How to Paint Over a Polyurethane Finish

Written by ryan lawrence
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How to Paint Over a Polyurethane Finish
Sand the polyurethane finish. (Stockbyte/Stockbyte/Getty Images)

When amateur painters try to paint over a surfaces treated with a polyurethane finish, flaking often occurs. Polyurethane is a waterproof sealant that protects surfaces from moisture. Unfortunately, its waterproof characteristics also leave polyurethane ill-suited for paint. In addition, because polyurethane finishes are oil-based, they will reject water-based latex finishes. Combat this by treating the polyurethane with a special oil primer, specifically formulated to work with latex topcoats.

Skill level:

Things you need

  • Water-based soap
  • Sponge
  • Rags
  • Sandpaper
  • Oil-based primer
  • 2- to 4-inch natural-bristled paintbrush
  • White spirit
  • Latex paint
  • 2- to 4-inch polyester paintbrush

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  1. 1

    Wash the polyurethane finish with water-based soap, using a sponge. Rinse the finish with wet rags. Allow 24 hours of dry time.

  2. 2

    Sand the polyurethane finish until it appears dull.

  3. 3

    Coat the polyurethane finish with the oil-based primer that is compatible with water-based topcoats, using a two-to-four inch natural-bristled brush. Wait two hours for the oil primer to dry.

  4. 4

    Clean the brush with white spirit. Don't use tap water, as this will destroy the brush.

  5. 5

    Coat the primed polyurethane finish with latex paint, using a two-to-four inch polyester brush. Wait two hours for the finish coat to dry.

  6. 6

    Use water to clean the brush. Don't use white spirit, as this will destroy the brush.

Tips and warnings

  • Kilz makes an oil primer that is compatible with latex paint.
  • Most oil-based primers will reject latex paint. Study the labelling to make sure that the primer you select will work with latex topcoats.
  • Do not paint over an unprimed polyurethane finish, or peeling will result.
  • Do not prime an unsanded polyurethane finish, or flaking will result.

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