3 ways to refinish wood floors and furniture
Shannon Lee | Improvement Center Columnist | June 8, 2015
A gorgeous hardwood floor. The perfect wooden farm table. The stunning chairs that go along with it. All of these items have one thing in common, besides their materials and beauty: They probably have some sort of wood finish. If that finish has seen better days and needs freshening up, or if you are considering changing the look altogether, you must figure out what the original finish was before you go any further.
A brief history of wood finishes
Everything evolves with time, and that includes wood finishes. The earliest hardwood floors were rarely finished with anything at all, and simply allowed to weather and age as they liked. This is especially true of tight-grained varieties in the North, such as Eastern white pine, and resinous heart pine in the South. If these early woods were finished at all, it was with hand-rubbed wax or linseed oil to provide a bit of protection.
After 1860, things changed a bit when clear, hard finishes became popular. Oak was often covered with varnish to protect it from water, but after 1910, man-made resins became the finish of choice. The 1960s changed things once again, with the introduction of polyurethane varnishes.
Some old homes have been graced with owners determined to restore rather than renovate, and that means floors and furniture might have the original finishes -- or none at all. But it's usually not that simple to figure out what is actually on the wood. That's where careful testing comes in.
Identifying wood finishes
There are two types of finishes: those that sit on the wood and those that penetrate. Surface finishes coat the wood, forming a hard layer of protection. These finishes include shellac, varnish, lacquer, polyurethane, and waxes. Penetrating finishes sink into the wood, enhance the beauty, and make it easier to correct small blemishes and scratches. The most common penetrating finishes include linseed oil, tung oil, and some specialty oils, such as walnut or lemon.
You can begin identifying the finish by trying a few field tests. Begin by carefully scraping at the wood to see what happens. If you can scrape up a reside that appears to be waxy or gummy, it might be a simple layer of wax. If you can't scrape up anything but the floor is very shiny, it's likely polyurethane. With penetrating oils, there is no hard sheen on the wood, and you can feel the grain under your fingertips.
For surface finishes, go further with a solvent test. Choose a spot that is hidden away in a corner of the room or underneath the piece of furniture. Apply a few drops of denatured alcohol, wait a few moments, then touch the area with a cloth. Shellac will soften and become sticky.
If it doesn't, move on to the next step, which includes a touch of lacquer thinner. Using just a few drops, try the same test. If the finish softens, you probably have lacquer; if it just becomes tacky, you need to figure out if it's water-based. You can do this by using a xylene solvent for the third test. Xylene will turn water-based finishes into a gummy mess. If none of these tests work, you are looking at a finish that must be sanded away, such as varnish or polyurethane.
Refinishing floors and furniture
Once you know what finish you have, you can take steps to remove it. There are three basic ways to strip away the old finish: Sanding, solvents, or chemical strippers.
- Sanding is excellent for removing paint, varnish, acrylic, lacquer, or shellac. Deep sanding might also cut through penetrating finishes. Use sandpaper for smaller areas, but turn to the random orbit sander for larger spaces. Take your time in removing the resulting dust, as the tiniest spot of the old finish can make your new finish look and feel uneven.
- Solvents work well for shellac and lacquer. Start with denatured alcohol, then move to lacquer thinner if the alcohol is not enough. Generously apply the solvent with a rag, then scrape away the finish with a putty knife. Remember to use these solvents in a well-ventilated area.
- Chemical strippers are harsher, and thus they work well on polyurethane, paint and varnish. Apply them exactly as directed on the label, and always use them in a well-ventilated area. It's also a good idea to wear safety gear as you handle the chemicals, as they could be dangerous if splashed onto eyes or skin.
Removing the previous finish is very important, as some finishes interact with each other to create a gooey, sticky mess. Besides that, a single finish on your floor looks much better than a hodge-podge of different types. Before choosing your new finish, be sure to test it on an inconspicuous area to ensure you like what you see.