Gary Sullivan Saturday's 9am - 1pm Clean Your Deck 1. Clean your deck with soap and water before sealing. It should also be cleaned this way every couple of months after the sealer is applied. This will allow the sealer to last longer and minimize mildew and mold growth. Mildew is black spots on the surface of the wood.
Mold is green growth that accumulates on the wood.
These must not accumulate on the deck surface. After you mix PDC with water, use a stiff garage broom to swoosh it all over your deck. Let it sit for 5 minutes and rinse. PDC is also environmentally friendly and won't harm most vegetation. Once the deck dries, you are ready to seal it.