How to Apply Urethane to Spanish Cedar

Sand the Spanish cedar using extra fine-grit sandpaper and a hand or belt sander. Follow the direction of the wood grain.

Wipe the surface with a tack cloth to remove all sanding dust. A tack cloth is a sticky rag used to pick up sawdust.

Mix spar urethane with a paint stirrer. Do not shake urethane, because air bubbles will form and ruin the finish. Spar urethane blocks harmful ultraviolet rays and protects the wood from environmental changes.

Dip a natural bristle paintbrush into the spar urethane and apply a thin, even coat. Follow the wood grain and only paint in one direction. If brush strokes on the surface are noticeable, add mineral spirits to the urethane to thin the consistency by a ratio of one part mineral spirits to five parts urethane. A thinner consistency will necessitate additional coats.

Allow the spar urethane to dry completely, generally two to four hours.

Apply a second coat, following the same direction as the first coat. Apply additional coats as necessary to achieve the desired finish. Allow each coat to dry fully in-between applications.