One fixed ink set can serve many colours across a product family
Conventional packaging often combines CMYK imagery with individually mixed spot inks for brand panels, range colours or functional marks. Every dedicated ink may bring a plate or unit, an ink change, a wash-up and another production variable. Expanded colour gamut, usually shortened to ECG, keeps a standard set of process inks on press and builds many of those colours from screened combinations. CMYKOGV is the familiar seven-colour arrangement: cyan, magenta, yellow, black, orange, green and violet.
That fixed palette can be attractive for a range containing many SKUs. Jobs may be grouped more efficiently when their artwork separates into the same ink set, and a colour used on one pack can be described by a repeatable process build instead of a newly mixed ink. The commercial gain varies with run length, design, press layout, changeover practice and the percentage of colours that the characterised system can reproduce.
A single carton carrying one critical corporate colour presents a different case from forty related packs that use dozens of secondary colours. ECG earns consideration when the complete range can benefit from the same fixed ink set.
A measured press characterisation guides seven-colour separation
In a controlled ECG workflow, the designer does not invent orange, green and violet builds independently. The workflow prints and measures colour targets using the intended inks, screening, sequence and substrate. The resulting characterisation describes how primary inks and overprints behave together. Production separation software then creates the process channels from the applicable characterisation and separation settings while managing black generation and transitions.
ISO/TS 21328 describes procedures for creating multicolour CMYKOGV characterisation data. FOGRA55 provides a seven-colour exchange space used for communication and testing. Neither is a promise that a particular press, ink set or board naturally reaches every coordinate in the exchange space. Production still needs its own applicable profile or characterisation and stable process control.
The extra inks widen selected parts of the gamut
Orange can extend reproduction between magenta and yellow, green between cyan and yellow, and violet between cyan and magenta. This can improve some saturated brand and packaging colours that CMYK pulls inward. The gain is uneven: paper colour, ink pigments, ink-film thickness, solid-ink condition and overprint behaviour shape the boundary in every direction. ECG will not make every RGB photograph brighter, and an image already sitting comfortably inside CMYK may change very little.
Where a dedicated spot ink remains necessary
A specially mixed spot ink may reproduce an out-of-gamut brand colour more closely. Metallic, fluorescent, opaque white and other functional inks have physical properties that process mixtures do not imitate. Large flat panels can also expose screening texture or small process variation that is less visible in pictorial artwork. Compare both options on the selected material at the viewing distance of the pack.
Measurement helps settle colours near the boundary, but numbers need a defined reference and tolerance. A spectral value from a brand standard, approved ink drawdown or retained printed sample provides a firmer target than a colour picked from an uncalibrated display. The brand and spot colour article shows how to identify that reference and the person authorised to approve it.
Hybrid specifications are possible: CMYKOGV for the wider range plus a dedicated ink for one protected colour or special effect. Whether that is sensible depends on the number of units, artwork, cost and production plan. Seven process colours are a method, not an obligation to remove every spot separation.
Proof the series as a family, then preserve the separation recipe
A proof for ECG has to simulate the intended multicolour condition or make its limits explicit. Ordinary CMYK office output cannot approve the extra gamut. Include the brightest range colours, neutral greys, small reversed type, photographic transitions and difficult overprints in the test. Where decoration or varnish changes the surface, assess that effect separately on a physical sample.
Retain approved colour targets, profiles, separation settings, artwork versions and measurement reports with the range. A later pack can use the same documented target and separation workflow. If the board, ink set or printing condition changes, compare a new characterisation instead of assuming that the old seven-channel values will travel unchanged. The print colour standards article explains how a named condition supports that record.