Rutherford Glossary
The vocabulary of color control on an offset press: makeready, DeltaE, ink keys, G7, closed loop. Clear definitions written from the pressroom floor.
34 terms
Calibration is the process of adjusting a press or device so it hits a defined target condition, typically through plate curves and density targets derived from a fingerprint run. A calibrated press is predictable; color control then keeps it that way in daily production.
CIELAB is the device-independent color space used in the graphic arts: L* describes lightness, a* the red-green axis and b* the yellow-blue axis. Because it models human vision rather than ink or light, it is the common language between proofs, presses and measurement devices, and the space where DeltaE is computed.
CIP3 and its successor CIP4 are industry standards that carry prepress data (mainly ink coverage per zone, as PPF or JDF files) to the press console for automatic ink presetting. Virtually every modern sheetfed and heatset press can consume CIP3 data.
Closed-loop color control is a cycle where a scanning device measures the printed sheet, software compares the measurements to the target values and the ink keys are corrected automatically, without manual input. Rutherford has deployed closed-loop systems such as ColorLoop on more than 1,000 presses in over 30 countries.
Learn more ›A color bar is the strip of measurement patches (solids, tints, overprints, gray balance) printed along the edge of the sheet, one patch per ink zone. It is what the scanning spectrophotometer reads to know the state of every zone; without a color bar there is no automated color control.
Color consistency is the ability to reproduce the same color run after run, shift after shift and site after site, within agreed tolerances. It is what brand owners actually buy from a printer, and the primary outcome closed-loop color control delivers.
Learn more ›Color drift is the slow wander of printed color during a run as temperature, ink-water balance and blanket condition evolve. Without in-run measurement it goes unnoticed until sheets are out of tolerance; a closed loop measures continuously and corrects the drift before it is visible.
Color management is the discipline of keeping color consistent from design file to proof to printed sheet, using profiles, standards, measurement and process control. On press, it materializes as measured targets and automated correction rather than visual judgment alone.
DeltaE is the standard measure of the difference between two colors in the CIELAB space: 0 means identical, and around 2 is the threshold most observers start to notice. Print contracts commonly require DeltaE 2000 below 3 against the reference; closed-loop control holds production inside that tolerance sheet after sheet.
Learn more ›Dot gain, or tone value increase (TVI), is the growth of halftone dots between the plate and the printed sheet, caused by ink spread and optical effects. Standards like ISO 12647-2 define target TVI curves; uncontrolled dot gain makes images darker and muddier than the proof.
Extended color gamut printing adds orange, green and violet to CMYK to reproduce most spot colors from a fixed ink set, eliminating ink changes between jobs. It demands very stable, measured color on press, which is why converters adopting ECG pair it with closed-loop control.
Fountain solution is the water-based mix that keeps the non-image areas of an offset plate ink-free, exploiting the repulsion between water and oily ink. Its dosage, pH and temperature directly affect ink transfer and color stability, making it a key variable the closed loop has to absorb.
G7 is the Idealliance calibration method, dominant in North America, that aligns presses on a shared neutral gray appearance and tonality rather than on fixed density values. Two G7-calibrated presses on different continents produce visually matching sheets, which is why global brands specify it.
Learn more ›Gray balance is the specific combination of cyan, magenta and yellow that produces a neutral gray on a given press and paper. It is the foundation of the G7 method: when grays are neutral, the whole reproduction tends to look right, and any color cast is immediately visible.
An ICC profile is a standardized file describing how a device (monitor, proofer, press) reproduces color, so color can be converted reliably between devices. In offset, output profiles like FOGRA51 or GRACoL define the target the press is expected to match on a given paper.
Ink density measures how much light a solid ink patch absorbs, which correlates with ink film thickness on the sheet. Density is what the press operator actually adjusts through the ink keys, while CIELAB and DeltaE describe the color the customer sees; modern color control connects the two.
Ink keys are the motorized screws along the ink fountain of an offset press: each one meters how much ink flows into its zone of the sheet. Setting dozens of keys per unit by hand is slow and subjective, which is why presetting and closed-loop correction automate them.
Ink presetting computes the starting position of every ink key from the ink coverage of the plates, before the press starts. Fed with CIP3 / CIP4 data from prepress, a good preset brings the first sheet close to color and leaves the closed loop only fine corrections to make.
An ink zone is the vertical strip of the sheet controlled by one ink key, typically 25 to 40 mm wide. A 40-inch press has around 32 zones per printing unit, and color control software calculates a correction for each zone independently.
ISO 12647-2 is the international standard for sheetfed and heatset offset: it fixes the CIELAB values of the primaries, tolerances, TVI curves and measurement conditions for standardized production. It is the reference in Europe and the basis of certifications such as PSO.
Learn more ›M0 to M3 are the ISO 13655 measurement conditions that define the light used by a spectrophotometer: M0 legacy tungsten, M1 with defined UV content (required by ISO 12647-2 for papers with optical brighteners), M2 UV-cut and M3 polarized. Comparing values measured under different M conditions is a classic source of color disputes.
Learn more ›Makeready is the setup phase between the end of one job and the first sellable sheet of the next: plates, paper, ink presetting and color adjustment. It is where offset printers lose the most time and paper; automated color control can cut makeready time by up to 45%.
Learn more ›Makeready waste is the paper printed and thrown away before color reaches the target at the start of a run. A conventional makeready can burn 200 to 500 sheets per job; closed-loop systems like ColorLoop reduce that waste by up to 65% by reaching target color in the first few sheets.
Learn more ›The OK sheet is the sheet approved at the end of makeready, by the customer or the shift leader, that becomes the color reference for the whole run. Closed-loop systems store its measured values and steer every following sheet back to that reference automatically.
PANTONE is the reference color language of the graphic arts: thousands of numbered colors with defined recipes and lab values, so a designer in Paris and a printer in Toronto talk about exactly the same color. Rutherford is a long-time X-Rite PANTONE partner, and ColorLoop Pack includes PANTONE fine-tuning for packaging work.
The press console is the control desk where the operator manages ink keys, dampening, register and speed. Closed-loop retrofits like those deployed by Rutherford connect to the console of virtually any sheetfed press, from 30-year-old machines to current models; a free console validation confirms compatibility in about two minutes.
Learn more ›Fingerprinting is the controlled test run that characterizes how a specific press prints: solid densities, TVI, gray balance and gamut on a given paper and ink set. The resulting data anchors calibration (ISO or G7) and gives closed-loop software an accurate model of the press to correct against.
Process control means continuously measuring production against defined tolerances and acting on deviations before they become waste or rejects. In the pressroom it covers density, DeltaE, TVI and registration, with reports that prove compliance to customers and auditors.
Registration is the precise alignment of the successive ink layers printed by each unit of the press. Misregister blurs images and text and shifts overprint colors; it is checked on register marks and corrected at the console alongside color.
A scanning spectrophotometer reads the whole color bar of a sheet automatically in seconds, instead of patch-by-patch hand measurement. Instruments like X-Rite IntelliTrax2 scan a 40-inch sheet in under 15 seconds and feed the measurements straight into closed-loop software such as ColorLoop.
Learn more ›A spectrophotometer measures the full reflectance spectrum of a printed patch, from which CIELAB values, density and DeltaE are derived. It is the reference instrument for color quality in print, far more complete than a densitometer that only reads ink density.
A spot color is an ink mixed to a specific recipe (often a PANTONE reference) and printed as its own ink, instead of being simulated with CMYK. Brand colors on packaging are usually spot colors, with tight DeltaE tolerances that make measurement and closed-loop control essential.
Standardization in print means producing to documented, measurable targets (ISO 12647-2, G7, house standards) instead of operator-dependent judgment. It makes quality repeatable across presses, shifts and plants, shortens makeready and is the prerequisite for multi-site color matching.
The substrate is the material being printed: coated or uncoated paper, board, label stock or film. Its whiteness, coating and optical brighteners change how the same ink looks and measures, which is why standards define different targets per substrate class.
The free Rutherford Check tells you in about two minutes if your press console is compatible with closed-loop color control.
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