Vinyl trim on exterior windows must be cleaned, sanded and primed before applying paint. Tools needed include bleach, a bucket, gloves, protective eyewear, 220-grit sandpaper, painter's tape, a paint bucket, a paint brush, exterior latex primer and exterior latex paint.
Clean the trim
Prepare a mixture of 3 parts water to 1 part bleach. Wearing rubber gloves and protective eyewear, clean the vinyl trim with the bleach mixture, removing dirt, mold and mildew. Stubborn dirt should be scrubbed with a brush until the trim is clean.
Sand the trim
Using 220-grit sandpaper, lightly sand the trim to provide a textured surface to which the paint can adhere. Wash the trim with clear water to remove any dust, and allow it to dry.
Mask the trim with painter's tape
Tape around the inside and outside edges of the trim with blue painter's tape. Smooth the edges of the tape, making sure the corners are crisp.
Paint the trim
Apply a coat of latex exterior primer to the trim. Allow the primer to dry according to the manufacturer's instructions. Apply the exterior latex paint over the primer, using only enough coats to cover it. Carefully remove the painter's tape, and allow the paint to dry.