Repair & Care
Oil Based Flooring Finishes. Basic Knowledge
When I was first invited to write this article on oil/solvent-based floor finishes, my first thought was not to come across to the homeowner or professional as making some “absolute” statements or impressions of oil-based finishes. The only way I knew to avoid this was by comparing oil-based with another well known and fast, upcoming hardwood floor finish better known as water-borne or water-based finishes.
I will mention that the oil or solvent based finishes here discussed will be the oil-based polyurethane (sometimes called oil-modified poly or OMU). The reason I clarify this is because there are other solvent based floor finishes that have certainly earned a place of honor in the floor refinishing trade.Old Smelly Finishes Are Disappearing
Solvent type finishes are being slowly eliminated because of health issues, changing environmental laws, and a general offensiveness to the senses. Examples of these finishes are: acid cure and moisture cure floor finishes. And as you understand more about polyurethane finishes, hopefully you'll agree that there are better options for the homeowner and professional alike.
To begin, the purpose of any floor finish should be to enhance the beauty of the wood and protect it from outside elements. All polyurethane, whether oil or water-based, are a film-building finish. Contrary to popular belief, polyurethane does not penetrate into the wood. It's a surface-build protection. And in laymen's terms, polyurethane is plastic.
Doesn't Cure Quickly
Looking specifically first at oil-based polyurethane. It was always interesting to learn, this type of finish has been around in the United States since about 1936 when Fabulon Co. first started making it for bowling allies. Today, their OMU is still known for it's capabilities of flowing out to a smooth and durable finish. These are the same qualities that most reputable companies have strived to attain as well. A coat of this kind of poly can dry and be recoated in approximately 12 hours.
Humidity and temperature can slightly change this 12 hour period. This type of finish will take 3-7 days to cure hard enough before furniture can be placed back onto the floor. Unfortunately, the smell of oil-based poly will linger for several days or even weeks. This has been one objection to people who suffer from allergies and sensitivities.
Oil-based poly has a way of filling in and flowing over the open grain of many hardwoods. This gives a desirable "grain-filled" characteristic. And it will develop into an amber (brownish-orange) look as it ages over the next several months. The amber look is a nice addition to this type of polyurethane especially if you want a warm tinted look.
Oil-based poly will always have a place in the hardwood floor industry, but with the trendy changes in law we can expect that newer, more competitive finishes will emerge.
Sealers & Finishes - Differences Explained
What is a sealer and what is a finish? While some good polyurethanes can do double-duty as a sealer and finish, I can appreciate the roles that each product plays and the unique properties they need to maximize their effectiveness.
Let’s begin with the end in mind: the finish. A finish is the final coating applied to the floor that will be exposed to traffic and wear. In other words, this is what you’ll be walking on.
Properties Associated With a Superior Finish Coating
• For the contractor, you want it to flow well for an even coat without brush or roller marks
• Cure quickly so the floor can be returned to use
• Produce an even sheen across the floor
• Resist abrasion and erosion from traffic
• Provide adequate chemical resistance against spills from wine, food, and cleaning solution
The properties that make a good finish, don’t necessarily need to be in your sealer and this is why I often turn to a system instead of just one product for sealing and finishing.
Good Sealer Qualities
• Penetrate into the floor to fortify the wood
• Block any potential issues with tannins (see tannin details)
• Sand easily and build evenly in preparation for the finish
• Dry crystal clear with no applicator marks or heavy spots
• Dry fast with an open recoat window for multiple coats in a day without abrading
As you can see, the best features of a sealer are unique when compared to those of a finish and vice versa. Compare this to the one-size-fits-all approach of other products and you can see why this might be smarter and deliver superior results.
What are tannins? Tannins are naturally occurring, water soluble compounds found in wood. Their presence or concentration can’t be predicted because they cannot be detected visually until it’s too late. Tannins can potentially migrate to the surface of a wood floor when using a water-based sealer, resulting in discoloration or bleed.
Most people describe tannin bleed as looking like a coffee stain under the sealer. Tannin bleeding will produce an undesirable discoloration in the wood which will require resanding the area to remove it completely. Tannins are not damaging to wood and won’t degrade the quality or performance of the coating.