Deck Cleaning and Wood Deck Staining: A Do-It-Yourself Guide

Looking out the back window, you decide that once again it’s 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 deck will look like when it’s finished, but that little hollow in your stomach reminds you how cumbersome cleaning and staining the deck can be. By using the right types of products, the task can be done much easier. The key to a finish to last is all the prep work you do before applying the first drop of stain.

Roof Stain or Sealer: How Do I Choose?

Exterior wood is subject to damage from the elements. The constant cycle of humidity and sun drying will cause deck boards to warp, crack, hollow and chip. It is essential not only to try to seal in the moisture, but also to use an oil-based stain product to keep the wood conditioned. Think of a drop of water placed on your skin. Once the water evaporates, the hydrating effect is canceled. This simplified analogy is similar to placing water-based (or water-based) stain and sealer 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 and keeps the skin more supple. That is why we recommend the use of oil-based products for wooden decking. The oil acts as a better moisture repellent and will delay the drying effect, leading to premature aging. Oil-based sealants will add years of life to your deck.

You may have noticed the change between the words “stain” and “sealant.” Professionals use these words interchangeably. Think of exterior grade wood products as a hybrid of these two words. Roof stain products are actually tinted sealants. You can’t use a stain followed by a urethane sealer or varnish like you would on an interior project. Moisture would attack this combination and your floorboards would turn into a peeling mess. Sealants lock in moisture and the pigmentation in them provides UV protection so the wood doesn’t turn gray. The easiest dyes to maintain will be semi-transparent and deep penetrating oils. Film-forming products, also known as solid stains, will provide good initial protection, but can be prone to peeling and are very difficult to remove. If you don’t have a solid stain on your deck yet, you may want to avoid applying one as there is no going back from that decision.

Starting from scratch: choosing the right terrace cleaning products

Many of the deck cleaners sold at Home Centers, such as The Home Depot and Lowes, contain sodium hypochlorite, more commonly known as household bleach. While bleach is an effective mold remover, it does not solve the problems of dirt trapped within wood or allow for easier removal of grayish wood fibers. Both dirt and greyish wood will contribute to premature finish failure. Furthermore, sodium hypochlorite greatly affects the lignin in wood. Lignin is the “glue” that holds wood fibers together. If you look at a cross section of a piece of wood that has been cleaned with bleach under a microscope, you will see a mess of the fibers. This crossover of the fibers can cause problems with penetration of the dye / sealer. This again means less stain life for your deck, as well as a potentially stained finish. Bleach also causes wood to bleach or wash unnaturally.

Most deck restoration professionals use a two-step deck cleaning process that includes 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 killer. When the dry chemical is mixed with water, hydrogen peroxide and sodium carbonate are released. This oxygenation reaction bubbles dirt and contaminants onto the surface for a deep cleaning effect. This reaction also loosens gray, sun-damaged fibers, allowing them to be gently scrubbed with a medium-bristle brush and rinsed with a garden hose. You can also use a pressure washer set to a pressure below 800 psi to facilitate a faster rinse. Certain types of sodium percarbonate-based wood cleaners also contain other ingredients that help emulsify old, flawed finish.

After finishing the first step of the cleaning process, while the wood is still wet, apply an acid cleaning agent. This will help balance the pH of the deck after cleaning. An added effect is that the wood is lightened and the tone of the deck is leveled. The acids used for this step are usually oxalic, citric, or a combination of both. Oxalic acid can irritate the lungs. After the final rinse, the deck is now perfectly ready to accept the stain / sealer of your choice.

Seal items with a high-quality oil-based sealer

Try to choose your staining products wisely. Paint stores like Sherwin Williams or Benjamin Moore will have higher quality deck stains. As with anything in life, you get what you pay for. Spend a little more upfront 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 nearly impossible for DIY enthusiasts to remove without using harsh caustic chemicals.

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

Roof maintenance

Let the wood dry for 72 hours before putting the furniture back on the deck. As long as the deck stain / sealer is still intact, it’s okay to use a light mixture of bleach and plain dish soap to periodically clean any mold or grime from the surface. By following a simple maintenance plan of repainting the horizontals (floor and handrails) 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.