It's deck sprucing-up time. Here are some tips on staining from Debbie Zimmer at the Paint Quality Institute.
Assuming that your deck doesn't need repairs, the first step is to remove any loose paint or stain. You can do this one of two ways: by scraping and sanding, or by treating the surface with a commercial deck conditioner, followed by careful power washing with plain water.
The prep work can be even easier if the deck has no loose paint or stain. Clean the surface with a commercial product, or, to save money, make your own by mixing a cup of household bleach and a splash of soap with a gallon of warm water. After scrubbing the surface clean, rinse it thoroughly using a garden hose.
If, even after cleaning, you have areas with stubborn mildew, apply a solution of three parts water to one part bleach, allow the solution to sit on the affected surface for 20 minutes, then scrub off the mildew and rinse the surface clean, Zimmer said.
Once the surface preparation is complete, pick your stain. There are solvent-based and water-based formulations, but water-based stains offer significant advantages: They have better resistance to weathering, they dry more quickly, they are relatively odor-free, and they clean up with plain soap and water.
Another consideration is whether to use a clear deck finish or a pigmented stain. This decision might be dictated by the condition and color of the wood on your deck, but durability is another important concern.
Clear-wood finishes provide only limited protection from the sun's UV rays, so they need to be reapplied every 12 months or so; pigmented stains afford more UV protection, so they last longer.
There are two types of pigmented stains. Semitransparent coatings help protect the wood without hiding its grain or texture, and solid-color stains show texture but not the grain.
Semitransparent stains must be reapplied every 12 to 18 months, but solid-color stains can last three to five years, so if you want to stretch out your application cycle, go with a solid-color finish.
Consider the stress a deck endures, including standing water, snow and ice, foot traffic, abrasion from patio furniture, and direct sunlight.
Zimmer said that top-quality 100 percent acrylic latex stains — either semitransparent or solid-color — are perhaps the best option when restoring a deck.
"They're tough and durable, and many of these stains contain extra ingredients to help prevent mildew," she said.
Stains can be applied with spray equipment or a long-handled roller, or by brush.
"However, spray or roller application should be followed by back-brushing," she said. (That means going back in and brushing the stain while it's wet so it better penetrates the wood.)