In some cases ProWood treated lumber has water repellent already applied during the pressure-treating process. Make sure to read and understand the end tag on your new lumber to determine whether a factory-applied water repellent has been added. The information on the treated lumber tag or end tag will help you understand when to apply a topical wood sealer.
Stain or Seal Dry Wood – The time it takes for wood to dry out depends on the climate and the wood's exposure to the sun. During summer, pressure-treated lumber under full sun can dry in a few days. In cool, damp weather or when shaded, wood will take much longer to dry.
Use the water test to see if it's time to seal (or re-seal). Drizzle some water onto the wood. If the water beads, the wood is still sealed and protected. If the water is quickly absorbed into the wood, it's time to apply a sealer. Test a few different areas of the surface. Note: High-traffic spots on a wood deck are likely to wear down before corners and railing balusters.
Seal Kiln Dried Lumber – In some areas you can buy treated wood that is Kiln Dried After Treatment (KDAT). With KDAT lumber, moisture is removed from the wood before shipment to a lumberyard. KDAT will be marked on each piece of wood with an end tag or an ink stamp. It is recommended that you seal KDAT lumber immediately unless it has been pressure-treated with a water repellent additive.
Add Color and Water Repellency with a Wood Sealer – Start by applying a topical sealant to your new project for surface protection. We do not recommend using a conventional multi-coat paint system or varnish. The performance is nearly always disappointing, and scraping and sanding often must precede repainting. Instead, choose an outdoor wood sealer. A wood sealer offers a degree of water repellency and color to treated lumber without forming a thick coating on the surface. It will also allow any remaining moisture to slowly leave wood after the coating has been applied.
Wood sealers come in three versions; solid stains, semi-transparent and clear:
- Solid Stains – It is recommended that "solid" wood sealers, which have more pigment, be used only on vertical projects such as fences and siding. If used on decking, weather and foot traffic will wear through the pigment unevenly.
- Semi-transparent Sealants – This type of wood sealant is suitable for vertical or horizontal surfaces such as deck boards, rails, siding and playground equipment. There are several brands available in many colors.
- Clear Sealants – This type of sealant has no pigment or color. It still offers some protection from the weather, although wood fading will occur more rapidly than color with sealants. Eventually, the wood will fade to gray, which may or may not be the look you desire.
NOTE: We recommend using wood sealers that contain an ultraviolet stabilizer. The stabilizer will not prevent eventual discoloration to a weathered gray appearance, but it will slow the process down. Whatever sealant you choose, follow the manufacturer's instructions carefully.