Untreated lumber, exposed to the elements and moisture, is at risk of weathering and rotting over time. Lumber that has been factory pre-treated is the best to use for outdoor furniture and other exterior projects. However, if you already have an item made of untreated lumber that is left outdoors, you can treat it yourself to seal out any moisture and ensure that it holds up well for years to come.
Inspect your untreated lumber for mold or wood rot. If none appears, the wood can be dried and then treated with sealant.
Wash off the wood with a wet towel. Soak up as much water as you can with a dry towel.
Allow the wood to sit and air dry while keeping it protected from the weather and providing proper air circulation.
Avoid using fans, air conditioners or heaters to aid in the drying process. Slow drying is best for wood with moisture.
Allow the wood to dry completely, or at least three days.
Apply a coat of wood sealant over the surface of the untreated wood, using a paint brush, to prevent moisture from penetrating the wood. Make brush strokes from one end of the board to the other, to prevent lap marks.
Let the first coat of wood sealant dry before applying a second coat. Allow the first coat to dry completely for best results.