Sanding smooths the surface by working through progressively finer abrasives, typically progressing 80, 120, 150, 180, and 220 grit for most furniture. The rule of skipping no more than one grit ensures that each step removes the scratches left by the previous one. Sanding sealer and pre-stain conditioner reduce splotchy absorption on blotch-prone woods like pine, evening out how the surface takes color.
Wood finishes protect the surface and enhance appearance, and they fall into several families. Drying oils penetrate and harden within the wood: tung oil is a classic choice, while linseed oil is less protective. Boiled linseed oil (BLO) dries faster than raw, but oily rags are a genuine fire hazard because they can spontaneously combust, so they should be spread out to dry or submerged in water. Shellac, a traditional finish made from lac bug secretions, is reversible with alcohol and is used for sealing, French polishing, and food-safe protection. Lacquer is a solvent-based finish that dries to a durable, clear film. Polyurethane is a tough, plastic-like coating, with oil-based versions that amber over time and water-based versions that stay clear. A wipe-on finish, made by thinning varnish and applying it with a rag, is user-friendly and forgiving. Multiple thin coats, lightly sanded between applications, adhere better and look better than a single thick coat. Wax, applied as a top coat or a standalone finish, gives a soft, low-protection sheen.
Always test a finish on a scrap board before committing to the final piece. Wood filler hides holes, dents, and gaps, with solvent-based fillers accepting stain and water-based fillers being easier to work; for permanent fills, epoxy is more stable over time than wood filler. Staining adds color while enhancing grain, and stains are either dye, which penetrates into the wood, or pigment, which sits on the surface. Standard preparation is to sand to 180 or 220 grit, dust off, and apply a conditioner if needed; wiping off excess stain evens the color, and a longer dwell time produces a darker result. Pre-finishing, or finishing parts before assembly, makes it easier to reach every surface, while rub-out polishing refines a cured finish to a consistent sheen. When defects appear, sanding back and re-coating is the typical remedy.