What Grit Sandpaper for Oak?

Sandpaper Grades

• Two grades of sandpaper are on the market: hobby/commercial and industrial. Home centers and hardware stores commonly stock the first type, but industrial grade sandpaper is available only through industrial supply stores. Industrial-grade sandpaper uses stronger abrasives, higher grade backing material and better glues to bond abrasives to backing. The grit on hobby sandpaper breaks down more easily and is glued to kraft paper or low-grade fabric using less moisture and heat-resistant hide glue.

Sandpaper Types

• The abrasive particles found on sandpaper may be one of five types. The least expensive, flint, is a gray material that wears down quickly and is therefore not appropriate for sanding oak. Garnet is much harder, costs more than flint, and sands oak well. Emery, a black-colored abrasive, is generally used on metal. Aluminum oxide, appropriate for sanding either wood or metal, is a reddish-colored abrasive with a sharp grip. Bluish-black silicon carbide, the hardest sandpaper type, is most commonly used for finishing metal or glass.

Classifications

• Sandpaper may also be classified according to its density. In closed-coat papers, the grit covers 100 percent of the surface but in open-coat paper, only 50 to 70 percent of the surface is covered. Closed-coat sandpaper is designed for fine finishing. For initial sanding and paint removal, open-coat paper is better because it does not clog as easily. Sandpaper adhered with hide glue are good for light- or medium-duty sanding, but waterproof resins are required for wet sanding jobs.

Fitting the Grit to the Job

• Machine sanding oak floors to remove old coatings requires an extra coarse 12- to 20-grit sandpaper. Machine sanding bare oak floors is best done using a very coarse, 24- to 36-grit paper. For paint removal, rough sanding and shaping of oak furniture, a coarse sandpaper of 40 to 50 grit is appropriate. The first sanding of an oak woodworking project requires a medium 60- to 100-grit product. For sanding between finish coats to a piece of oak, begin with 120 grit and progress through 150 to 180.