Check your local weather forecast for likelihood of rain. You need to seal your Garapa decking with abundant sunshine and no chance of precipitation.
Clear your Garapa deck of any furniture and outdoor grilling equipment.
Put on rubber gloves and pour 1 cup of powdered oxygen bleach into a gallon bucket of water. Mix thoroughly. Use an old broom to distribute the solution over the surface of the deck. Wait about 10 minutes for the solution to soak.
Thoroughly scrub your Garapa decking with a scrub brush, starting at the far end of the deck and working to the house. Let the wood dry out overnight or about 12 hours.
Start where the deck meets your house or the dead-end side of the deck, if no stairs to the yard are present. Pour oil-based deck sealer into a paint tray.
Apply a thin, even coat of oil-based deck sealer with a paint roller, going from the house to the steps or from the dead-end to the house, whichever is applicable.
Let the first coat of sealer dry for 24 hours or as long as directed by the manufacturer. Apply a second coat of oil-based deck sealer going in the same direction. Allow to the air dry to finish sealing your Garapa deck.