I recently bought a 100 year old house with original pine flooring. The contractor refinished them improperly (or with too few coats) because the finish became scratched in just a few weeks and after 6 months it looks like the finish is many years old. Can I recoat it without having to sand it? I’m afraid the floor will not be able to handle any further sanding.
Yes, you can and should recoat it. A pine floor should have at least 4 coats of an oil modified polyurethane. If you only have two, apply two more. You will have to rent a floor buffing machine, and buy a white pad and a 80 grit screen. Screen the floor until it is full of small scratches. Do the edges by hand. Run the buffer in both directions so that all of the floor is thoroughly scuffed.
Vacuum really well, then wash the floor twice with odorless mineral spirits, so no dust is left. Do it in a sweeping motion so as to draw the fine dust in the direction of exit. Let the solvent dry. Then BRUSH on a heavy coat of poly. Don’t use a lamb’s wool applicator it will cause bubbles. Let that coat dry for at least 2 days, or until when screened, it powders and scratches as before. Let it dry for 48 hours, and be aware that this finish will take 30 days to cure.