How to Sand & Stain an Unfinished Door

Set the door on top of a clean work space or a pair of sawhorses. Sand down all surfaces of the door with a hand-held power sander fitted with a medium-grade sandpaper. For any areas that cannot be reached with the power sander, sand by hand with a piece of sandpaper or a sanding sponge.

Wipe down the entire surface of the door with a tack cloth. This will remove the dust created during the sanding process.

Stain the door with a stain of your choice. Stains can be applied with brushes, rags, rollers or sprayers -- use the tool with which you are most comfortable and familiar. Once the door is evenly coated with stain, use a clean, dry cloth to wipe the door until no more stain comes off on the cloth. When staining and wiping, always move your tool with the grain of the wood.

Allow the door to dry completely. The wait time varies by product and can be affected by weather conditions, so read the manufacturer's label for specific information.

Apply a protective topcoat to the stained side of the door. Polyurethane is a common option for doors and floors -- woodworking projects that get a lot of traffic or see heavy use -- because of its durability. Paint the polyurethane onto the door with a foam applicator brush and allow it to dry completely.

Lightly sand the polyurethane with 400-grit sandpaper to get rid of any bubbles that may have occurred during the drying process -- this is common with the first coat of polyurethane. Wipe away any dust with a tack cloth and paint on another coat of polyurethane.

Allow the second coat of polyurethane to dry completely. When it has, flip the door over so you can stain and seal the other side of the door. Allow the door to dry before installing any hardware.