Start With Good Equipment

Before you start painting walls, you need to cut in the edges with a paintbrush. Cutting in happens when areas are too tight for a roller, such as in corners, along baseboard and trim, and where the wall meets the ceiling.

It is a craft that requires a steady hand. According to this site:Angled Sash Paint Brush

“Cutting in” is the art of drawing a straight line, separating two colors using only the paint brush – no masking tape or other aid. You often see it at the edge where a wall color is cut into a different ceiling color. When cutting in, follow these simple rules:

Use a fully loaded brush.

Using the brush parallel to the area to be cut, let the paint brush open up into a semi-oval and bring it into the line you are cutting. Follow the line until the line of paint begins to break up. Repeat. It is best to cut in while breathing out or holding your breath.
Work into the previous area.

See more here:  Painting Tips | Professional Painting Tips & Techniques from Purdy

If you don’t have much practice with cutting in, there are some tools that will make it easier. Purdy and Wooster make some of the best paint brushes and rollers in the industry, so using a high-quality 2.5-inch angled brush will help you make a nice straight line of paint.

You want to load a decent amount of paint on the tip of the brush (about one inch) and then pat it off on the inside of the can. Using the longest bristles of the angle, pull the paint both directions along the line between the wall and the ceiling, following by back rolling it to smooth it out.

This video provides excellent tips for cutting in when painting along the ceiling:

As mentioned in the video, you always want to cut in before rolling the walls so you don’t see what he refers to as “haloing”. If you’re a lone painter, this also requires painting in sections, so after you cut in an area along the ceiling and/or corners, paint the walls too so the color stays smooth and blends.

Using Painter’s Tape To Cut In

Many people use painter’s tape to cut in, as it offers more work up front but less aggravation with trying to hold your hand steady and draw that perfect line. Painter’s tape is less sticky, so it leaves no residue, and you can buy it in two-inch wide rolls to provide a wide area of coverage.

If you are going to use a brush to cut in, you would still want to use painter’s tape in certain areas:One Inch Painters Tape

When you master cutting in, you need to apply masking tape to only the tops of windows, doors and the baseboard. And the only reason you do this is to avoid spattering the woodwork when you roll paint onto the walls. Masking less saves you time and money, and you don’t have to worry about paint creeping under the tape or the paint job getting messed up when you pull off the tape.

The Best Tips for Cutting in Paint | Family Handyman

Being able to see the area you are cutting in is critical, and sometimes this is difficult because your body blocks the light in the room. You might want to consider wearing a headlamp so the area is well lit, especially if you are painting alone.

Cutting in takes time, so if you are limited in that arena, talk to your favorite local Denver painter to get a free estimate on doing the job for you.