PRO Deck Doctor – Park City Custom Decks, Deck Restoration, Deck Builder
The solutions used to clean wood can have a great impact on the overall performance of the topcoat. Sometimes even more importantly these cleaning solutions can negatively impact the integrity of the wood itself. All too often we think that the once a tree is felled, and milled that it is no longer “alive.” This is far from the truth.. In fact many species of wood can propagate long after it’s stacking in the log pile.
For the sake of discussion here let’s look at Redwood and Cedar. These woods are filled with a components know as extractives. These are organic compounds like tannins, flavonoids, quinones and lignans and water-soluble compounds such as carbohydrates, alkaloids, proteins and inorganic material. Woods containing extractives require special attention with regards to cleaning solutions.
Cleaning solutions have adverse effects on these compounds. Reactions such as discoloration, compositional breakdown, and actual wood deterioration can just some of the negative effects. Special attention needs to be taken with woods like redwood and cedar to avoid catastrophic reactions.
Many over the market cleaners contain bleaches and phosphates. These chemicals are invisible in the over effects. But they breakdown the structural fibers in the wood and over time can result in a depreciated lifespan of the wood itself. Bleaches on wood should be avoided unless recommended by the topcoat manufacturer. Yes, there are topcoats on the market at require bleach be used as a cleaning agent. The reason for this is that a chemical bond occurs between the bleach residue and the acrylics used.
Oxalic acid is perhaps the most common cleaner used on Redwood and Cedar. Both of these woods are relatively high on the Ph scale. Subjecting these woods to an influx of acid reinvigorates the extractives and thereby returns the wood to it’s truest color and hue. When ever applying a pigmented or dyed stain be sure to achieve the best hue, otherwise the finish product will not be the desired color.
Some cleaners contain Sodium Hydroxide. This is very low on the Ph scale and the reaction that occurs can be a very dark discoloration.
This is normal. To reverse the darkening use an acid wash solution, and the effects will reverse almost instantly.
We recommend using environmentally friendly cleaning solutions for the most part. There are times that the concentration needs to be altered in order to achieve the desired affects. Mold and mildew react poorly to acidic concentrations.. Heavy basic solutions will have a greater impact in eradicating these types of issues. In the end it still remains critical to balance the wood to the correct Ph. Without getting too technical, it is better err on the acidic side with woods such as Redwood and Cedar. Some exotic hardwoods, however, require just the opposite.
A recent development in the cleaning are the use of per chlorates. The reason woods turns gray is that it oxidizes. Which means woods reactions with the oxygen in the atmosphere and begins to breakdown. The severity of the reaction depends on many conditions, not the least of which is the level of humidity for your specific geographic location. The New England area, which is very humid experiences this change fairly readily. And in fact is often desired. Per chlorates halt the oxidation reaction and restores the natural color of the wood.
Redwood and Cedar are known as decay resistant woods. We use them primarily because in moist, humid, conditions these woods resist decay from the elements and from lower plant forms and from insects. Left untreated these woods perform exceptionally well. Topcoats are used as a preservation thereby resisting or retarding this oxidation process. In higher elevations however, the oils in the topcoats actually prevent wood deterioration from Ultraviolet exposure.
Using chemicals to clean your wood deck can very effective. However, one needs to be attentive to the chemicals used in order to achieve the desired results. The wood planks on the deck are still very much alive in so much as they possess nature’s decay resistant properties. Robbing the wood of these chemical compounds can reduce the performance of topcoats and of the life expectancy of the wood itself. A well maintained healthy deck can last generations.