Do It Yourself: Choice of finish isn’t always clear
Q. I have a large pressure-treated wood deck that I’ve been giving a clear finish since it was built about eight years ago. I buy the best stuff I can find at my home center but it only lasts about two years and I have to do it all over. I want to switch to a finish that lasts a lot longer. What are my choices and how do I go about refinishing?
A. Clear deck finishes usually have the shortest lifespan of the three popular deck finishes, sometimes needing refinishing in only a year or two, although some more advanced clear products will last three years or so.
One key reason for the relatively short life is a lack of pigment, which gives the finish less resistance to the sun’s ultraviolet rays. The UV causes the finish and sometimes the wood under it to deteriorate. Despite this shortcoming, some deck owners prefer clear finishes because they allow the wood’s natural color and grain to show through.
You can sometimes get an extra year or two between finishing if you use a semi-transparent stain, which will color the wood and give more UV resistance but still let the grain show through.
But the deck finish with the longest life is a solid-color or opaque stain. These stains can hold up for five to seven years or more. Solid-color stains are much like paint, but have some penetrating power, and give the best UV protection of the three popular finishes because of the larger amount of pigment in them. They are available in many colors and are often used for siding, fences and other wood surfaces as well as decks.
If you use a solid-color stain, you won’t be able to see the grain of the wood but the texture will be visible.
Unfortunately, you’ll have to strip the old finish to get good results from a new one. Deck strippers are sold at some home centers and are widely available on the Internet (use a search engine and the words Deck Strippers).
If you buy a stripper, read the directions to make sure it will remove the type of finish you were using – oil-based or latex – and read and follow all the cautions. Deck strippers often contain powerful chemicals and you will need to wear protective clothing and follow directions carefully.
Q. A few years ago I refinished a set of oak chairs with a wax finish. I sanded them and applied the wax, but it hasn’t met my expectations. Now I’d like to refinish them with polyurethane. How do I remove the wax?
A. You are facing the same problem that faces many homeowners who have hardwood floors that have been waxed. When they want to apply polyurethane to the wood, they learn that it won’t stick well because it is almost impossible to remove all the wax. Few experienced furniture finishers use paste wax or finishing wax as a stand-alone finish. Waxes are often used to beautify furniture, but are usually applied over a sealer or other type of finish.
Shellac, lacquer or even polyurethane make good base coats for wax (floors finished with polyurethane should not be waxed). Oak is also a porous wood, and since there is no sealer, wax has probably accumulated deep in the pores.
It’s possible you could get poly to stick if you scrubbed the wood thoroughly with a good commercial wax remover or with mineral spirits (paint thinner), but I would try it on only part of one chair first.
I don’t know of any clear furniture finish that will adhere well to wax, so my inclination would be to stick with the wax-only finish. I’d clean off the old wax, which probably looks dingy now because it is dirty, and apply a top-quality paste finishing wax.