Do You Ever Use Wet Sandpaper in Finishing Wood?

Wet/Dry Sandpaper

• Wet sanding requires a black silicon-carbide sandpaper with a waterproof backing. Silicon-carbide is the hardest type of sandpaper; for wet sanding, finishers generally use 320- to 600-grit sandpapers. However, an extremely fine finish may require 800- to 2,000-grit paper.

Sanding Between Finish Coats

• Wood finishers usually wet-sand gently between coats of varnish to remove flaws such as brush marks, dust and drips. Typically, the sandpaper is wrapped around a rubber or cork sanding block and dipped in water containing a drop or two of liquid detergent. While sanding, it’s important to rinse the sandpaper often and keep the wood well-lubricated. Once the flaws are gone, the wood is wiped clean and allowed to dry completely, at which point it’s ready for the next coat of varnish. For the smoothest finish, this process is repeated between each coat with increasingly fine grades of sandpaper.

Wet Sanding With Oil

• Some woodworkers use wet/dry sandpaper with a finishing oil instead of water. This produces a thick slurry of oil and wood dust that penetrates and seals the wood’s pores, resulting in a superior finish. As with water sanding, it’s essential to keep the sandpaper well-lubricated, and the process is usually repeated at least once to achieve a higher gloss.

Common Applications

• Although it’s most often used to finish or restore fine modern and vintage furniture, wet sanding is also a common method of imparting a uniform, mirror-like gloss to gun stocks, strip-planked boats and wood-bodied string instruments like guitars, mandolins, violins and pianos.