Redwood, like other natural woods, will eventually change color in the elements. Factors such as sunlight, moisture, and dirt contribute to natural discoloration. Luckily, redwood color restoration is not difficult. Redwood color restoration can be undertaken by homeowners or professional contractors.
Redwood color restoration begins with identifying the cause of discoloration. Mildew, extractive bleeding and iron stain are common causes.
Mildew usually appears as dark spots on redwood’s surface. Severe mildew may be uniform and cover a large area. You can test for mildew by applying a drop of household bleach to the dark spots. If mildew is present, the spots will disappear in one to two minutes.
The process of restoring the original Redwood color begins with scrubbing the surface of the redwood with a mild detergent to remove any mildew. Next, rinse the surface with household bleach. Finally, rinse with water. To remove severe mildew, use a stiff bristle brush and scrub the wood with a solution of one cup of trisodium phosphate (TSP), one cup of household bleach and one gallon of water.
Extractive bleeding is another cause of redwood discoloration. Redwood contains naturally occurring chemical extractives, which are water soluble. If these extractives reach the wood’s surface, they may cause dark staining.
Redwood color restoration for extractive bleeding is accomplished using oxalic acid. Wash the redwood’s surface with one cup of TSP and one cup of household bleach mixed in a gallon of water. Rinse thoroughly and follow with an application of four ounces of oxalic acid crystals dissolved in one gallon of warm water in a non-metallic container. When the wood dries thoroughly, rinse with clean water.
Redwood exposed to iron and water causes the naturally-occurring tannins to react, forming dark staining. This can happen in any species of wood with high tannin content. Redwood color restoration for iron stain can be accomplished using the oxalic acid solution described above.
To learn more about the restoration of Redwood, please visit our Refinishing Redwood page.