Pressure-treated wood may be painted once it has dried. The chemicals used to protect the lumber from insects and decomposition dampen the wood. If it is painted too soon, the results are unsatisfactory.
Prior to painting press-treated wood, thoroughly scrub it with soap and water. Then rinse it and allow it to dry completely. The drying process takes weeks or, in some cases, months. When the wood feels dry, test it by dropping a few drops of water on the surface. If the droplets sink in, the wood is ready to be painted; if they bead up it is not dry enough. Pressure-treated lumber that is labeled kiln-dried after treatment, or KDAT, dries more quickly.