If you're new to epoxy resin, you're probably unfamiliar with the different terms frequently used when describing the coating steps of the epoxy crafting process.
For this article we'll be explaining three different types of epoxy coating, each of which serves a unique purpose. These are:
- Epoxy seal coats
- Epoxy flood coats
- Deep pour epoxy coats
Two of these are present in nearly every epoxy project, while the third is only used for specific types.
Let's get started.
The three types of epoxy coating
Epoxy seal coating
An epoxy seal coat is applied as a preliminary step; for non-marine purposes, it's always made using the table top epoxy, never the deep pour epoxy. It's one of the first things you do as you start working on your project.
In epoxy crafting, the material you'll be applying the epoxy to is called the substrate. This is the material that your epoxy resin mixture will be bonding to during a chemical process called curing.
Most of the materials that epoxy bonds best to are porous, notably all types of wood. This means they have tiny, often imperceivable holes and grooves throughout their makeup, and these holes generally contain air (unless they've been filled with something else).
When you pour epoxy onto a surface like this, the epoxy will slowly seep into the material, attempting to fill these little voids until there's nowhere left to go, then it will settle on the surface itself.
Normally, when you pour a liquid (such as water) onto a surface like this, it doesn't take but a moment for it to seep in and drench it, but epoxy happens to be very viscous, so it flows slowly by comparison and takes a lot longer to settle in the same situation. It's also thicker, so air and vapor don't pass through it as easily.
Because of these two characteristics, when epoxy is poured directly onto a porous surface, what will often happen is the air trapped within will attempt to make way and escape as the epoxy settles in, but because of how thick and viscous the epoxy is, the air instead only partly escapes, ultimately becoming trapped in the epoxy resin itself. These instances are referred to as air bubbles.
To avoid this concern, we always recommend applying an epoxy seal coat. This type of coating is one you paint onto the surface using a nice, clean paintbrush. The idea is that by mixing up a small batch of epoxy and manually painting a thin layer of it on the surface prior to any of your proper poured coat, you'll be able to release the air and seal the pores of the surface, preventing the formation of many air bubbles.
The thin layer will be thick enough to seep in and seal the substrate, yet thin enough to allow the air that does make it through to escape. You'll be pouring a flood coat later, and the brush strokes will vanish as the seal coat blends with the flood coat, as long as you time it right per the instructions.
In some scenarios, you may even want two seal coats. This isn't especially common but can be necessary when you have a very porous surface, if you're embedding certain types of objects, or if you're simply uncertain whether the first coat was applied fully.
Next, we'll describe flood coating.
Epoxy flood coating
An epoxy flood coat is your final epoxy coating. This is what you pour onto your surface sometime after your seal coat(s), and it is the most visible and appealing part of the project. It's also one of the easiest parts.
For epoxy flood coating, much like with seal coating, you'll always use the table top epoxy. This is because table top epoxy is the most resilient and thickest epoxy type.
Additionally, it happens to be self-leveling. It has higher viscosity than other epoxy types as well as high cohesion, so it tends to stick to itself well, much like how water will bead up on non-absorbent surfaces.
This self-leveling aspect is what makes the flood coating step so straightforward. You simply mix up your batch, often using a power drill with a mixing bit, though if you're making a batch of less than a gallon, you'll want to manually mix with stir sticks.
Once you've mixed according to the included instructions, you'll immediately pour the flood coat batch directly onto your surface, moving slowly about to make sure it all gets covered. It will self-level until your coat has reached a uniform 1/8 of an inch, at which point any excess will flow off the table and partially under the substrate.
If you happen to mix and pour too much, it may start to drip onto the floor, so it's a good idea for your project to have something like 4 mil painters plastic on the surface beneath to catch these droplets.
For flood coats, one is usually enough, especially for common projects like epoxy countertops and bar tops, as well as table tops. However, since the coat can only be poured in 1/8 inch layers, some users choose to apply a second one sometime after to make the epoxy thicker as desired. Make sure you follow the instructions for this if you decide to apply a second flood coat.
And now we come to the third type of coating: deep pour epoxy coating.
Deep pour epoxy coating
A deep pour epoxy coating is made using deep pour epoxy. It has a thinner consistency when mixed and is less likely to retain air bubbles or develop other blemishes related to layer thickness.
Because of this, our deep pour epoxy can be poured in one inch layers without issue, though you'll always want to block off the perimeter because this epoxy will flow right off the surface and onto the space beneath it due to its lower viscosity.
Deep pour epoxy coats are what make the "river" in epoxy river tables. They're also used for casting due to the thick layer depth you can fill in with each pour. There are other uses, too. Generally, just filling in deep voids and gaps between unusual substrates are what deep pour epoxy excels at.
However, deep pour epoxy does have a downside: it's not as durable as the table top epoxy. For any project that will see traffic or regular interaction, you'll always want to apply a flood coat of table top epoxy. This is called a topcoat, and it will protect the deep pour epoxy layer(s) and preserve your project for years to come.
You can learn more about the combination of deep pour coats and flood topcoats here.
Have questions? Contact us for answers and advice!
Starting your first epoxy project can seem daunting. There's a lot of terms and steps to learn when it's your first time, but it's worth it when you see the end result.
If you have questions, need planning advice, or just want help ordering the correct supplies and materials, reach out to us at UltraClear Epoxy.
You can speak with one of our experts via phone or email here, or you can text-chat directly online by clicking the help button at the bottom right of your screen.