During and after construction, logs can be stained by rain hitting logs and leaving water stains, plus black spots develop from water hitting nails, spikes or lag screws used in construction and leaving unsightly stains black on logs and other woods. This can be easily removed using several methods:
- Oxalic acid For black nail stains you can use oxalic acid and water. One cup of oxalic acid in a gallon of warm water is the best mix for normal stains. If you have any stains, just rub the solution with a soft cloth and voila … they will disappear. If you have a lot of stains or want to rinse the logs before staining the house, you can use a hand pump sprayer for the job. This solution is poisonous, so keep it away from any living thing. Also wear eye protection and a mask to filter out any of the chemicals. This chemical is available in most household centers and is known as “wood bleach.”
- Bleach and water Another way to light and clean logs or deck before finishing is to use a mixture of half house bleach and half water. This can be sprayed with a hand pump sprayer and can be worked with a brush in the tough spots. Never try to make your own super stain remover and mix oxalic acid (wood bleach) and household bleach. This will emit a huge volume of harmful fumes that can damage your lungs.
- Sodium percarbonate (CPR) CPR is used to clean and shine uncoated wood that is dirty, discolored, or gray from UV exposure. Mix CPR with the concentration of new construction polish solution just prior to staining to remove dirt and grime from logs during the construction process and to break up grinding enamel. Mixed to Log Cleaning Solution Concentration – Use for periodic cleaning of stained logs to extend the life of your stain. It can be easily applied with a garden sprayer.
- Phosphoric acid Phosphoric Acid is a liquid concentrate for cleaning log and wood surfaces. It is commonly known as the Log Wash. It can be used as a maintenance cleaner or to prepare the wood surface for a new coat of stain or finish. The exterior surfaces of a log home are a hotbed for dust, pollen, and other airborne contaminants that dull the surface and encourage mold growth. A light cleaning once or twice a year will keep a home beautiful and help extend the life of the exterior wood finish. To prepare bare or finished wood surface or for a new coat of stain or top coat, Log Wash removes surface dirt, grime, pollen and mold without damaging the wood or finish. Unlike bleach solutions, Log Wash does not alter the natural pH balance of the wood, thus preventing wood fiber damage and iron tannate stains. It can be easily applied with a garden sprayer.