Flooring Finishes Part 2: Factory Finishes

March 02, 2018

As with most anything else, picking what type of finish you want on your factory-finished floor generally involves making some trade-offs. Let’s look at some of the advantages and disadvantages of the different finishes most commonly used at today’s wood flooring factories.

UV-CURED URETHANE

UV-cured urethane (or simply ‘UV urethane’) is the most common type of finish for factory-finished (‘prefinished’) wood flooring. The finish is applied to the wood at the factory and then hardened via a chemical reaction triggered by ultra violet (UV) light. Like other urethane finishes, UV urethanes protect the wood by creating an artificial barrier between the wood and the traffic above.

PROS
- Hard, durable, and stain resistant
- Barrier above wood helps protect against physical damage
- Requires no topcoat after installation

CONS
- Finish build looks like plastic - artificial
- Scratches generally show as white lines where the hard urethane has fractured - highly visible
- Refreshing requires sanding/abrading
- Can’t be feathered - repairs generally require board replacements or recoat of entire floor

A NOTE ABOUT ALUMINUM OXIDE: Aluminum oxide is one of several types of particles that are sometimes added to UV urethane finishes to make them more abrasion-resistant. Other additives that are commonly used include silica oxide (‘ceramic’ finishes) and titanium oxide. UV urethane finishes are sometimes mistakenly referred to as ‘aluminum oxide’ finishes. While many UV urethane finishes do contain aluminum oxide, many don’t.

When aluminum oxide and ceramic finishes were first introduced to the marketplace, these particles were often added to the topcoat to make the floor more scratch resistant. Over time, many manufacturers abandoned this strategy because they found that as the coating wore down, the additive particles would create micro-scratches in the finish that would give it a cloudy look. The abrasion resistance of the topcoat also made it more difficult to screen in preparation for a refresher coat. Now, most manufacturers who use aluminum oxide and other additives apply them in the sealer (base coat) to serve as a last defense against finish wear-through. So, the idea that additives like aluminum oxide make a finish more scratch resistant is usually not correct. They simply make it more wear-through resistant.

The enhanced wear-through resistance achieved by these additives is the main reason that manufacturers are now able to offer very long finish warranties of 35 and even 50 years. These warranties give the impression to consumers that the finish will perform and look better than other finishes. But to most consumers, the scratches are what bother them most, and the manufacturer with the long warranty could just be adding large amounts of aluminum oxide in the base coat of a low quality finish. Such a finish will get scratched up and need a recoat in five years, and the scratches aren’t covered under the product’s meaningless 50 year warranty.

Some manufacturers, particularly in Europe, prefer to leave additives like aluminum oxide out of their finishes for two reasons. First, they affect clarity, creating a hazy look, and second, they make it more difficult to refresh the finish with a topcoat. At Monarch Plank, we agree with the Europeans. We believe that the added wear-through resistance provided by these additives isn’t worth sacrificing beauty and repairability, since most people refinish their floors due to scratches long before the finish comes close to wearing through. We choose instead to use quality top-coats that give maximum scratch resistance and total finish clarity.

One common myth about UV urethane finishes, and urethanes in general, is that they are water-proof and will not be stained by liquids left on the floor. In fact, if you look at urethane finishes under a microscope, you can see thousands of tiny pores. Water vapor can slowly pass through these pores, and, given enough time, chemicals left on the surface of the floor (including coffee, wine, pet urine, etc.) will make their way down through these pores and discolor both the finish and the wood beneath. It is true that urethanes are generally more stain resistant than oil finishes, but it’s not true that they are immune to such damage.

PENETRATING OIL

Sometimes referred to as ‘traditional’ oils or ‘natural’ oils, penetrating oil finishes generally contain a natural oil base, such as linseed, that is mixed with solvents to accelerate drying. Tung oil is a well-known example of a penetrating oil finish. Penetrating oils absorb into the wood and usually require the application of at least two coats. Penetrating oil finishes are referred to as ‘oxidative’ oils, because they dry by exposure to the air, as opposed to UV-cured oils, which only dry with exposure to UV light.

Penetrating oil finishes are very popular in Europe, where there is a long tradition of oiled flooring and most homeowners understand what it takes to nourish and maintain them. But they do require regular maintenance, or the floor will lose its seal and become very prone to staining and water-spotting.

PROS

Natural look and feel - soaks into the fibers rather than covering them with plastic
Easier to repair – new oil can be feathered into the surrounding finish
Can be refreshed without sanding

CONS

Usually requires a topcoat of oil after installation
Requires frequent maintenance with proper products – finish needs nourishment
Less stain resistant than urethane or UV oil
Wood is more exposed to physical damage

HARDWAX OIL

Hardwax oils are another type of ‘oxidative’ (air-dried) oil. Hardwax oil finishes are like penetrating oil finishes in that they contain some natural oil such as linseed or soy that is mixed with a solvent to accelerate drying. Hardwax oils are different from penetrating oils, however, in that they also contain wax, usually a mixture of paraffin with carnauba and/or beeswax. When hardwax oils are applied, the oil soaks into the wood and separates from the wax, which is left at the surface. This wax layer is then buffed in to give the wood an attractive, silky luster. The wax also helps to seal the floor.

Most hardwax oils on the market require the application of at least two coats, but there are some ‘single-coat’ hardwax oils that make use of isocyanate hardeners to bond quickly to the wood fiber and create a seal with just one thin application. These single-coat hardwax oil finishes have unique characteristics that require that they be maintained with different types of soaps and cleaners than most oil finishes.

The advantages and disadvantages of hardwax oil finishes are more or less the same as penetrating oil finishes:

PROS

Natural look and feel - soaks into the fibers rather than covering them with plastic
Easier to repair – new hardwax oil can be buffed into the surrounding finish
Can be refreshed without sanding

CONS

May require a topcoat of oil after installation
Requires regular maintenance with proper products
Less stain resistant than urethane or UV oil
Wood is more exposed to physical damage

UV-CURED OIL

Like other oil finishes, UV oils are intended to protect the wood from within by sealing the fibers, rather than creating a barrier between the wood and the traffic above, as urethanes do. However, almost all UV oils contain some percentage of acrylic, the main component in urethane finishes, which is why UV oils are often viewed as hybrids between urethanes and oils. The higher the acrylic content of a UV oil, the more it will perform like a urethane, with all of the associated pros and cons. Higher acrylic content lends better stain resistance and protects the wood fibers better from physical damage, but also creates more of the plastic looking build above the wood, is more challenging to repair, and may show white in the scratches like a urethane. Like UV urethanes, UV oils are cured at the factory via a chemical reaction triggered by UV light.

PROS

Can be nourished and refreshed without sanding, like other oils
Natural look and feel
Requires no topcoat after installation
Better stain resistance than penetrating or hardwax oils
Better initial durability than penetrating or hardwax oils – longer time before first re-oiling is needed

CONS

Can be more difficult to blend/repair than other oils
Less stain resistant than urethane
Requires regular maintenance with proper cleaning products

SO WHICH FINISH IS BEST?

At Monarch Plank, we believe that each of these types of finishes has its advantages, and that the right choice depends on personal preferences. Some people want their wood floor to look as natural as possible, look forward to the floor taking on a patina from daily use, and like the idea that they can repair or refresh their floor with a little bit of work on a Saturday afternoon. For them, a Penetrating Oil or Hardwax Oil finish might be a good choice. Others might enjoy the natural look and feel of an oil finish, but prefer a little bit more durability, stain resistance, and easier initial maintenance. For them, a UV Oil may be the better choice. Still others want a floor they can install and forget about, requiring as little maintenance as possible until it’s time to replace or refinish the floor completely. Or the floor might be going into a location where the occupants can’t be trusted to use the specialty care products required for oil finishes. In these cases, UV Urethane is probably the better choice.

We have manufactured and sold floors with all three of these families of finishes, but our current product line emphasizes UV Oil and UV Urethane options. With our ultra low-gloss, low build urethanes and UV Oils, we can provide the look and feel of the most natural finish without sacrificing stain resistance and durability. Penetrating Oil and Hardwax Oil finishes definitely have their place, but we have found that the amount of education and care that those finishes require can create challenges. In the U.S., most people are accustomed to urethane-finished floors and therefore have expectations about the initial durability and stain-resistance of the finish that are hard to meet with Penetrating Oils and Hardwax Oils.