How to Clean, Seal or Stain a Deck – Tips from Zebra Deck

Surface Preparation

Cover and / or hose down all surrounding landscaping -- grass, plants and vegetation -- before and after using a wood cleaner or stain-stripping product.
Do not use chlorine bleach (sodium hypochlorite) alone to clean / restore outdoor wood. It will interfere with a coating’s adhesion and penetration, and will not completely remove ground-in dirt or the weathered gray surface fibers that make the surface look aged and soiled. Products specifically formulated to a) loosen and lift degraded surface fibers and other surface contaminates, and b) remove stains from wood extractives and fungal growth are recommended for optimal surface restoration.
Dark stains found on Cedar and Redwood surfaces are most often the result of tannin bleeding, which can be remedied. Tannin is just one type of organic material that occurs naturally in decay-resistant species, and can be extracted to the surface by certain solvents, including water. Because tannin is water-soluble, mild discoloration can often be removed with detergent and water. Stubborn tannin stains can be removed with an oxalic acid-based wood cleaner.
ALWAYS perform a "Splash Test" before applying a new stain or a maintenance re-coat. Splash water on several sections of your wood structure, and observe if the water is absorbed. If the water beads or is not absorbed within 15 minutes, the surface will not absorb a coating properly. Use a wood cleaner / restorer to remove the repellency or allow the wood to weather for several weeks, then test again. Cleaning or weathering will allow the wood pores to open and better absorb the stain.

Products

Features

Any coating that is “clear”, i.e., without pigment, will not provide protection against UV exposure. A finish coating must contain pigment in order to block, absorb or reflect damaging UV rays. Stain pigment protects your deck's surface much like sunblock lotion protects your skin: both prevent the top surface layer from drying out and aging prematurely.

When dry, oil-base products will provide a deeper, shinier finish on the deck surface, while water-base products produce a flat, or matte appearance. Be sure to follow the product label's directions on recommended number of coats, so that you achieve the product's intended finish look.

Recommended Uses

To protect wood decks or other structures exposed to constant shade, which promotes the growth of mildew, consider using a water-repellent with a preservative. The preservative will give your deck added protection against fungi growth, including mildew, mold, rot and decay organisms.

To protect wood decks or other structures exposed to severe heat and sun exposure, use an acrylic stain with transparent iron oxide or opaque pigments. Stains with this make-up will provide your deck with longer color retention than transparent stains or toners, giving your wood maximum protection against graying and surface degradation.

Application

Job Preparation

Remove BBQ grease from the deck surface before applying a stain. Automotive degreasers or carburetor cleaners (water-rinseable) are effective in removing these grease stains.
Mix multiple gallons of the same colored product together in a larger container to safeguard against color variation between gallons. This is especially important if product was purchased at different times or from different store locations.
Always do a sample brush-out to observe the appearance of your stain on your specific project surface. A stain color and sheen level will vary depending on a wood’s age and species, surface porosity and the method of application.

Procedures

Do not apply a stain immediately after a rainfall. Water-soaked wood should be dry out for 24 hours so that it can absorb a penetrating oil properly. For best results, apply stain when precipitation-free weather is expected 24-48 hours before the project begins and after it is completed.
Avoid applying finish coatings during the hours of most intense sunlight, if at all possible. Direct sun coupled with a hot surface can cause coatings to dry with an uneven appearance. If applying a water-base stain to wood that is hot to the touch, dampen with water to cool.
Do not over-apply a finish coating. Wood pores operate similar to a sponge; they can only absorb so much of a stain before they become saturated. Over-application will cause excess product to sit on the wood surface, which will lead to problems with tracking and premature failure.
It is not necessary to coat the underside of wood simply to protect it. The underside is not subjected to sun or significant water exposure, therefore, it does not require a protective barrier coating. Additionally, if it is pressure-treated wood, it will prevent invasion of wood boring insects and rot and decay organisms.
Remove any over-spray, drips or splashes before they dry to make clean-up easier. Wet product can be cleaned up with fresh water in most cases. If product has dried, use mineral spirits, lacquer thinner or a spot remover. See the Product Technical Data Sheet for your chosen coating for specific Clean-up instructions.

Compatibility

Do not apply a water-repellent sealer over an existing paint or stain. A water-repellent product must penetrate into the wood to perform effectively, and will not be able to penetrate an existing coating.
Do not tint or thin products, unless directed to do so on the product label. Altering a stain product without specific label instruction will void its warranty.
Similar colors of the same product may be combined to create a new shade.

Maintenance Tips

water puddles sit on a deck or porch for more than two days, brush them off. Standing water can cause mildew to form on the surface of a stain.
Pitch stains, or crystallized sap, found mainly around the knots of pressure-treated wood, can be removed with turpentine or simply scraped away. Turpentine will not harm an existing stain. Pitch is a non-water soluble, organic wood extractive material found in species such as Ponderosa, Southern and White Pine.
Do not use a metal shovel to remove snow from a deck; it can pierce the underlying coating and cause it to erode
Only use sodium chloride (i.e. Halite) types of salt on a wood deck or porch that has been water-sealed or stained. Calcium chloride salts will reduce the effectiveness of a water-repellens.