How to Polyurethane Over Water Based Paint
- 1). Wash exterior painted finishes, using a pressure washer. Intense water pressure may strip the paint. Avoid this by using a low-pressure, wide-angle spray tip. Rinse interior painted finishes, using wet rags. Let the painted surface dry for four hours.
- 2). Wipe down the painted finish, using tack cloths.
- 3). Cover surfaces adjacent to the painted finish, using a low-tack tape. Spread drop cloths out beneath the finished surface.
- 4). Open the can of polyurethane, then stir the clear finish, using a wooden stirring stick.
- 5). Apply the polyurethane to the painted finish, using a 2- to 3-inch polyester paintbrush. Brush left to right, applying gentle pressure as you move your paintbrush.
- 6). Look closely at the polyurethane finish to see if it is sagging. Quickly smooth these types of flaws before they have a chance to fully dry. Let the polyurethane dry for two hours.
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