If you plan to paint your walls a darker colour than your ceiling, you have to marry the coloured wall to the ceiling without making a smudgy mess. To successfully create a clean line between the ceiling and coloured walls without getting splotches of coloured paint on the ceiling, take your time painting small areas of the wall near the ceiling. Although the technique may seem tedious (but worth it), you can neatly unite a dark wall to a light ceiling.
Paint the dark-coloured wall as you normally would, except leave about 1 inch of blank space below the ceiling.
Cut a package of index cards in half lengthwise. Place the card halves in a shoebox.
Cut the top half off a paper lunch sack. Staple the lunch sack to the outside of the shoebox. The lunch sack will be a convenient trash container.
Fill a small disposable cup halfway with the dark paint. Place the cup and a flat artist's paintbrush in the shoebox. Set the shoebox on top of a fold-out ladder.
Mount the ladder comfortably. Hold one card half horizontally to the ceiling. Align the edge of the index card tightly against the wall.
Paint the blank inch of space with the dark paint and the flat artist's paintbrush. Along the card-protected ceiling, lightly drag the paintbrush across the wall, holding the brush perpendicular to the wall.
Toss the used card half into the lunch sack trash container. Do not reuse the index card or you might drag paint along the ceiling.
Continue painting the tops of the walls in this manner until the room is finished.
Prevent falling and tipping the ladder. Do not stand or rest on the top or first rang of the ladder.