Water repellents and water sealers work by coating wood surfaces with a protective finish that seals out and repels water. This is important to keep wood from absorbing water and swelling, shrinking, buckling, warping, and cracking. Many people think that the wood they purchase already has been water sealed, but frequently that is not the case. Others think that they should wait a season or two before protecting their wood, but that’s not necessary. In fact, exterior wood surfaces should be protected immediately after the construction project is completed. Morning dew, rainwater and melting ice or snow are quickly absorbed by unprotected wood, causing it to soften and swell. Direct exposure to the sun's heat causes drying, which makes wood shrink.
To apply a water repellent/water sealer, first clean the deck or other wood to remove surface barriers and expose the wood itself. Then you are ready to protect it with the water repellent/sealer. There are many to choose from including Wolman products that contain a mildewcide to impede mildew growth on the coating film.
WOLMAN also offers RainCoat Tinted Water Repellent, a pigmented water sealer that adds UV protection in a sheer, wood-colored matte finish