Q: If it rains within 24 hours after I coat my deck, what will happen to the finish?
A: In general, rain will not significantly degrade a new coating. Water-base coatings, especially, will dry within a few hours and will have sufficient water repellency to weather some rainfall. Oil-base finishes take longer to dry, so check the local weather forecast before scheduling the project.
If an unexpected shower occurs, the coating may take longer to dry or the color may be affected. Long term effects may include diminished protection, such as premature graying or reduced water repellency. If the color appears to be uneven or if there are water spots, a thin coat may be re-applied to the affected areas. Be sure to brush this thin coat vigorously into the wood pores.