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Wood Protection

It's springtime, and neighborhoods are full of the sights and smells of homeowners staining, painting and varnishing their decks, siding and fences. If you'll be joining the brush brigade, here's some information to make your project easier.

Photo Courtesy Wolman
At the Lumberyard 

Planning on building a deck or gazebo, or adding a fence to keep the kids or pets on the premises? Lumberyards and do-it-yourself centers offer a wide range of wood products, treated with various types of coatings intended to preserve and protect the wood from the environment.

Coatings are used for two reasons: to protect and to beautify, notes Peter Hope, technical specialist with Massachusetts-based Cabot, manufacturer of wood-care products. The protection comes from the binders: 100 percent acrylic resin in water-based, and alkyd and natural oils in solvent-based coatings. Pigments give the coating protection from ultraviolet rays and allow the customer to choose from a wide range of colors.

Factory finish lumber coatings, which seal all sides and ends of the boards, protect against the three most damaging effects on wood: UV rays, moisture and temperature change. Board cuts should be sealed with a preservative solution such as a copper naphthenate solution containing at least 2 percent copper. (Go to for a list of brand names.)

When choosing among clear, semitransparent, solid color or paint, Hope says that while all options protect the wood from UV rays and moisture, the difference is the longevity (the time in between applications). The more pigment in a formula (such as what is found in solid-color stains and paint), the longer the coating will hold its color and the less maintenance will be needed.

If you buy uncoated wood, apply the coatings as soon as possible, and avoid letting the wood weather, which breaks down the top level of wood fiber. But Hope cautions that, when it comes to penetrating stains, if you apply the stain too heavily, it will fill up the wood cells and keep the wood from drying properly.


The End-Tag Story

Before you buy that 2x4, take a moment to peruse the end tags attached to the lumber. According to the American Wood Preservers Institute, end tags on lumber treated with chromated copper arsenate (CCA) typically include warranty information, manufacturer and/or bar code and other information, including basic safe-handling information and a condensed version of the Consumer Safety Information Sheet.

The restriction against using CCA to treat wood for residential use generated a transition to arsenic-free preservatives, which began more than two years ago, says Jim Hale, executive director of the Wood Preservative Science Council. Consumers can choose from wood treated with alkaline copper quaternary (ACQ) or copper azole (CA). It is important for consumers to understand that wood preservatives are highly regulated by the Environmental Protection Agency. Both of these products are approved and registered by the EPA, Hale says.

With CCA alternatives, it's critical to match the type of coating and its retention with the intended application (aboveground or ground contact). While end tags contain some basic information €

such as the type of formulation used, the treating company and the intended exposure or end-use €

you might want to contact the manufacturer for further details.

Finally, check for the quality mark or symbol from a U.S. Department of Commerce American Lumber Standard Committee (ALSC) accredited agency on the back of the end tag, ensuring that the wood has been treated to standard specifications.


Wood Coatings DIY-style

There are two basic finish types: film-forming finishes (paints, solid-color stains and varnishes) and wood-penetrating finishes (preservatives, water repellents and pigmented semitransparent stains). Generally speaking, acrylic polymers are more resistant than oil-based paints to sunlight, according to a Forest Products Laboratory finishing factsheet. However, woods like redwood and cedar have water-soluble extracts that bleed through latex paints, and they require an oil-based or stain-blocking latex primer.

Life span between recoatings can range from one year for water repellents to two or three years for varnish and seven to 10 for paints, depending on the type of finish and its exposure to weather elements and sunlight. A structure's north face requires less frequent repainting than the other sides.

No one likes to spend all summer coating a fence or deck, only to face a recoat routine every few years. Choosing the right product for both looks and longevity can result in less work time and more summer time.


Nancy Christie is a freelance writer based in Youngstown, Ohio.