How to Revive Dull, Faded Exterior Redwood for a Vibrant, New Look
Restoring the color of exterior redwood after it has discolored due to sun, moisture, temperature, microorganisms, dirt, and soot can require a bit of elbow grease but it can be done. Identifying the source of the discoloration is the key to developing a successful restoration plan.
Mildew is a common cause of discoloration for exterior redwood. To test for mildew, apply a drop of common household bleach to the small, black spots. If the spots disappear after a few minutes, then mildew is likely the culprit. To remove mildew, scrub the surface with a mild cleanser or detergent and then rinse with household liquid bleach and water. For more severe cases, use a stiff brush to scrub the wood with a solution of TSP, household liquid bleach and water.
Extractive bleeding, the result of naturally occurring extractives in the wood, is another cause of discoloration in exterior redwood. It may cause some boards to turn very dark, or may make paint or other finishes drip over the wood. To remove extractive stains, an oxalic acid solution should be applied to a small discolored area. If it fades and disappears within twenty minutes, wash the wood with TSP, household liquid bleach and water. Once the wood has dried, an application of four ounces of oxalic acid crystals dissolved in one gallon of warm water should finish the job.
The presence of iron and water can cause the formation of a dark, blue-black iron tannate precipitate. This reaction is more likely to occur over time on areas with iron hardware, and requires noncorrosive hardware to prevent. Discoloration can be light or heavy, but if the wood appears healthy, washing with a solution of TSP and household bleach followed by the oxalic acid treatment should lighten and restore the color.
Another cause of discoloration may be ink or sawdust. In this case, the usual TSP and bleach solution followed by the oxalic acid treatment should do the trick.
The best way to prevent discoloration in exterior redwood is to protect it with a finish. For decks and siding, use a quality, mildew-resistant product. For siding, use a water repellent or water repellent finish. Quality latex paints, stains or finishes designed for redwood should protect wood from the elements for years. Regular cleaning and recoating with quality finishes will prolong the life and beauty of exterior redwood.