Wood stain is not flammable after it dries. The solvent in wood stain is what causes the liquid form to be highly flammable, but the stain drying process involves the solvents dissolving, which leaves behind a non-flammable product on your wood project. Wood stain is, however, flammable before you apply it, so you should always store partially full cans and used wood stain rags away from sources of heat and open flames.

Staining or sealing a cedar deck or fence is highly recommended to extend its lifespan and protect it from the elements. While cedar is naturally resistant to mold and mildew, it is not impervious to damage from moisture, sun exposure, splintering, fading, and rot over time. Applying a protective finish creates a shield that preserves the wood's strength and appearance, potentially extending its life by five to 10 years.

When choosing a finish, it's helpful to understand the difference between a sealer and a stain. A sealer sits on top of the wood, whereas a combination stain and sealer soaks into the top layer. Because it penetrates the wood, a stain generally offers better protection against UV damage and rot and lasts significantly longer. For the best results that also preserve the wood's natural color, consider using a near-translucent stain.

To maintain protection, plan on reapplying the stain or sealer every two to three years, either as a DIY project or by hiring a professional.

The best way to protect a deck is to prevent damage from UV light, water, mold, mildew, insects, and abrasive cleaning methods. Sweep regularly to prevent debris that hides bugs and traps moisture that can result in mold or mildew growth. Use a deck cleaner once a year to remove algae, mold, and mildew. Avoid using pressure washers on high, as they can damage the wood. Applying a deck sealant can protect the wood from UV and water damage, and adding shade can also reduce sunlight damage.

Stains penetrate wood best when it's cool and dry, so you want to avoid moisture. If the wood is wet upon application, or if it rains before the stain dries, the water will soak into the wood and displace the staining solution. This leads to a flaky and blotchy look, which is the opposite of a sumptuous even coat. Once the stain has fully cured, after about 3 days, rain shouldn’t cause you any problems.