If you want your wood floors to have a weathered and old appearance, you don't have to wait 50 years for this to happen naturally. There are two main ways to make your floors appear gray. This project will typically take at least one weekend, and possibly two, depending on the amount of work required on your flooring.
Remove all the furnishings in the room, and use plastic drop cloths to seal off doors and windows. Tape over any cold air return vents or heat vents in the room. Sanding a floor is dirty work, and your whole house may end up covered in dust.
Sand the floor. Borrow or rent an orbital floor sander to save time and effort. Use a heavy-grade sandpaper for the first pass, a medium grade for the second pass and a fine grade for the third pass. This completely removes all the finish and color from the wood. You also need to sand the edges with an edge sander since the floor sander cannot reach into corners and the sides of the room.
Clean up the dust with a vacuum, and sweep up any remaining dust in the room.
Stain the floor with a gray wood stain. Several commercial companies make both oil-based or gel-based stains in a gray color. Apply one coat of this stain with either a paintbrush or a stain applicator. Let it dry. Then, sand over the entire floor by hand with a fine-grade sandpaper. Stain the flooring again. Apply a third coat if necessary.
Protect the floor. Even though your floors now look weathered, you don't want them to age before their time. Apply an oil- or water-based polyurethane to the flooring, and let it dry. Sand in between coats. Use at least two coats to protect the flooring. Use a fresh stain applicator pad to apply the poly coat.
Prepare the room. Remove all the furnishings, and tape off the floorboards.
Go over the entire floor with a medium-grade sandpaper. Then, vacuum up any dust.
Paint over the surface of the floor with a flooring primer. Once this is dry, sand over the surface lightly.
Apply a gray epoxy floor paint to the floor, and cover over the wood with at least one coat of epoxy floor paint. Use a roller or a paintbrush to paint the floor. Cut in around the edges with the brush, and then roll out the larger areas in the room. Let this dry for at least 12 hours before putting the furniture back in the room.