Applying a sealer or topcoat after staining wood is highly recommended, though not always strictly required. A sealer protects the wood from moisture, UV rays, and weather-related issues, which is especially important for outdoor surfaces like decks and fences. It also enhances the stain's durability, prevents fading over time, and gives the wood a cleaner, more professional-looking finish. For some indoor applications, a sealer may not be necessary, depending on the type of stain used and the level of protection needed. It's always best to check the stain manufacturer's recommendations and consider the wood's intended use and exposure when deciding whether to apply a sealer.

Yes, it is important to wash your deck before painting to ensure the paint applies well and adheres properly. While you don't have to use a pressure washer, it is one of the most efficient cleaning methods. Pressure washing can quickly remove dirt, wood fibers, and flaked paint, getting deeper into the wood than manual scrubbing. You can also clean the deck with a stiff broom and a cleaning solution. Regardless of the method, a clean surface is essential for good paint adhesion. Make sure the deck is completely dry before applying any paint.

It’s necessary for paint to completely dry before exposure to rain, and that drying time varies by the type of paint used. Oil-based paint takes 6 to 8 hours to dry on average, meaning that’s the minimum time needed between the last brush stroke and the first raindrop. Latex paint dries faster at around 1 hour, and acrylic paint is even quicker, usually drying in about 30 minutes. If rain is in the forecast, check the paint manufacturer's details before laying on a new coat. 

Staining a deck with a rag is typically a better option than using a brush, as it helps the stain penetrate deeper into the wood. However, both brushes and rags are best reserved for detailed work because using these tools on an entire deck can require tediously crawling around on your hands and knees. A pad applicator, sprayer, or roller are preferred alternatives to applying stain over the majority of a deck. Use a rag for railings and other detailed work, and let the wood soak up as much of the stain as possible before wiping away drips or pools.