Every show is designed in a different style. A set painter needs to be able to adapt to the style dictated by the set designer, whatever it may be. One day, a painter might need to paint in an abstract style, the next he might be called upon to paint a series of flats to look exactly like the interior of a real house. Familiarity with a variety of styles is an important skill for a set painter.
A set painter needs to master the art of creating perspective in his work. Sometimes, flat set pieces need to represent a three-dimensional scene. The painter needs to know how to create perspective in art in order to create the illusion of depth. The theory behind perspective is that there needs to be a vanishing point on the horizon that lines are moving towards. By following the lines that move toward the vanishing point, the artist sees how objects need to be made smaller as they move toward the imaginary distant point.
Theatre sets often comprise more than just plain, painted flats. Interiors, exteriors, nature scenes and abstract designs all need to be created using a number of different materials. Set painters need to texturize many surfaces by applying layers of paint, working with sponges and special tools such as a wood-graining paint applicator to create the appearance of various textures that aren't really there.
Another common problem is that sets that are newly painted look too new or artificial. When you work on a period piece designed in a realistic fashion, often fresh coats of paint stand out like sore thumbs as being inappropriate to the era. As a result, you need to age the paint jobs somehow. One way this is done is by "washing" the floor, wall or object you paint. This means adding another coat of a similar color that has been mixed with water. Uneven application of the wash helps create the impression of typical, uneven fading that happens over time.