yellow of epoxy flooring garage floor coating

Yellowing of Epoxy Coatings

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In this blog, we’re responding to a great question posed by one of our potential customers pertaining to the yellowing of epoxy coatings. Yellowing may occur for several reasons, but in this case, our prospect was referring to the yellowing that occurs at points where the tires of a parked car rest on a coated garage floor.

A Quick Sidebar

On our website,, we invite our customer prospects to ask us any question pertaining to epoxy, polyurethane and polyurea-polyaspartic coatings in general…or any question pertaining to their specific coating project. On the same website, we provide our potential customers with a “10 Important Questions” slick to help them ask the right questions (with answers) when obtaining bids from any floor coating company.

Why is this Important?

Because when seeking bids from multiple contractors, asking the right questions is critical to ensuring you hire a professional floor coating company. There are hundreds of contractors that install epoxy, ployureathane and polyurea-polyaspartic floor coatings…many are suspect. They’ll use low-grade products, or poorly prepare the concrete, or simply lack knowledge or technique. The only way to flush out a disreputable contractor is to ask questions and know what the answers should be.

Click the link to read our “10 Important Question’s” (and answers) slick.

Back to Our Customer’s Question

Our customer posed this question. The question refers to a top coat applied to his neighbor’s garage floor that is “yellowing” where the car tires rest on the top coat.

I am looking for an epoxy floor for my garage and shop. My neighbor had his garage floor done a year ago with a 100% solids epoxy with the decorative flakes and they used a two part urethane top coat.

The floor looked fantastic but now the top coat is showing yellowing stains where the tires from the car sit on it. This stopped me from moving forward with my floor until I can get an answer. I do NOT want my floor showing yellow stains from tires and your post says it is from urethane top coats??? So what top coat do you use that does not yellow and do you warranty it from staining?? 

Thank you, 


Why does yellowing occur?

Tire marking or “hot tire pickup” on concrete coatings is caused by a phenomenon called “plasticizer migration”. The rubber used to make high-quality car tires contains plasticizers to make the tire softer and improve traction. When the car is driven, the tires heat up, causing the plasticizers to soften and leach out of the rubber.

When a hot tire is parked on concrete sealed with a polyurethane topcoat, the plasticizers migrate into and discolor the topcoat. Why? Because polyurethanes contain plasticizers too! As like attracts like, the plasticizers leach into the polyurethane coat and produce the unsightly yellowing. So the yellowing of the epoxy coating is actually the yellowing of the polyurethane topcoat!

How do you prevent it?  

Simple. Never use a polyurethane as a topcoat in a garageever (or as a topcoat for your driveway if that’s where you intend to park your car). Although polyurethanes, like’s Poly Pro, are great topcoats for low-odor interior installations or exterior patios…but they aren’t where vehicles are parked for extended periods.

Instead, use a polyaspartic as the topcoat in garages (like’s Poly Hybrid). Polyaspartics have high solids content and extreme chemical & UV resistance…and don’t “amber” when exposed to car tire plasticizers.

The Wrap

In the business of floor coatings, knowledge is key. Want to avoid the yellowing of epoxy coatings? Hire a professional floor coating company.

How? Use our “10 Important Questions” slick to help you make the right choice.

About the Author
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Robert Hanson is the President and founder of (GFC), an ISO 9001-certified company that has specialized in the installation of epoxy, polyurethane and polyurea-polyaspartic flooring for over 25 years. Robert’s evolving knowledge and experience pertaining to concrete coatings and installation techniques culminated in GFC’s impressive line of commercial-grade Eco-Corflex floor coating products, flake epoxy flooring blends and unique coating systems. His proprietary floor coating products and flake blends are sold to over 35 franchisees & authorized dealers across the United States.

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