Deck Maintenance: Using Wood Brighteners
Staining your wood fence or deck can be a hair-tearing affair if not done properly. It’s frustrating to brush on a deck or fence stain only to find out it was applied unevenly, or that previous blemishes in the wood continue to show through. For best results when staining a wood deck or fence, it’s important to first ensure that the wood is as clean as possible so that the stain penetrates evenly.
A carefully chosen fence or deck brightener with oxalic acid can help achieve this goal, yet many homeowners skip this important step when applying fence or deck stain. Here’s a primer on what to look for in a wood brightener and how to use it.
What is oxalic acid?
Oxalic acid is the primary ingredient in brighteners for cedar decks and fences. It’s often used by professional contractors before a refinishing project to:
Remove unsightly blemishes. Leaves, twigs and other organic matter that lands on your fence rails or deck surface can “bleed” onto the wood, leaving tannin stains. A wood brightener gets rid of these, as well as any mildew or rust stains.
Improve stain penetration. The most important goal when staining a wood fence or deck is to allow the stain to permeate the wood as much as possible. The better the penetration, the longer the stain will last and the more protection it will provide. Too much moisture in the wood can hinder this process. Using a wood brightener before you stain will open up the pores of the wood and allow more stain to seep in.
Restore the appearance of old, weathered wood. Stain doesn’t cover the wood like paint; it only enhances what’s already there. The better the initial surface looks, the better the finished surface will look. A fence or deck brightener will give you a better-looking surface to start out with.
Neutralize stain remover. If your fence or deck restoration project requires a stain or seal remover to get rid of past layers, the remover can darken the wood and even weaken subsequent stain coatings. A good cleaning with oxalic acid not only brightens up the wood again, but it neutralizes the stain remover so it won’t affect your new coat of stain.
Should I use a wood brightener on a new fence or deck?
The fresh wood of a new fence or deck may not need brightening, but it still needs prep work before you stain it. New wood can contain “mill scale,” a flaky surface of iron oxide, hematite and magnetite, which can lead to a blotchy stain job. Applying oxalic acid will both clean the new wood and make it more receptive to staining.
How do I use a wood brightener?
Before applying the product, clean off as much surface dirt as possible by hosing, power washing (carefully) or scrubbing with a mild detergent. Then simply spray the brightener on with a garden sprayer, let it sit for 15-20 minutes and rinse; no scrubbing is required. Follow the manufacturer’s recommendations for whatever product you’re using.
What do I do after I apply the brightener?
After rinsing off the brightener, you’ll need to allow your fence or deck to dry thoroughly, which takes about 2-3 days in warm, sunny weather. To be certain your deck is dry enough, you can use a moisture meter, a nail-like device that’s tapped into the end of a board. The wood is ready for staining when the moisture level reaches about 18 percent.
Skipping these steps and going straight to staining your fence or deck is not a wise maneuver. However, by taking your time, using a wood brightener and taking the proper precautions, you will be able to produce a quality stain job that will protect the wood from sun and rain.
~Ben Anton, 2010