Remove all furniture and objects from the deck.
Brush off debris with a broom.
Spray down the deck with a garden hose to wet it.
Cover any surrounding plants near the deck with protective sheets.
Combine commercial deck cleaner and water in the ratio described on the packaging instructions, then spray it evenly onto the deck's surface with a garden sprayer.
Rinse the cleaner off the deck with a garden hose after it has set for 15 minutes. Scrub any tough stains with a nylon brush. Allow the porch to dry for at least 48 hours before continuing.
Fill a clean garden sprayer with deck sealant intended specifically for use on mahogany wood.
Spray the sealant onto the deck in long, sweeping strokes. Allow it to dry for 24 hours, then apply a second coat. Wait at least 24 hours before returning furniture and using the deck.