DIY Painting Trim Molding

Painting a nice, straight line on trim molding or along a ceiling is known as "cutting–in" by professional painters. In this article we offer two methods of using masking tape to form a straight cut–in line between walls and trim molding. Both work well so choose the one that suits your situation. See this link for help painting a straight line between walls and ceiling.

Painting Walls First

Before you begin make sure your trim is primed with a color close to the finish color. If your trim is not primed or the color is very different from the color you are painting, apply a first coat before proceeding. This will make it possible to cover the trim with one finish coat and make the whole job go easier.

If you're painting the trim using alkyd or oil paint, let it dry for 12 to 24 hours and lightly sand before proceeding. If you're using latex paint, let it dry according to the label instructions but don't sand between coats.

Paint the Walls

When the first coat on the trim is dry, paint the walls. Start by brushing a band of paint, a couple inches wide, along the trim letting it overlap onto the molding. Avoid getting gobs of paint on the trim but be sure to completely cover the seam between the molding and the wall. Follow with the roller work. Do as many coats as needed to get good coverage on the walls and let the final coat dry for about a week before attempting to tape.

Tape the Walls

Use delicate masking tape to form a straight line on the wall surface as close to the trim as possible without sticking the tape to the molding itself. Use several short lengths of tape if necessary to control exactly where it sticks. Overlap the ends of each piece a bit.

Paint the Trim

Load the brush lightly with a quality latex or alkyd paint and apply a thin coat overlapping the tape slightly. To prevent bleeding under the tape use a light brush to leave only a thin coat along the seam. Work along one wall at a time and remove the tape right away.

Pull the Tape

Pull the masking tape off as soon as possible and before the paint can dry. This will minimize the chance of pulling the new paint off with the tape. Pull slowly and watch for peeling. If necessary run the point of a putty knife along the edge of the tape to break any paint film.

Painting the trim before masking to do the walls can be a bit more difficult when painting baseboards than the other way around. This is mainly because the top of a baseboard molding only has a very narrow surface where it meets the wall. Taping this small strip and getting a straight line can be a bit tricky.

Trim moldings with a thicker edge like casings and chair rails will be much easier to tape but in addition to baseboards, crown moldings, picture rails and other small profiles will require close attention to get a crisp line between paint colors.

Paint the Trim

Brush paint on the trim overlapping onto the wall slightly but avoid leaving a very thick coat in the seam between the wall and molding. If your trim paint will take two or more coats to cover do as many as necessary and let the final coat dry completely before taping. If you're using an oil paint it should dry sufficiently overnight, if you're using latex let it dry for about a week.

Tape the Trim

Mask the trim using several short strips of tape and overlapping the ends of each new piece. Press the tape tightly to the trim using a clean putty knife, pushing down while pulling it along. Make sure the tape is flat with no bubbles or gaps between it and the molding.

Paint the Walls

If you need to do more than one coat for good coverage on the walls, brush near the trim but avoid touching the tape as much as possible until applying the last coat. On the final coat, paint along the trim using a lightly filled brush and overlapping the tape slightly. Avoid applying excess paint that would bleed under but be sure to completely cover the seam.

Pull the Tape

Pull the tape slowly and watch for peeling. To minimize the chance of pulling the paint off with the masking tape, it's a good idea to do the final coat on one wall at a time so you can remove the tape before the paint can dry. This is especially true if you're using a shiny paint. If the paint starts to come away with the tape, run the point of a putty knife lightly along the edge to break any paint film.