to the polyurethane that you can use to finish epoxy using the same techniques.
Keep in mind that each of the alternatives below has different characteristics and offers different levels of protection, so you can choose one based on your preference.
Shellac is a natural alternative to polyurethane that has many of the desirable characteristics of polyurethane. It is naturally non-toxic and does not produce harmful fumes, which makes it less intimidating, especially for novices. It is quick-drying and easy to work with.
The finish can last for up to a year but will eventually need to be reapplied. Shellac is highly resistant to sunlight and does not turn yellowish or darken with age. This gives it an edge over other types of finishes, which tend to lose their luster over time.
Although it is most often used to enhance the natural finish of wood, shellac works well on almost every surface, including non-porous surfaces like metal or epoxy. If you want a clear coat finish that works just as well as polyurethane, this is definitely a great eco-friendly option.
Lacquer is a fast-drying clear finish made from resin and alcohol. It dries to a hard and durable finish that is impervious to water and other liquids and does not yellow or cloud as it ages. Lacquer has been used for thousands of years because it’s quite easy to find and finishes with a very smooth surface.
Lacquer has many advantages over other finishes, and it requires very little maintenance. Lacquerware can be treated with wax to enhance its appearance but otherwise requires no additional care and doesn’t need to be reapplied once every few years like other types of finishes.
Lacquer is considered a toxic material that can be hazardous to your health because the vapors are flammable and toxic when inhaled. It can also cause skin irritation and even blindness if it comes into contact with your eyes.
Application is a big problem with lacquer finishes because they are thicker than other clear finishes and have a tendency to run or droop in certain conditions. Professional sprayers use expensive heavy-duty equipment that can handle the viscosity of this liquid finish.
If you don’t want to invest in professional equipment and training, you can try using an airbrush instead of a spray gun, but this type of application still requires some skill and practice to master.
3. Tung Oil
Although many people believe that Tung Oil can only be applied over porous surfaces like wood, Tung oil can actually adhere to epoxy surfaces quite well. Since the oil won’t be able to soak into the porous surface, you will need to lightly sand the surface of the epoxy to allow the oil to grab onto it, and the oil will form a lovely clear finish over the epoxy.
Tung oil is both easy to apply and durable. In addition to its many other benefits, pure tung oil is food-safe, which means it is often used on kitchen cabinets and butcher block countertops.
Tung oil is especially friendly to beginners since it’s quite forgiving. You can just wipe the oil on the surface and clean up any residue. Since tung oil won’t be soaking into the epoxy, you only need one coat of oil to give the surface a lovely shine, and wipe away the residue.
Can You Paint Over Epoxy?
Since epoxy cures to become a hard plastic, you may think it’s difficult to paint over an epoxy surface. If you have a dull epoxy surface that cannot be polished, you may want to freshen it up with a coat of paint.
For the most part, epoxy coatings are impervious to paint, but it’s possible to change that. Sanding is the easiest way for you to prepare a surface for repainting. You can use coarse sandpaper to go over the epoxy surface to create a bit of texture for the paint to grab onto.
Then, you can go over the epoxy layer with a primer and a fresh coat of paint. Unfortunately, not all kinds of paint can successfully work with epoxy. Your best bet would be to use linear polyurethane paint (LPUs), which is specially formulated to work with epoxy.
LPUs usually have a glossy finish and will dry hard as epoxy does. Most LPUs are UV-resistant, so you don’t have to worry about discoloration. Similar to epoxy, LPUs can emit toxic fumes, so it’s best to work in a well-ventilated area with proper protective equipment.