This summer, as you fire up the grill, you may notice that your deck lacks the luster it may have had when it was new. Before you run to the store and stock up on wood cleaner, take some tips from researchers at the Forest Products Laboratory (FPL).
The popularity of wood decks (and the desire to keep them looking bright and new) has led to a proliferation of commercial cleaners and brighteners. The active ingredient in many of these products is sodium percarbonate, which although a bleach, is an oxygen bleach rather than a chlorine bleach (like the one found in your laundry room).
Oxygen bleaches can remove growths such as mildew, and have been reported to be less likely to damage wood surfaces than a chlorine bleach, particularly with low-density woods like western redwood and Alaska yellow-cedar.
It is difficult to compare the advantages and disadvantages of oxygen and chlorine bleach, however, due to the wide range of ingredient concentrations, additives, and differences in wood substrates that have been used to evaluate the cleaners. If you look closely though, the active ingredient in some cleaners may actually just be household bleach—though some may have a special detergent to enhance the product’s cleansing properties.
At the extreme end of cleaner spectrum are products which use sodium hydroxide. Sodium hydroxide is a strongly alkaline chemical that pulps wood and is used in some paint strippers. These cleaners may be used, but only as a last resort, for example when mildew is embedded in a surface finish.
Some manufacturers advertise that their cleaners or brighteners restore color to wood, but cleaning wood does not add color. Removing mildew reveals the original color and brightening the wood may make it appear as if it has more color. If you want to restore color, stain the wood.
Some commercial “cleaners” simply pulp the wood surface and then require power washing to remove the product (and the wood). In this case, the color is “restored” because the surface of the wood is removed. Sanding will give the same result over these high-priced alternatives.
There are a lot of choices for wood cleaners and brighteners out there, but before you make any decisions, consider your needs and the product’s ingredients. Being an informed consumer will ensure that your deck looks its best this summer, and that you’ll have some extra change left over for another round of brats for the grill.
The information in this blog post was adapted from the Forest Product Laboratory’s (FPL) Wood Handbook: Wood as an Engineering Material