Looking out the back window, you decide that once again it is time to prepare your deck for the upcoming season. The grill still has its winter cover and the patio furniture is stacked in the corner. You can imagine what the platform will look like when it’s finished, but that little pit in your stomach reminds you how messy cleaning and staining the platform can be. If you use the right types of products, the task can be accomplished much more simply. The key to making a finish last is in the prep work you do before applying the first drop of stain.

Deck Stain or Sealer – How Do I Choose?

Exterior wood is subject to damage from the elements. The constant cycle of wetting and drying in the sun will cause deck boards to warp, crack, cup, and splinter. It’s essential to not only try to seal out the moisture, but also to use an oil-based staining product to keep the wood conditioned. Think of a drop of water placed on your skin. Once the water evaporates, the moisturizing effect is cancelled. This simplified analogy is similar to putting water-based (or water-based) stain and seal products on your deck. Using the same analogy, now think about putting a drop of baby oil on your skin. The oil acts as an emollient keeping the skin more supple. That’s why we recommend using oil-based products for wood decks. The oil acts as a better moisture repellant and will delay the drying effect, which leads to premature aging. Oil-based sealers will add years of life to your deck.

You may have noticed the switch back and forth between the words “stain” and “sealant.” Professionals use these words interchangeably. Think of outdoor wood products as a hybrid of these two words. Deck staining products are actually tinted sealers. You cannot use a stain followed by a urethane sealer or varnish as you would on an interior project. Moisture would attack this combination and the floorboards would become a mess. Sealers lock in moisture, and the pigmentation they contain provides UV protection so wood doesn’t turn gray. The easiest stains to maintain will be semi-transparent and deep penetrating oils. Film-forming products, also known as solid stains, will give good initial protection, but can be prone to peeling and are very difficult to remove. If you don’t already have a solid stain on your deck, you may want to avoid applying one, as there is no going back on that decision.

Starting over: choosing the right terrace cleaning products

Many of the deck cleaners sold at Home Centers like The Home Depot and Lowes contain sodium hypochlorite, more commonly known as household bleach. While bleach is an effective mildew remover, it does not address problems with dirt trapped within the wood or allow for easier removal of graying wood fibers. Both dirt and grayed wood will contribute to premature failure of the finish. In addition, sodium hypochlorite greatly affects the lignin in wood. Lignin is the “glue” that holds wood fibers together. If you were to look at a cross section of a piece of wood that has been cleaned with lye under a microscope, you would see a jumble of fibers. This cross-weaving of the fibers can cause problems with stain/sealer penetration. Again, this means less stain life for your deck, as well as a potentially stained finish. Bleach also causes the wood to bleach or wash unnaturally.

Most deck restoration professionals use a two-step deck cleaning process that involves a landscape-friendly cleaning agent called sodium percarbonate, followed by an acid-based cleaner to balance the pH. Sodium percarbonate is considered an effective mold remover. When the powdered chemical is mixed with water, hydrogen peroxide and soda ash are released. This oxygenating reaction bubbles up dirt and contaminants on the surface for a deep cleaning effect. This reaction also loosens sun-damaged gray fibers, allowing them to be gently scrubbed with a medium-bristled brush and rinsed off with a garden hose. You can also use a pressure washer set to less than 800 psi to facilitate faster rinsing. Certain types of sodium percarbonate-based wood cleaners also contain other ingredients that help emulsify the old, deteriorated finish.

After completing the first step of the cleaning process, while the wood is still wet, apply an acid cleaning agent. This will serve to balance the deck after cleaning. An additional effect is that the wood is illuminated and the tone of the terrace is evened out. The acids used for this step are usually oxalic, citric, or a combination of both. Oxalic acid can irritate the lungs. After your final rinse, the deck is now perfectly prepared to accept the stain/sealer of your choice.

Seal the elements with a high-quality oil-based sealer.

Try to choose your staining products wisely. Paint stores like Sherwin Williams or Benjamin Moore will carry higher quality wood deck stains. As with anything in life, you get what you pay for. Spend a little more up front and you may not have to stain your deck as often. Avoid products that contain acrylics. These products will build up over time and create a finish that is almost impossible for DIY enthusiasts to remove without using very strong caustic chemicals.

The application of the sealing product can be done by spraying, brushing or scrubbing. If you spray, be sure to brush the product in with a porcelain bristle brush to get it into the wood and prevent bleed-through. Most oil stains should be applied in what is called a wet-on-wet coat. The first coat is applied and allowed to penetrate into the wood. Within a short period of time before the product dries, apply another coat. Be sure to always follow the manufacturer’s recommendations and the instructions on the can.

deck maintenance

Let the wood dry for 72 hours before putting the furniture back on the deck. While the stain/sealant on the deck is still intact, it’s okay to use a light mixture of bleach and dish soap to periodically clean any mold or grime from the surface. By following a simple maintenance plan of recoating the horizontals (floor and railing) every year with a light coat of oil and doing the rail system every two years, your deck will always look fresh and last a lifetime.