Wood that has been exposed to the elements on the side of a barn undergoes a natural chemical reaction that is triggered by the ultraviolet spectrum of the sun's rays. The result is a beautiful rough-grained wood that can add interest to your interior design as decorative molding, wainscoting, or cabinet material.
Preserving the Wood
Set up the wood on the saw horses outside. It's important that you don't bring the wood inside a building at this point.
Inspect every board for insect damage. Look especially at the back of each board (the side that was facing indoors), where there might be cavities containing insects.
Cut away any portion of the wood that's infected.
Clean the surface of the boards with the wire brush and the polyester cleaning brush. It is usually not necessary to wash the boards, just use these cleaning tools to remove as much of the dirt and dust as you can. If you do wash them, use a mild soapy solution and be sure to rinse thoroughly.
Apply a coat of polyurethane to the front surface and all sides of each board. The natural weathering process has already made the boards somewhat resistant to decay, so one coat should be enough to preserve the appearance of the board.
Let the polyurethane dry and take your wood inside. If you are cutting the boards, you may have to stain the cut and/or coat it with the polyurethane to match the weathered portion of the board.