How to Paint Window Trim Like a Pro

Trimwork acts as the frame for your room's view, and when it is scuffed or yellowed, it drags down the entire aesthetic of a bedroom. Achieving a professional finish isn't about expensive brushes, but rather the patience to prep the surface so the paint has a fighting chance to bond. A clean, smooth, and properly primed surface is the difference between a amateurish glob of paint and a factory-smooth edge that holds up to years of sunlight and window operation. When you approach this project, visualize the finish before you open the can. Professional results require keeping the glass pristine and the lines razor-sharp. You are looking for a finish that is hard, uniform, and free of brush marks. If you rush the prep, you will see it in every glint of afternoon light; if you invest the time to sand and mask, the result will look like it was installed yesterday.

  1. Remove All Grime First. Wipe down all trim with a solution of trisodium phosphate or a degreaser to remove years of dust, finger oils, and grime. Rinse with a damp cloth and let it dry completely before proceeding.
  2. Scuff for Paint Grip. Use 120-grit sandpaper to scuff the existing finish, which removes minor imperfections and creates a profile for the new paint. Follow up with a tack cloth to remove all sanding dust.
  3. Seal Glass Edges Tight. Apply painter's tape along the edge of the glass where it meets the wood. Press the edge of the tape down firmly with a plastic putty knife to seal it and prevent paint bleed.
  4. Seal All Cracks Clean. Apply a bead of paintable acrylic latex caulk to any cracks between the trim and the drywall. Smooth the bead with a damp finger and allow it to dry before painting.
  5. Prime for Flawless Finish. Use a high-quality bonding primer, especially if you are changing colors or painting over glossy surfaces. Apply a thin, even coat using a synthetic sash brush.
  6. Execute Razor-Sharp Lines. Apply two coats of semi-gloss or satin enamel paint. Use long, smooth brush strokes and avoid overworking the paint to prevent visible brush marks.