Stain will improve the appearance of your deck while helping to protect it from the elements. It's easy to forget about the cracks between the boards, but staining them as well will help protect and beautify your deck. It takes just a little longer to stain the cracks, but the results will be worth the extra effort. Like any job involving staining, painting or clear coating, you must start with a surface that's completely clean.
Cover landscaping and plants with plastic sheeting.
Remove all furniture and hanging plants from the deck and sweep the deck clean of all debris. You don't have to remove items permanently attached to the deck unless you want to. If you leave a hanging plant holder, for example, mask it off with painter's tape after washing the deck but before staining it.
Mix deck cleaner with water in a garden sprayer according the cleaner manufacturer's directions.
Spray the entire deck with the cleaning mixture and allow it to set. Follow the manufacturer's directions for how long you should let it set -- usually 15 to 30 minutes.
Scrub between the cracks as much as space will allow.
Pressure wash the deck at 1,000 pounds per square inch. Use a 40-degree spray pattern nozzle. Don't attempt to angle the pressure washer's wand to reach between the cracks.
Allow the deck to dry for 24 hours. Since you're staining inside the cracks and they may not be exposed to air as much as the rest of the deck, you might need to wait 48 hours.
Dip a narrow sponge or thin paintbrush into the stain. The size of the sponge or paintbrush will vary depending on the width of the crack.
Start at one end of the crack and apply stain to the sides of the deck boards that form the crack. Stain both sides of the crack. Be attentive and wipe up residue as you go in order to avoid leaving drips or small puddles of stain that will cause the edge of the crack to be darker than the rest of the deck around it.
Continue until all the cracks are stained, then stain the remainder of the deck.