Color is achieved in stage lighting primarily through the use of colored squares of plastic called "gels." These small colored squares or sheets typically clip onto the front of the light, or are inserted in front of the bulb, to color the light in any one of hundreds of available hues.
Lighting designers plan out their lighting themes for their productions by carefully going through each play or set list to get a feel for the overall theme, atmosphere, and approach to be illuminated, and jotting down the most important lighting elements from scene to scene from a technical standpoint, as well as notating the appropriate emotions, colors and combinations to emphasize.
The designer will then choose an assortment of colored gels to use in specific arrangements for the production, notating locations, colors and directions in a detailed drawing or blueprint called a "light plot." The light plot not only makes note of each stage light's location, but also makes note of the precise gel color and number to be used with that light, as well.
The use of color in stage lighting is an especially vital aspect of any theatrical production or concert because it provides the visual look and feel of the entire production, and the audience senses this atmosphere even as the curtain rises. As the lights come up on a ghost story or tragedy, for instance, the audience will be able to sense this almost immediately simply through deep contrasts of light and shadow, and the use of darker, somber hues in the lighting color palette. A cheerful drawing room comedy or musical, on the other hand, will typically utilize brighter, flatter lighting, with fewer shadows, lighter, softer colors and less contrast. Each production offers the opportunity for a thousand different color combinations and approaches.
Colored stage lighting is also an important way to depict the production's setting, time, or season. For instance, the use of soft, streaming yellows helps the audience believe that the play is taking place on a midsummer's morning. Deep, dark blues and silvers, however, might indicate that the action was taking place on a midsummer night, instead. Dapples of red, orange, yellow and brown, meanwhile, might alert the audience that the action is taking place on a lovely autumn day.
Stage lighting also utilizes color to mimic important onstage lighting elements, with rich reds and oranges used in a directional manner, for instance, to mimic the warm glow of a fire. Softer key lights can also seamlessly echo small onstage lighting elements such as lamps or even candles.
Colored lights, when used creatively, can also be used for visual effects within a stage production, and can do so with surprising effectiveness. A sudden, brutal wash of deep red lights upon white or pale surroundings might instantly call to mind a bloody murder, while on the gentler side, a bunch of small flickering colored lights might be used to simulate a computer screen or science fiction element.
Colored stage lights don't just illuminate characters onstage in a literal sense, but do so metaphorically, as well. They can give the audience a sudden visual insight into the mind or mood of a character, with a wash of pink to show a character suddenly in love, or a pale green to imply sickness or weakness, or a pale blue to denote depression or sadness.
Colored spots not only visually isolate a character, for example, but also create a powerful visual impression of everything from strength to yearning to illumination to loneliness or disconnection depending on the colors chosen.