How to Recoat Polyurethane

Polyurethane is a synthetic resin of plastic material that is joined together by urethane and can be rigid or flexible in nature.

Polyurethane Coating without Wax Finish

The shiny polyurethane coating on hardwood floors needs to be recoated every 5 to 7 years.The shiny polyurethane coating on hardwood floors needs to be recoated every 5 to 7 years.
This material is typically used in paints and varnishes and is the shiny material used to coat hardwood floors to provide a layer of protection. It is also used in toys, appliances and sometimes used as a replacement for rubber. Polyurethane must be re-coated every five to seven years on hardwood floors to fix the appearance of scuff marks and scratches.

Test a small inconspicuous area of the polyurethane coated floor for a wax finish if you are unsure if it contains wax. For example, test an area in a corner of the inside of a closet or near the corner of a room. Sand the area with 120-grit sandpaper and wipe dust particles away with a damp cloth. Add a thin coat of polyurethane with a paintbrush and allow it to dry for up to four hours. If the test area is smooth and shiny, it does not contain wax.

Lightly sand the entire floor with a heavy floor buffer to remove the scuffs and scratches from the existing coating. Vacuum up the dust particles and clean the floor with a mop a damp lint-free cloth. Wait for the floor to dry prior to applying the polyurethane coating.

Add a thin layer of oil based or water-based polyurethane coating to the floor with a lambswool applicator pad secured to the bottom of a mop handle. Water-based coating dry faster -- about four hours per layer -- compared to about 24 hours for oil based coats. Use a paint brush to reach into the corners and edges. Apply as many coats as you like, but there should be a minimum of two. Lightly sand in between coats with 80-grit sandpaper. Wait for the polyurethane to dry before applying each coat.

Polyurethane Coating with Wax Finish

Test a small inconspicuous area of the polyurethane coated floor for a wax finish if you are unsure if it contains wax. For example, test an area in a corner of the inside of a closet or near the corner of a room. Sand the area with 120-grit sandpaper and wipe dust particles away with a damp cloth. Add a thin coat of polyurethane with a paintbrush and allow it to dry for up to four hours. If the test area is dull and free of shine, rippled or flaky, most likely it contains wax and the polyurethane coating must be completely removed down to the wood with a rotary floor sander before continuing. This machine can be rented from a home improvement store.

Sand the entire floor you wish to coat with the rotary sander. If you cannot reach the edges with the machine, sand them by hand.

Vacuum up the dust and mop the floors with a damp cloth. Wait for the floors to completely dry before applying the polyurethane finish. The polyurethane will not be able to adhere to the wax, so it must all be removed.

Add a thin layer of oil based or water-based polyurethane coating to the floor with a lambswool applicator pad secured to the bottom of a mop handle. There must be at least two coats of polyurethane, but add as many as you like. Use a paint brush to reach into the corners and edges. Lightly sand in between coats with 80-grit sandpaper. Allow it to dry up to four hours in between coats.

Things You Will Need

  • 120-grit sandpaper
  • Vacuum
  • Lint-free cloth
  • Mop (optional)
  • Heavy floor buffer
  • Polyurethane
  • Paint brush
  • Lambswool applicator pad
  • 80-grit sandpaper
  • Rotary floor sander

Warning

  • Make sure you have adequate ventilation when using oil-based polyurethane, since the fumes can be toxic.

About the Author

Dianne Christensen began writing professionally in 2003 for the "Muskegon Chronicle" in Muskegon, Mich. She has a Bachelor of Science in journalism from Grand Valley State University in Allendale, Mich.