spot color
In offset printing, any color generated by an ink, pure or mixed, that is printed using a single run.
spot color: one ink, one pass, one color
A spot color is a premixed ink applied in a single press run to print a specific area of a design. Unlike process color (cyan, magenta, yellow, black), which builds colors through overlapping halftone dots, spot color lays down a uniform hue in one pass. The printer mixes the ink to a precise formulation before the run begins, then loads it into a dedicated ink station on the press.
Spot colors are identified by standardized matching systems, most commonly Pantone Matching System (PMS) numbers. A designer specifies PMS 185 (a bright red), PMS 287 (a corporate blue), or PMS 871 (a metallic gold), and the press operator mixes ink or opens a prepared can to that exact specification. This removes the guesswork of color reproduction and guarantees consistency across print runs, which is critical for brand identity and packaging.
The practical advantage is cost and color fidelity on short runs. A two-color poster printed with two spot colors requires only two ink stations and two passes through the press, whereas the same design in process color demands four stations and much tighter registration. For runs under 5,000 sheets, spot color printing is often cheaper than process. Metallic, fluorescent, and opaque white inks are only available as spot colors; they cannot be mixed from process primaries.
Limitations and trade-offs
Spot color becomes expensive for full-color photographic work or gradients. Reproducing a photograph requires either four process separations or 10 to 15 spot colors, each requiring a separate press pass and film. The name "spot" reflects the original use: printing small, defined areas of solid color, not continuous tone. Modern offset presses can run six, eight, or more color stations, but each additional color adds time and cost.
Registration accuracy determines success. If cyan and yellow spot colors misalign by 0.1 millimeter on a two-color job, the overlap creates a visible gap or a muddy edge. Gravure and flexography handle spot color differently, relying on chemically etched or relief surfaces rather than film separations, but the principle remains: one ink station per color.