A wood deck requires regular maintenance just like any other major part of a home. Regular cleaning and application of a high-quality stain and sealer will help protect your deck from the weather and ultraviolet ray damage caused by the sun and will extend the usable life of the deck.
Wood deck cleaners come in various ingredients and concentrations for varied applications—spray, scrub and power wash. The purpose of wood deck cleaners is to remove dirt, mold, algae and oxidation (graying).
Because most deck cleaners raise the pH in wood, deck brighteners are important to neutralize cleaners to leave the wood in a neutral state.
Cleaners containing chlorine bleach are commonly used to clean decks but they are not recommended for cleaning treated wood. Excessive use of chlorine bleach containing cleaners (sodium hypochlorite or calcium hypochlorite) can damage treated wood leaving it with an unnatural whitewashed appearance. Chlorine bleach also can raise the wood fibers and cause a fuzzy-looking surface.
Chlorine bleach (sodium hypochlorite) breaks down the lignin in wood causing excessive damage to wood cells. The natural pH of wood is slightly acidic, and bleach is a basic solution. As a result, use of bleach on wood shifts the pH from near neutral pH to a basic pH that will damage the cellular structure.
- Bleach corrodes metal fasteners, screws and nails.
- Bleach can cause damage to surrounding plants.
- Bleach, after several months, lightens wood's natural color.
- Bleach does not eliminate the spores from which mold and mildew grow.
- Hydrogen peroxide is environmentally friendly and a safer substitute than bleach. Its chemical formulation is H2O2. As the oxidizing process releases the excess molecule of oxygen, H2O (water) remains as its residue. For tough jobs, hydrogen peroxide kills the mildew on contact within several minutes.
- Oxygen bleach is sodium percarbonate, an environmentally friendly and excellent detergent and bleaching agent with a hydrogen peroxide base. Sodium percarbonate is a cleaning and bleaching agent with a strong fungicide effect. It has been tested and found to be more effective attacking the deeper-rooted organic growth on the porous wood surfaces.
Sodium percarbonate is a white particle powder, nontoxic with no contamination, nonflammable, non-explosive, and soluble in water. It is also biodegradable and leaves no harmful by-products or residues that can harm the environment. Sodium percarbonate is effective in cleaning most average wood preparation jobs.
- Sodium percarbonate is a chemical formulation is an adduct of sodium carbonate ("soda ash" or "washing soda") and hydrogen peroxide (that is, a perhydrate) whose formula is more properly written as 2 Na2CO3 · 3 H2O2.
- Apply oxalic or citralic acid (deck brightener) after using sodium percarbonate or hydrogen peroxide in the cleaning process. The deck brightener will restore the wood to its natural pH and neutralize the sodium percarbonate cleaner. This will provide a beautiful finish when applying the final stain.
The formula of oxalic acid is C2H2O4. Its usual form is that of the crystalline hydrate, (COOH)2·2H2O. Citralic acid is a specifically formulated blend of acids and surfactant and was designed to neutralize and brighten quickly without unwanted bleaching or damage to the wood. This is the step professional restoration contractors use to achieve that like-new look of fresh cut wood.