A Clearer View of Floor Finishes
Once you understand the pros and cons of traditional methods and modern products, it's easier to balance history and practicality.
Fanciers of old houses are attracted to the many hand-crafted features that give these buildings their character, and handsome wood floors certainly top the list. Even moderately old houses are likely to have floors that show higher quality installation and materials than more recent houses. Unfortunately, floors are also subject to heavy use so finding a clear finish that is adaptable enough to be repaired yet strong enough to protect the wood from stains and wearÑwhile having the right period lookÑcan be a challenge.
Every finish has its pros and cons, and no one finish is best for every floor type. If you are restoring an existing wood floor or adding a new one, knowing what the finish options are will help guide you to a floor that is compatible with your old houseÕs appearance and practical for your lifestyle.
The Background on Finishes
Before looking at the products on the market, itÕs useful to understand what finishes might have been on your floors in the past. The earliest wood floorsÑusually softwoods such as pineÑwere often never finished. In the North, tight-grained, old-growth Eastern white pine is still going strong in many homes. Often referred to as Òpumpkin pineÓ because it has aged to a warm, amber color, this wide-board, flat-sawn flooring was left natural and maintained by regular washing with water and homemade lye. Later on, these floors may have been finished with linseed oil or hand-rubbed with wax for color and protection. In the South, flooring was often made from dense, resinous heart pine and left equally bare. Whatever the species, lesser grade wood was commonly used on floors in less important rooms, particularly above the first floor, and usually painted. From the colonial to the early Victorian era, homeowners also enjoyed decorative floors produced by stencilling borders or painting faux mosaics and rugs.
As manufacturing and railroads made paints and coatings more available after 1860, varnish, shellac, and other clear, hard finishes became popular for woodwork. Homeowners enjoyed both the shiny presentation of varnish and the protection it offered for the increasingly popular hardwood floorsÑparticularly oak, which develops a deep, blue stain upon contact with water. Varnish was a product of natural oils and resins until the 1910s when the first man-made resins appeared. The 1960s brought a new generation of tough, synthetic resins and the first wave of exceptionally strong (albeit then plastic-looking) polyurethane varnishes and Swedish finishes.
Finishes by Type
From a technical perspective, floor finishes can be divided into two general types: those that sit on the woodÕs surface and those that penetrate the wood. Surface finishes protect the floor by laying on the surface and creating a barrier between wood and the environment. When you touch the floor you are really touching the finish. As wear occurs on the floor, the finish, not the wood, is worn away. These types of finishes include shellac and varnish, and more modern coatings such as Swedish finishes and polyurethanes. Paint, of course, would also be in this category, along with lacquer (furniture finish) and wax.
Surface finishes are basically combinations of resins and solvents. The solvents, which allow the resins to be fluid, evaporate once the finish is applied and leave the resin to set up a film on the wood. Shellac and lacquer work this way. Tougher finishes, such as traditional varnishes and polyurethane coatings, go through a second stage called polymerization or cross-linking: The resin molecules react with oxygen and bond to form a film that cannot be redissolved by the original solvent. Traditional varnishes and polyurethane coatings will also include some proportion of oil that makes them harder or softer. Marine spar varnish is a long-oil (high oil content) varnish so it is flexible enough to move with wood that is outdoors. Interior floor and woodwork varnishes are typically medium- to short-oil varnishes because hardness is generally more important than flexibility.
HereÕs what these distinctions can mean when it comes to finishing wood floors. Clear surface finishes tend to have a yellow or amber hue (the resins) that will darken the woodÕs appearance and deepen over time. They also have sheen that varies from high gloss (popular for 150 years) to subtler, satin effects (a more recent option produced with additives). Most modern surface finishes set up relatively quickly, and the floor can be used much sooner than it could with their penetrating counterparts. In addition, they form a hard surface that makes cleaning easier but maintenance and repair difficult. Some finishes seem indestructible, but they readily show scratches and arenÕt flexible enough to make good candidates for, say, a softwood floor in wide boards. Polyurethane in particular is durable but difficult to repair without refinishing the entire floor.
In contrast, penetrating finishes sink into the wood so when you touch the floor surface you are actually touching wood. These types of finishes include linseed oil, tung oil, and various specialty oils such as lemon, walnut, soy, and Danish oil (a mixture of oil and varnish). Linseed oil (pressed from flax seeds) is a drying oil that has been used for centuries to coat wood and stone and, with pigments, make paint. Tung oil (pressed from nuts of the Chinese tung tree) is another drying oil that came to North America about a century ago.
Though tung oil has historically been used mostly for furniture and making coatings, it and other penetrating finishes are favored by some old-house restorers because they are easy to apply and have a low sheen that leaves the floor looking more Ònatural.Ó Penetrating finishes enhance the natural colors of the particular wood. Though these finishes are slow to set up (several days), and offer a floor minimal resistance to solvent damage and staining (cleansers, water, alcohol, and urine), most scratches can be repaired by simply recoating the affected area. Another advantage of penetrating finishes is that they are flexible and move with the wood. Some people assume stains are also penetrating finishes, but stains only color the wood and offer no protection. Stains can be followed by other finishes, or even mixed with penetrating finishes, depending upon manufacturers recommendations.
How then do you narrow down the finish choices for your old-house floor? Balance your needs with the attributes of each finish. A penetrating finish may be fine for an 18th-century dining room where preindustrial ambiance is important and traffic is low. In a kitchen, however, the strength of polyurethaneÑespecially one of the more traditional-looking, oil-modified products common since the 1980sÑmay be an acceptable compromise on history, especially on a new floor surrounded by appliances. If, say, an oak floor in a Victorian living room has held up well with a classic medium-oil varnish, varnish will continue to do just fine. Whatever your choice, remember it is best to first practice on scrap wood or a test area of your floor to get your desired results. Then keep your wood floors clean, while repairing splinters and loose nails, and they will look their best for many more years.
Peter and Noelle Lord operate Peter Lord Plaster & Paint, Inc. that specializes in preservation and restoration of historic surfaces and all plaster systems (207) 793-2957; www.plasterlord.com.
Start a discussion on this article in our old-house forum!
Subscribe to our email newsletter!