The coating on your hardwood floors protects the wood and brings out its natural beauty. But not all wood floor coatings are alike. Some are more durable than others, and they all have different qualities that affect how your floors look. But most contractors don’t talk a whole lot about the coatings they use on wood floors, and most homeowners don’t think to ask.
Different contractors use different types of coatings, and they apply them differently—and sometimes incorrectly. Many put down three coats. At Lifetime Hardwood Floors, we do up to five, because five coats offer the best protection, and we don’t call ourselves “Lifetime” for nothing.
For the first two coats, we use a water-based sealer that soaks into the wood to protect it from the inside out against moisture and other damage. Up to three layers of a high quality topcoat go down on top of the sealer. The topmost coat is the sacrificial coat that gets scratched and scuffed through everyday use. Once these topcoats wear away in heavy-traffic areas, the entire floor has to be sanded down and refinished. (That’s why re-coating your floor periodically is so important—it replenishes those protective topcoats and resets the refinishing clock.)
Some contractors use the wood sealer for the topcoat, which is a terrible choice, since sealer offers zero UV protection and no scuff-resistance. But it’s cheap, and the homeowner doesn’t know the difference until they notice their floor looks like heck after a few months and needs to be completely refinished three years later.
So, what coating should your contractor use? Well, it’s largely a matter of preference, so knowing the pros and cons of different coatings—and what to stay away from—can help you choose. Without further ado, we break down the five most common wood floor coatings and discuss VOCs, curing times, and durability for each one so that you can make the best choices for your floors and the way your family lives on them.
Air-Cured Wood Floor Coatings
Air-cured coatings are those that harden (cure) when they’re exposed to air. Polyurethane—the most commonly used wood floor coating—is essentially a liquid plastic that hardens into a protective coat. Polyurethane coatings for wood floors are either oil-based or water-based.
Once upon a time, oil-based polyurethane was the standard coating for a wood floor. Oil-based polyurethane has an amber tint, giving old wood floors their warm, yellowish/reddish glow, which deepens over time. Depending on the wood species and your aesthetic bent, this coloring can either enhance the floor or completely ruin its look.
VOCs: Oil-based polyurethane has very high VOC levels, at 500 grams per liter. Exposure to these toxic gases can cause or worsen respiratory problems like asthma or COPD as well as cause headaches and dizziness, which is why wearing a respirator during application is required. Oil-based polyurethane can off-gas VOCs for a couple of months or longer after it’s applied. If your floors are being coated with oil-based poly, you’ll need to move out of your house for at least three days—longer if the kids are very young—or until the application is complete. Once you move back in, you’ll want to keep your windows open and fans running until the odor begins to dissipate.
Curing time: Oil-based polyurethane fully cures in 30 days—until then, it’s susceptible to scratches and scuffs. Oil-based polyurethane must dry for a whole day between coats, so it can take three to five days to finish the floor. You can walk on the floor after 48 hours and replace furniture after four days. You’ll need to keep the dogs off the floor for two weeks, and wait the full 30 days before you put rugs down.
Durability: Oil-based polyurethane is fairly durable, lasting around 10 years before it needs refinishing due to the coating wearing away. However, re-coating every three to five years preserves the look of the floor and protects the wood underneath. Re-coating an oil-based topcoat is rather inconvenient though, since you have to vacate your home again and put in the waiting time for furniture, dogs, and rugs.
Water-based, or waterborne, polyurethane goes on clear and stays clear. There are two-part and one-part water-based coating systems. Two-part waterborne polyurethane consists of the polyurethane and a catalyst. The more catalyst in a two-part coating, the stronger and more durable the coating, and the better the UV protection and scuff-resistance. A one-part coating is just polyurethane. Avoid one-part wood floor coatings at all costs, because they’re softer than oil-based polyurethanes, provide no UV protection, and your floors will need refinishing in three to five years.
VOCs: Water-based polyurethane is certified low-VOC at around 275 grams per liter, although adding the catalyst does increase that number somewhat. But you don’t need to wear a respirator while applying it, and while there is some odor associated with water-based polyurethane, it’s considerably less intense than oil-based odors and dissipates in a few days. As long as you can avoid walking on the floor for 24 hours after coating, there’s no need to move out of your home during application.
Curing time: Water-based polyurethane fully cures in seven days. It only needs to dry for a couple hours between coats, so a floor can be coated in just a day. You can walk on the floor 24 hours after application. After three days, it’s 90 percent cured, and you can (carefully) move your furniture back into the room, although you need to wait the full seven days before you put rugs back down or let the dogs back into the room.
Durability: Two-part water-based polyurethane is very durable, protecting your floor from scratches and water damage. Without periodic re-coating, a two-part water-based coating will last for 10 to 15 years or longer, depending on the amount of catalyst that’s added to the polyurethane. As always, re-coating can extend that lifespan indefinitely.
Light-Cured Wood Floor Coatings
Until recently, light curing wasn’t even a thing in the hardwood flooring industry, although it’s long been used in other industries, like dentistry and automotive coatings. Whereas air-cured wood floor coatings like polyurethanes cure when they’re exposed to air, light-cured coatings cure when they’re exposed to UV or LED light.
UV coatings cure via a photochemical process. These water-based products contain a combination of ingredients whose molecules bond instantly when hit with ultraviolet light, forming a hard, durable coating.
VOCs: UV coatings have extremely low VOC levels—just 30 to 50 grams per liter. You may notice a very slight odor for a few hours after curing, but by the next day, it should be gone.
Curing time: UV coatings cure instantly. You can walk on them, replace furniture, and let the dogs loose as soon as the UV light hits the surface.
Durability: UV wood floor coatings are extremely durable. One great benefit of UV coatings is that they can be spot-coated, which means that if something damages the floor, you can have just that spot re-coated without having to do the whole floor. This makes it extra ideal for gyms, restaurants, and retail, which see heavy traffic in some areas but not others.
LED coatings cure instantly when they’re exposed to LED light. LED coatings are hardwax oils, which are a blend of natural waxes and oils that penetrate deeply into the wood—rather than sit on top like other coatings—to offer superior protection against moisture and stains as well as project a warm, natural matte look.
VOCs: LED coatings contain zero solvents and zero VOCs.
Curing time: LED hardwax oils cure as soon as they’re hit with LED lights, which means you can move right back in like nothing happened.
Durability: LED-cured floors are protected from above and from within. The hardwax oils that permeate the wood actually harden the wood from the inside out, making them exceptionally durable.
Aluminum Oxide Wood Floor Coatings
Aluminum oxide coatings are the hardest wood floor coatings in the industry. They’re generally applied at the factory, and pre-finished wood floors coated with aluminum oxide are the most durable of all. But when they do need a re-coat someday down the road, they require chemical etching to ensure the new coating will adhere. Pre-finished floors typically have a thinner wood profile, which means that they probably only have one refinishing in them before the entire floor needs replacing.
Lifetime Hardwood Floors can add an aluminum oxide additive to water-based polyurethane and UV-cured coatings. Doing so adds to the VOC level, but it also increases the strength of the coating by around 40 percent, which makes it ideal for floors that need a little extra protection against heavy wear (we’re looking at you, Fido.) Only the topmost coat contains the additive, and when it’s time for a re-coat, the floor will need to be chemically etched to ensure the new coat will adhere properly.
Bottom Line? Quality Matters
No matter what type of coating is used on your wood floor, low-quality products won’t perform up to your standards, unless your standards are very low. Unfortunately, some contractors save money by cutting corners and using cheap coatings that don’t look as good, adhere as strongly, or stand up to traffic as well as higher-quality products. Cheap coatings need to be re-coated more often than quality coatings, too, and that right there negates any savings a homeowner might enjoy by going with the lowest estimate.
At Lifetime Hardwood Floors, we always use the highest-quality coatings in the industry. For water-based polyurethane coatings, we use Bona Traffic HD, which has three times the catalyst as other waterborne coatings and lasts a lot longer. For UV coatings, we use ProCoat, the pioneers of UV curing for wood floors. For LED finishing, we use Vesting products, which are the best in the business.
If you’re in the market for a new floor, a refinish, or a re-coat, contact us at Lifetime Hardwood Floors today. We’ll discuss your coating options and provide you with a beautiful, durable floor that will last a lifetime.