misregistration

Misregistration is the failure of successive color separations to align correctly on the substrate during multi-color printing. When a press prints cyan, magenta, yellow, and black (CMYK) as separate passes or from separate units, each color must land in exact registration, typically within 0.002 to 0.005 inches of its intended position. When it does not, the printed image shifts, blurs, develops colored fringes, or shows overlapping halftone patterns that create moiré effects.

The symptom is visible immediately on the printed sheet. Text edges show color fringing, usually seen as thin lines of cyan or yellow separating from the black outline. Solid color areas may display gaps or overlaps. In fine halftone work, the dot pattern becomes visibly misaligned between colors, degrading image sharpness. The severity depends on the nature of the misalignment: horizontal shift, vertical shift, skew (angular rotation), or magnification (one color larger or smaller than others).

Sources of misregistration

Causes are mechanical and environmental. Worn gripper bars that do not grip the leading edge uniformly cause horizontal slip. Impression cylinder wear or incorrect packing height introduces vertical drift. Side guide wear allows lateral movement. Thermal expansion of the substrate as it moves through heated press units causes magnification misregistration, common in offset printing where the blanket cylinder is warmed. Humidity changes expand or shrink the substrate fiber itself. On flexographic presses, incorrect sleeve engagement or worn bushings create skew. Many presses include register sensors that detect position errors and trigger real-time correction via adjustable rollers or gripper position.

Prevention begins with preventive maintenance: inspecting and replacing gripper bars, measuring cylinder packing, and verifying side guide wear before each job. Temperature and humidity control in the pressroom reduces dimensional drift in the substrate. Color separation preparation matters too; separations should be trapped (small overlaps between adjacent colors) to hide minor misregistration. Starting with clean substrates and ensuring they feed straight into the press reduces slip and skew.

Misregistration is distinct from color matching problems. A press may be perfectly registered but print the wrong color shade due to ink formulation or lighting conditions. Conversely, a press may be out of register but reproduce the intended colors correctly. For applications like fine art reproduction, pharmaceutical packaging, or security printing, register tolerances are very tight and require frequent calibration. For general commercial work, tolerance is typically 0.010 inches or wider, allowing some misregistration to go unnoticed to the human eye.