The silvery patina that is characteristic of naturally weathered wood can take several seasons to develop. Fortunately, it is not at all difficult to accelerate the process with a little elbow grease and without harsh chemicals or expensive products. Achieving a weathered look can be particularly important if the new planks are being incorporated into an existing fence that is already weathered, but even when your fence is entirely new, a bit of weathering adds character right from the start.
Lay the raw lumber for your weathered wood fence flat, preferably in a sunny location to speed drying time. If you are working on a wooden deck, protect it with a plastic tarp. Lawns and most other surfaces need no such protection.
Prepare a solution consisting of one part baking soda to five parts warm water. Stir thoroughly until all of the baking soda has dissolved. How much solution you prepare depends on the size of your project.
Apply the mixture to the fencing material using a soaked rag or a paintbrush. Turn the boards and apply the mixture to the back side and board edges as well. Allow the mixture to remain on the boards overnight and then rinse with a hose. Prop the wet lumber against a wall or other support to allow it to air-dry on all sides for 24 hours.
Repeat the entire process one or more times until you have achieved the desired results, remembering that damp wood will appear darker and warmer in color than dry wood.