How to Paint Window Sills Without Streaks

There are plenty of tutorials available for painting walls and ceilings, but how to paint trim and window sills is something often omitted.

Adding a new coat of primer and paint will change up the color and freshen a tired window.

It’s as simple as:

  • Clean the area
  • Sand off old paint
  • Fill holes and dents, if necessary
  • Prime
  • Paint with the desired color

Gather together all materials listed below before starting your project and wear clothing you won’t mind getting paint on. Painting window sills and trim isn’t a big project like painting walls, but you run the risk of drips and spills any time you’re working with paint.


  • Dropcloth for the floor
  • Cloths and soapy water for cleaning
  • Painter’s tape
  • Trim brush
  • Paint and primer – use a premium interior enamel paint and suitable primer
  • Sandpaper – Choose 120-180 grit
  • Wood filler and caulking, if necessary.

A Note for Older Homes

If your home was built before 1979 and hasn’t been repainted, there is a good chance there may be lead in the paint.

Consult your local health authority or the US Environmental Protection Agency website for guidelines on testing the paint for lead and what precautions to take before sanding and painting.

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Materials required to Paint Window Sills without Streaks


A Complete Guide for Painting Window Sills and Trim

Spread the drop cloth out on the floor.

Prepare the area that will be painted by cleaning the window sill and trim, so it’s free of dirt, cobwebs, and dust. Attention to detail during the preparation stages of painting can help ensure a smooth and even layer of paint.

Prepare the Window Sill and Trim for Painting

  1. Occasionally, window sills may also need the paint completely stripped off, right down to the wood. However, you can just and most and remove the outer layers of paint.
  2. With wood filler or caulk, repair any damaged wood or areas with holes or dents. Once the filler is dry, sand the air for a smooth surface to paint.
  3. Use the painter’s tape to tape around the sill, trim, and windows to ensure clean lines and avoid getting paint where you don’t want it to go, like the wall and the panes of glass.

Priming and Painting

  1. Spot treat discolored areas with primer. These are areas that have been drawn on, or you had to sand or fill in. This spot treating helps even out the coats of primer later.
  2. Apply primer to the entire area using thin coats, thoroughly cover the area while avoiding drips and brushstrokes wherever possible.
  3. Although you don’t need to be super careful about putting on the primer, it is the foundation and base coat for your colored paint, so take your time and give it plenty of time to dry before adding more layers.
  4. Once the primer is completely dry, sand the area with a high 120 grit sandpaper to remove imperfections and streaks. Choose a ‘no load’ sandpaper if possible to help avoid clogging.
  5. The key to painting a window sill without streaks is a glossy and blemish-free foundation for the colored paint to sit on top of. When the primer coat looks good, then begin applying the colored paint.
  6. Choose an oil-based or water-based paint. Adding a latex conditioner to water-based paint will help you receive more of the benefits of oil-based like better adhesion, slower drying time, and fewer brush strokes without the environmental disposal issues.
  7. Paint with your chosen paint. Consult the chart below if you’re unsure whether to go with oil or water-based paint.
  8. Let the paint dry completely.
  9. Remove painter’s tape carefully from completely dry paint.
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Paint Comparison (Oil-based vs. Water-based)


Oil-based Water-based
Benefits ●     Allows for a longer time between brush strokes

●     Better adhesion and durability

●     Suitable for chalky and rough surfaces

●     Requires fewer brush strokes

●     Environmental friendly

●     Washes off skin with soap and water

●     More versatile

●     Safer handling

A Complete Guide for Painting Window Sills and Trim

Painting Technique Tips to Reduce Streaks

  • Hold the brush at an angle and sweep on the paint. Painting at an angle and letting the weight of the paint level itself should help eliminate brush strokes.
  • Cut in first, and then paint in the middle. Cutting in means the first stroke should go close to the edge and then use the second stroke to smooth along the edge of the paint for a nice clean line. Use that technique around the outside and then paint in the middle using as few brush strokes as possible.
  • Work quickly and don’t overwork any one area. Load the brush with paint and then unload it on the window sill quickly in short strokes that you can then go over with another side of the brush to even the paint out.
  • Always start a stroke on an unpainted area to avoid doubling the paint up in one spot.
  • Don’t brush over the edge of the window sill or trim. Align the edge of the bristles with the edge of the sill to help prevent drips or run-off.

Frequently Asked Questions

Here are some frequently asked questions about how to paint trim.

Will streaks go away when the paint dries?

While thinner streaks may disappear once the paint dries, there’s a good chance that the lines you see in wet paint will be there when it dries, too. That’s why it’s essential to do the work to prevent them in the first place.

When painting, do you paint the trim first?

After taping everything, it’s easier to paint the trim first and do all the cutting in before working on larger sections.

Should you paint trim with a brush or roller?

You should only use a roller on large areas like the middle of a window sill. You may find it unnecessary when working in small areas like the window sill and trim.

How do I get a smooth finish on my trim?

The Wrap Up

Painting window sills and trim without streaks doesn’t have to be complicated. It just requires a little bit of extra work to prepare the area before painting begins.

The whole process boils down to five broad areas: clean it, sand it, fill in holes, prime, and then paint. Without those tips and a bit of time, you can transform a tired-looking window into one that looks like new again.

Happy painting!

The wrap up for Painting window sills and trim without streaks