Polyurethane for wood gives a high-gloss, durable finish. Polyurethane is offered in both oil-based and water-based formulas. Oil-based polyurethanes are resistant to alcohol, water and acids. On the other hand, the oil-based product turns yellow as it ages. Water-based polyurethane goes on clear and stays clear, however it is not resistant to acids and alcohol. Water-based finishes will also be softer than regular finishes. While either polyurethane finish gives years of good service with proper maintenance, it sometimes becomes necessary or desirable to remove this wood finish. This task is accomplished via the utilization of chemical paint and varnish removers and light sanding.
Assemble equipment. Read instructions on your own substance varnish and paint stripper. Put on your protective equipment.
Apply stripper using a brush. Stripping product should be thick enough to place for about 10 minutes without drying out. Work in an area small enough to be within easy reach, when repainting flooring or other large items.
Scrape the area using a plastic scraper or plastic putty knife. Using a plastic decreases the odds of damaging the wood. Remove the softened polyurethane and stripper with soft fabrics or rags. Wash the area by wiping with a clean cloth dipped in clean water or according to the instructions on your own chemical stripper. Wipe the cleaned area with a dry cloth to prevent prolonged wetness.
Brush stripper onto an area adjacent to the place previously stripped. Allow the stripper to place for 10 minutes, then scrape and wash as before.
Sand the wood having an oscillating tool equipped with a hook and loop pad accessory fitted with 120 or 220-grit sandpaper to remove grain increased by the use of liquid. Remove sanding dust thoroughly before applying stain or new finish.