When refinishing wood outdoors, you have two main choices of finish: sealers, which prevent wood from absorbing water and delay the weathering process; and stains, which both color and seal the wood.

Semitransparent stains or sealers work best on pressure-treated lumber. Avoid direct sunlight when you're working. Watch the weather: don't apply a new finish if rain is expected within 24 hours.

Use an orbital sander to remove any gloss and smooth out any rough areas on decking boards, railings, or stair treads. Always be sure to wear a dust mask and eye goggles to protect your eyes when sanding treated wood.

Thoroughly vacuum the deck, then apply staining sealer to all deck wood with a pressure sprayer or paint roller. Treat the understructure first, then exposed surfaces.

Use a paintbrush to smooth out drips and runs. Porous wood may require a second coat of staining sealer for even coverage.