A paint brush is required on trim molding and to paint the border or "cut–in", around trim and corners between walls and ceilings. Below are some techniques for handling a paint brush and applying paint with a minimum of mess. If you need to mask to paint a straight line between two paint colors, use the instructions for painting a straight line on trim molding and painting a white ceiling.
For improved control over a standard, straight cut paint brush, use a sash brush for brushing paint.
Hold the brush as you would a pencil or pen, grasping it around the ferrule—the metal band holding the bristles to the handle— with the angle of the bristles pointing up.
Fill a paint pail about half way and load the brush by dipping it into the paint pool. Lift the brush until the bristles clear the liquid and then tap them on the sides of the pail to work the paint in and blot any drips.
Apply the paint to the surface using back and forth strokes. Don't try to spread the paint too far, before the brush starts to drag, stop and reload it to continue painting. Start a little out from the end and paint back into the fresh paint then move forward with the next application.
Cut–in around walls and ceilings working from top to down. Brush around the ceiling first and then down the walls and along the baseboards. If you're painting a white ceiling first use these instruction and then paint walls using these instructions.
Paint trim molding starting at the top and working down, painting each section before moving to the next. For instance, paint the top of a window casing first, then paint down the two sides, before moving to the sill.