Flat paint creates a powdery matte finish on your wall, which hides imperfections in the wall surface better than eggshell or shiny semi-gloss finishes. Use flat paint for bold colors like red and royal blue to tone down the brightness and create a warmer, more soothing environment. Flat paint is less likely to show roller and brush marks but you still need to use the proper painting techniques to achieve the perfect matte finish.
Use painter's tape to frame the wall surfaces to be painted, creating a barrier between the wall and the baseboards, door and window trim.
Cover the floor and any remaining furniture with drop cloths to protect the surfaces from paint spray.
Paint one wall at a time. Use a 2- to 3-inch wide-angled brush to cut in along the ceiling line. Dip the brush into the paint, about 1/2 way up the bristles. Do not overload the paint brush. Tap the brush handle on the edge of the paint cam rim to shake off excess paint. Drag the tips of the bristles lightly across the edge of the rim if necessary.
Place the edge of the bristles approximately 1/4 inch from the top of the wall and gently fan the bristles out until they reach the edge. At the same time, gently slide the brush steadily along the ceiling line. The goal is to create as straight a line as possible between the wall and ceiling color.
Cut in around the window and door trim next, using the same technique. The painter's tape will catch excess paint, so you don't have to focus as much on creating the perfect edge. Finish by cutting in at the baseboard.
Roller the main wall, while the brushed-on paint is still wet. This helps the paint blend together and reduces overlap marks. If you're using the flat paint to hide wall imperfections, the Hometime website recommends a roller with a 3/8 inch nap. The heavier the nap, the more paint it will hold in order to fill any holes or small cracks in the surface. Consider a 1/2-inch nap for older, rough and uneven walls.
Keep the roller wet all the way around, but not dripping with paint. Roller from the top of the wall down. Start with straight up and down strokes, then work into a "W" pattern to help even out the paint and reduce roller marks.
Roller over as many of the brush strokes at the ceiling and trim lines as you can, as the roller creates a more even finish. The Bob Vila website recommends not overspreading flat paint, however. It has a tendency to lift off the wall again if the roller hits it too many times.
Move to the next wall and repeat the process, until the room is fully painted.
Evaluate the wall in sunlight or with a strong shop light, when the paint is completely dry. A one-coat wall is possible with a pale flat paint, but darker colors and rougher walls typically require a second coat.