Pressure treating lumber with preservatives prevents the wood from rot and decay caused by fungi, termites or microorganisms. Building codes often call for pressure-treated wood when it comes into direct contact or within inches of exposed soil. Lumber is stamped at the mill according to its grade. An American Lumber Standard Committee (ALSC) grade mark and an American Wood-Preservers' Association (AWPA) tag certify the lumber's quality. Before painting or staining the wood, any visible stamps must be removed.
Add a small amount of soap to a piece of steel wool unless it already comes preloaded with soap. Scrub the ink on the stamp until it is gone. Rinse with clean water. Move on to baking soda if any ink remains.
Make a paste of 3 tsp. baking soda and 1 tsp. water in a bowl. If too dry, add more water, a small amount at a time. Use an old toothbrush to rub the paste onto the ink stamp. Scrub the stamp well. Allow the paste to stand for about 10 minutes and then dampen a sponge with warm water to wash it away.
Spread rubbing alcohol over the affected area using a rag to remove any residue left by the baking soda-water paste. Try the paint thinner method in step 4 if the ink remains.
Rub the ink stamp with a sponge dampened with paint thinner. Prepare to sand away any ink that still shows.
Use an electric hand sander with fine-grit sandpaper to remove the stamp. Sand in the same direction as the wood grain. Continue sanding until the stamp disappears. Sand lightly around the spot to smooth and even the wood as much as possible.