Close the mirrored sliding closet door, if it is open, and place one or more pieces of plastic sheeting or drop cloths underneath and next to the door. Wipe the door frame with a soft cloth or rag to remove any loose dust and debris. Wear latex gloves to keep your hands clean.
Sand the door frame lightly with a piece of 120-grit sandpaper to remove any scratches and caked-on debris. Use a 120-grit sanding sponge for areas the sandpaper cannot reach. Wipe the door frame again with the soft cloth or rag to remove any sanding residue.
Fill a bucket with 1/2 cup of mild detergent and 1/2 gallon of warm water. Stir the soap mixture with a clean, soft cloth or rag and wring out excess mixture.
Wipe the door frame thoroughly, including around the door knob and hinges, with the mixture-soaked cloth or rag to remove any dust, dirt and debris. Rinse out the cloth or rag under warm, running water and wring out the excess. Wipe the door frame again to remove any soap residue. Dry the door frame with a clean, soft cloth or rag.
Place one or two strips of painter’s tape or masking tape along the mirror’s outer edge and any areas of the door frame you don‘t want to paint. The tape should not overlap onto the frame.
Use a Phillips or flat screwdriver to loosen the closet’s door knob, if one is present, so you can paint under the knob and its metal plate.
Fill a paint tray with latex or similar paint. Place a small paint roller in the paint, roll off the excess and start rolling paint onto one section of the door frame. Roll slowly to keep the paint from splashing.
Use a paintbrush to apply paint to areas the roller cannot access. Open your closet door to paint the door frame’s inner areas.
Aim a box fan toward the closet door and turn it on to speed up the paint drying process. Repeat Steps 2 and 3 to apply a second coat of paint on the frame.