CMYK or Pantone spot colours? What to confirm beyond a colour code

The artwork already names a Pantone colour. Why might the delivered carton still look different from what you expected?

A colour code identifies a reference, but it does not define the complete production and acceptance conditions. Also confirm the print route, the board, the finish and the sample and conditions used for comparison.^[1][2][3]

Clear conditions help distinguish an agreed acceptable variation from a result that fails the brief. They are not a reason to accept any colour difference.

CMYK and spot colours serve different needs

CMYK combines cyan, magenta, yellow and black process inks through halftone coverage and overprinting to reproduce images. Conventional spot-colour printing uses a separately prepared ink for a specified colour. In a conventional separated plate workflow, a spot colour requires its own plate.^[1][4]

Scroll horizontally to see the full table.

Avoid ranking the routes as simply “cheap” and “premium”. Ask the factory to explain feasible choices for the artwork and order.

A Pantone name in a file does not prove that production will use a separate spot ink. Prepress settings can convert spot colours to process colours. Confirm whether the factory will print a separate ink or simulate the target with the available ink set.^[5]

Either route may be considered. The quotation and the delivered job must use the same agreed understanding.

What C and U mean

In the Pantone Graphics System, C and U identify colour references on coated and uncoated paper. They do not describe whether the finished carton has a film laminate. The same colour can look different on these reference papers because of the interaction between ink and paper.^[2]

Supply the complete colour reference together with the actual board specification. Ask how the target will be achieved and approved on that material. A colour guide’s reference paper cannot stand in for every carton substrate.

This also makes a board change relevant to colour approval, even when the artwork, structure and order quantity stay the same.

Compare samples from the same production stage

An unlaminated print sample was approved, but the final carton needs a matt laminate. Should every later difference be attributed to a printing error?

ECI’s surface-finishing work documents changes after lamination and distinguishes matt and glossy laminated print conditions. Do not assume that the finished appearance will exactly match the unfinished print.^[3]

Keep separate references for the print process and the finished product. The process sample helps control printing. The final reference includes the agreed finish and establishes the overall appearance. Record each identifier and how the two references relate.

“Lamination changes colour” cannot excuse every mismatch. The final result still has to meet the approved target, with any change considered and checked beforehand.

Agree the viewing conditions

Pantone identifies D50 as an important viewing condition for print and packaging. Compare the sample and reference together under agreed conditions.^[6] A general lamp marked “5000 K” alone does not establish a complete standard viewing environment.^[3]

Two samples may match under one light and differ under another. This is illuminant metamerism: the match between the samples changes with illumination. It is more specific than the observation that any object’s appearance changes when the light changes.^[7]

Adobe also explains why a screen preview and the printed result are not equivalent. A screen view that has not been agreed for acceptance should not be the sole basis for approving colour-critical packaging.^[1]

A photograph is useful for identifying a location or describing an issue. Formal approval should return to the agreed physical reference, viewing conditions and any required measurement record.

Why “colour difference no greater than 2” can be ambiguous

ΔE describes colour difference, but different formulas can give different values. Datacolor’s technical guidance explains that there is no universal tolerance for every product. Material, application, measurement and visual requirements matter.^[8]

Do not write only “ΔE ≤ 2”. Agree the formula, such as ΔE00, the reference sample or target data, measurement conditions and locations, acceptance range and a review process when visual and measured judgements differ.^[8]

If those details are unfamiliar, ask the factory to propose an executable procedure and check it against the brand or customer requirement. Agree the procedure before production, rather than selecting a convenient threshold after a dispute.

A useful colour approval record

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Unknown entries are subjects for proofing and technical discussion. Filling them is more useful than an undefined promise to “match the colour exactly”.

Choosing CMYK or a spot colour determines a print route. Reliable approval also defines the target, material, finishing and judgement conditions.

Packaging colour approval checklist
Packaging Supply
https://globewhim.com/guides/cmyk-pantone-packaging-color-approval/

[ ] Artwork filename and revision:

[ ] Complete colour reference / approved physical sample ID:

[ ] CMYK / separate spot ink / agreed simulation, and areas using each:

[ ] Paperboard manufacturer and grade:

[ ] Lamination / varnish and final appearance:

[ ] Process sample and finished reference identifiers:

[ ] Agreed viewing conditions:

[ ] If required: ΔE formula / instrument conditions / locations / tolerance:

[ ] Review procedure when measured and visual results differ:

[ ] Change approval responsibility:

Mark unresolved items as “to confirm”. This checklist supports a supplier discussion and does not establish supply, engineering approval or a quotation.