Collection: Primaloc Epoxy Blog

A blurred photo of an epoxy batch being prepared, with a text overlay that says "The Role of Viscosity in Epoxy Resin"

The Role of Viscosity in Epoxy Resin

When prepping for an epoxy project, choosing the right type of resin is essential for achieving your goals. One key trait that distinguishes one epoxy resin from another is its viscosity rating, which can significantly impact the application process and the resulting outcome of your project.

For this article, we'll take a look at how viscosity affects epoxy resin, explaining the differences between our different Primaloc epoxy resins to help you make an informed decision based on your project needs.

Specifically, we'll examine how a low or high viscosity rating in an epoxy resin can affect its ability to blend or bond, as well as other relevant aspects.

How Viscosity Affects Epoxy Resin

Viscosity is a measurement of the "flow" of a liquid. This trait affect how smoothly and fluidly a liquid will typically move. For instance, a higher viscosity substance (e.g., molasses) will flow less smoothly and more slowly than one with a low viscosity rating (such as water).

Since epoxy starts off as a liquid, it also has a viscosity rating, which varies by resin type. This rating affects the epoxy in various ways.

Below, we'll discuss several aspects affected by viscosity, including:
  • Ease of Application
  • Air Bubble Release
  • Penetration and Sealing
  • Self-Leveling Properties
  • Curing Time
  • Final Finish

6 Aspects That Viscosity Affects

A batch of epoxy resin being poured onto a wooden substrate surface.

Aspect #1: Ease of Application

Thicker (more viscous) epoxy like our Primaloc Bar & Table Top Epoxy is less prone to dripping and running, making it easier to apply on vertical surfaces or edges without sagging.

On the other hand, thinner (less viscous) epoxy like our Primaloc Deep Pour Epoxy spreads more easily and is better for covering large, flat surfaces. This makes it excellent for certain types of epoxy projects, such as river tables and deep casting resin art.

Air bubbles being released from a thick layer of epoxy resin.

Aspect #2: Air Bubble Release

As some point in most epoxy projects, a flood coat layer is poured onto a substrate surface. It's during this time that air bubbles are likely to form within the resin finish. These can be fully removed from the finish if the epoxy used was handled properly.

For deep epoxy layers, a thicker resin is more likely to trap air bubbles because the viscous mixture makes it harder for the bubbles to rise to the surface and escape. In contrast, a thinner resin allows air bubbles to move to the surface and pop more readily, reducing the risk of bubbles in the cured epoxy.

As such, it's important to choose a low-viscosity resin for deep layers, so that fewer air bubbles are formed and those that do form are able to make their way to the surface for removal.

The typical method for removing air bubbles is to use a heat gun or blowtorch to force them to the surface and cause them to burst, releasing the trapped air into the atmostphere. However, for thicker epoxy resins, if a layer is too deep, the air may become unreachable by the heat gun, leaving it suspended within the resin finish.

So with that in mind:

When you need a strong, thin epoxy finish, choose Primaloc Bar & Table Top Epoxy.

When you need a deep epoxy finish, choose Primaloc Deep Pour Epoxy.

And if you need all of those things, use our Deep Pour for your thick layer, then apply a topcoat of the Table Top Epoxy for a highly protective final seal.

The epoxy seal coat application method being demonstrated with a brush.

Aspect #3: Penetration and Sealing

Higher viscosity epoxy is more suited to seal coat applications. Its tendency to stay in place allows the brushed-on seal coat layer to remain where it should long enough to seep into the porous substrate and bind with it, while also pushing out any air that may have been present.

For applying a seal coat, the ideal epoxy is our Primaloc Bar & Table Top Epoxy. To get the most out of deep pour epoxy projects, we recommend using the table top epoxy for both the seal coat and as a final super-protective topcoat.

Aspect #4: Self-Leveling Properties

Epoxy with lower viscosity tends to have less stringent self-leveling characteristics, quickly spreading out across a surface without much intervention. Meanwhile, an epoxy with higher viscosity will still self-level, but it may take longer and benefit from deliberate pouring to ensure it fully coats the surface.

Also relevant, though unrelated to viscosity, is the surface tension of an epoxy resin; this limits how thin an epoxy resin will spread before it levels out.

Generally, these are not major factors in determining the ideal resin for a project.

A  traditional clock hanging on a blue wall surface.

Aspect #5: Curing Time

The viscosity rating of any epoxy can influence its curing time; generally, thicker epoxy mixtures have a longer curing time than thinner ones. However, this can also depend on the specific formulation of the epoxy.

For most users, this is not an influential factor, as the difference in curing times is relatively minor with most projects.

Aspect #6: Final Finish

The viscosity can affect the final finish of the project. Thicker epoxy can result in a more substantial, potentially more protective coating, while thinner epoxy might produce a smoother, more glass-like finish.

Many other variables come into play here to determine the overall strength and clarity of an epoxy finish, however.

To achieve a truly optimal finish, do the following:
A side by side photo of our Primaloc Bar & Table Top Epoxy and our Primaloc Deep Pour Epoxy

Finding the Ideal Resin at Primaloc

At Primaloc, we specialize in premium variants of the two most common epoxy types for furniture and fixture projects. These are our Primaloc Bar & Table Top Epoxy and our Primaloc Deep Pour Epoxy.

Each of these resin types is suited to particular applications, with the Table Top Epoxy being the most popular for its use as a super strong sealant. Let's compare the two.

Primaloc Bar & Table Top Epoxy: High Viscosity, High Strength

Our Primaloc Bar & Table Top Epoxy is the standard choice for epoxy projects like bar tops, table tops, and countertops. These are some of the most common project types and rarely require a more niche resin product like Deep Pour Epoxy.

The benefits of using Table Top Epoxy over Deep Pour Epoxy include:
  • Unmatched Strength—This is the strongest type of clear resin available.
  • Seal Coat Suitable—You can use this to perform seal coating prior to your flood coat.
  • Consistent Self-Leveling—Our table top epoxy will self-level to 1/8 inch, every time.

In part due to high viscosity, these features allow the epoxy to be used for a project from start to finish. Additionally, the self-leveling property in particular makes this particular resin easy to recommend to beginners.

You can find our Primaloc Bar & Table Top Epoxy in our store.

Primaloc Deep Pour Epoxy: Low Viscosity for Thick Layers

Our Primaloc Deep Pour Epoxy is designed to be poured in thick layers of up to 2 inches at a time. This makes it exceptional as a casting resin—perfect for river tables and a variety of resin art projects.

This supported layer depth is made possible in part due to its low viscosity rating. Because it flows more easily, air is able to rise through the epoxy with less resistance, allowing it to escape even in thick resin layers.

We always recommend our Deep Pour Epoxy for projects needing thick layers, as it makes getting a crystal-clear cure much easier.

You can find our Primaloc Deep Pour Epoxy in our store.

A close-up view of a live edge wooden epoxy bar top.

Primaloc Epoxy: Premium Epoxy for Premium Results

With our premium Bar & Table Top Epoxy and our Deep Pour Epoxy, Primaloc gets the job done. Our epoxy resins are premium-grade, with high performance in every category, including:

  • Unmatched Strength: A Primaloc finish won't buckle, even under high pressure.
  • Long-Lasting Resilience: Primaloc epoxy lasts for many years with minimal care, and can endure high-traffic environments with ease.
  • A Crystal-Clear Coating: With its pristine, transparent appearance, looking at a cured Primaloc coating is like peering through a window.

Epoxy resin can be beautiful, strong, and long-lasting—which is why you shouldn't compromise on quality. With Primaloc Epoxy Resin, you get the ultimate finish in durability and visual appeal.

Protect your surfaces by giving them a rock-solid epoxy finish. Choose strong. Choose reliable. Choose Primaloc.


Previous Primaloc Answers: How Much Will 1 Gallon of Epoxy Cover?
Next The 3 Standard Coating Methods for Epoxy Resin