Polyaspartic vs Epoxy: Which is better and why?

You can find all kinds of disinformation on floor coatings for garages. One area where incorrect information abounds is people contrasting epoxy vs. polyaspartic coatings. The person going on a rant is often not really discussing the coatings in the proper contexts of how they are being used and why.

Just to be clear, we are coming to this article with 20 years in the garage floor coatings business - with two locations and over eight thousand customers.  We have worked with many different manufacturers of coatings and formerly was head of an advisory committee for a national franchisor (specifically for the garage floor coatings).

Epoxy vs Polyaspartic: Which is better?

The short answer is both. It depends upon what they are being used for.  

Before we get into the specifics, we want to address statements thrown around such as “polyaspartic is 4x stronger than epoxy”, which has no direct meaning.  

Stronger in what way? Stronger smelling? Most definitely. Stronger bond to the concrete in real world conditions, unlikely.   What matters in coatings has everything to do with the usage and required results.   For a typical garage floor coating, the requirements are:

• no hot tire peel (no disbonding from the concrete)
• chemically resistant (able to tolerate gasoline, oil and other common chemicals)
• scratch resistant (able to hold up to wheeled and foot traffic, along with items dragged across the surface)
• UV resistant (not yellowing or color shifting from sunlight or other strong light exposure)

Topcoat – the final coating layer of a chemical system providing the direct wear layer

When it comes to the topcoat (final layer of the chemical system), a polyaspartic is almost always the best choice for a typical, residential garage floor. It will provide better chemical resistance, UV resistance and scratch resistance than epoxy.   A high quality polyaspartic will normally be water clear or close to it – and stay that way. Whereas a clear, UV resistant epoxy coating will ultimately color shift to a more amber tone directly depending upon its exposure to sunlight or strong UV lights, plus be easier to scratch.

• We point out “typical” residential garage, because if it’s a commercial garage being exposed to BrakeClean and other harsh solvents, a high chemical resistant urethane (CRU) will normally outperform any polyaspartic.

Funny thing most don’t realize is that the epoxy is easier to scratch because it’s more rigid (harder). It doesn’t have as much “give” as the polyaspartic.

NOTE: All the benefits of a polyaspartic topcoat can be negated by coatings companies who jam all the activities (surface prep, crack repair, base coat with chips and top coat) into one day installations.   Now, the final layer is being applied late in the day by installers who are tired, slowing down and ready to go home.   Polyaspartics require installers to move at a brisk pace, practice good timing of their batch mixes and pay great attention to their rolling out of the materials.

One day floor installations are subject to basecoat issues too – keep reading to learn more.

Basecoat – the bonding layer to the concrete floor

Here is where we’ll get kickback from some that a high-quality epoxy makes a better base layer than a polyaspartic (polyurea or polyurethane).

First, epoxies begin to solidify slower than polyaspartics which allows greater time in a liquid, viscous state to soak into the pores and scratch patterns in the concrete. This is called “wetting out” the surface. Penetrating the pores of the concrete substrate and creating mechanical & chemical bonds to the concrete are critical. Self-priming epoxies (by their slower nature and flow agents) do a better job of mechanical bonding to create an anchor-like effect, plus they chemically bond by a cross-linking reaction between the epoxy resin and the concrete itself.

Second, with a polyaspartic coating, warm temperatures, and humidity both accelerate the hardening process, which only decreases the time the polyaspartic has available to “wet out” the prepared concrete. Two-part, thermosetting epoxies are not impacted by humidity.

Third, add in the poor surface preparation practices of many outfits, the chance of peeling (or delamination) just increases even more. Too many outfits don’t use heavy enough equipment and/or aggressive enough diamond tooling under their grinders.   We have seen outfits using 80 or higher grit diamonds that do not leave the proper concrete surface profile (CSP). They should be using a 40, 25 or 16 grit diamond tooling.

Last, many people installing all polyaspartic garage floor coatings are applying a primer, then following up with another polyaspartic layer where they add the chips.   This practice has all the prior 3 issues, but then adds the probability that the two layers will later separate (due to poor inter-coat adhesion – i.e. the two materials did not chemically bond together).

We know some manufacturers will take great umbrage at the paragraphs above and throw numbers at us from their lab testing.   But those lab tests are always done in ideal conditions for a polyaspartic (72 degrees or lower, 50% or lower humidity, perfectly prepped concrete sample with medium hardness).   Try using the same materials in the field with warmer temps, higher humidity, wind blowing and an extremely hard, concrete slab that has warmed up throughout the day – and you get very different results.  

Performance in the field is the only real result that matters.

At the end of the day (or blog post) it's not really epoxy vs polyaspartic.  The best solution is using each in the proper layer of the garage floor coatings system.