1. Due to the growing popularity of decks, there are now a wide variety of deck finishes from conventional, oil based, penetrating ones to new water based latex ones. Oil finishes come in clear, semi-transparent and opaque finishes. While the Water based latex finishes come in solid color stains. Its my experience that even the best oil based finishes only last 3 or 4 years tops with the latex finishes lasting slightly longer.
2. So to begin prepping your deck for staining, begin by pressure washing the surfaces. You want this process to remove dirt and debris but not wood! Do not get so close to the surface with the pressure washer tip that it leaves "lap" marks, dimples or holes. If you are going to be using a clear or semi-transparent finish, there are deck brightening products that help restore the deck to that "new wood" look. Don't forget that all surfaces to be stained need to be cleaned. That means all four sides of the rail spindles and both sides of the rial
3. Once you have let the deck dry for 24 hours, start by sweeping the deck off just to make sure all surfaces are clean and debris free. Next start be using a brush on the outside of the deck, on the tops of the railing and work you way down to the deck surface. Then in toward the house. Now, once your brush work is done, switch to a roller for the deck surface. (To save your back, use an extension poll with your roller frame - that way you can stand and roll) Start at the outside edges and work toward the house. Basically you are trying not to paint yourself into a corner. Use even pressure on the roller and on each board. Overlap your coverage areas to give uniform coverage and sheen. Apply a second coat if necessary.
4. Spraying is of coarse another way to coat deck surfaces. Usually as pros we use a combination of all these methods to save on time. But if you opt for this option you must protect all plans and shrubs from overspray. Spray equipment can be rented at most paint store or equipment rental companies. Check with a paint professional for tip sizes and pressure settings when using stains. Spray railings first, unless the railings are to be a different color than the deck. Then the deck should be coated first. One trip for protecting plants or other objects from overspray is to tape Kraft paper to the outside of the railing, which will catch the overspray. When spraying the deck itself, spray evenly over a six foot square area, then go over that area with a 3/8inch nap roller to spread coating evenly into deck. Continue this procedure in sections until deck is covered. Be sure to use a large shield (such as 4 ft square piece of cardboard) when painting alongside the house to protect it from overspray.
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