MANUFACTURING / JAPAN SOURCING
Print colour approval: compare the proof and production conditions
For a colour-critical catalogue cover, an approved PDF and a production sheet may answer different questions. Identify the reference, paper, printing/finishing condition and viewing setup before deciding what changed.
Write down what the approval covered
Imagine a brand approving a catalogue cover on a laptop and later judging a coated production sheet under shop lighting. A visible difference is a reason to investigate, but these two observations alone do not identify a press error or an agreed colour target.
Sheridan’s printer guide distinguishes proofs used for content from proofs used for colour approval.[1] Ask what the offered proof is intended to establish in your workflow. A PDF is a file format; the agreed preparation and viewing process determine how it can be used.
- 1Released artwork: file revision and content/layout approval
- 2Colour reference: proof method, intended print condition and paper
- 3Production comparison: actual stock/finish under agreed observation
A comparison for a hypothetical catalogue cover, not a universal approval sequence or colour tolerance. The diagram does not reproduce printable reference colours.
Compare the intended print condition and substrate
Record the proofing method, simulated printing condition and profile where used, then the actual press process, ink/colour configuration, paper grade/colour and finish. Sheridan notes that a colour proof may use proofing paper rather than the final publication stock.[1] Find out what the proof represents and what it cannot reproduce for this job.
For the catalogue cover, make any coating, lamination or special-colour work visible in the specification. Agree whether the colour decision concerns the uncoated press sheet or the finished cover, and whether a physical trial is needed for an effect that the selected proof does not represent.
Make the viewing conditions comparable
EIZO explains why printed images can look different under different ambient light.[2] Before comparing samples from two locations, agree the observation conditions and record what was actually used. A phone photograph sent between those locations is useful for discussion, but does not transfer a controlled visual comparison by itself.
If the monitor is used for a colour decision, ask how that display workflow is controlled and what printing condition is being previewed. Do not treat an ordinary screen approval as equivalent to a separately agreed physical colour reference.
| Item | Keep with the approval | Ask when the result differs |
|---|---|---|
| Artwork | Keep with the approvalFile/revision, colour separations and what was approved | Ask when the result differsAre the proof and press sheet from the same released data? |
| Proof | Keep with the approvalMethod, intended condition/profile and reference ID | Ask when the result differsWas this proof approved for content, colour or both? |
| Paper and finish | Keep with the approvalProof stock versus production stock, coating/lamination | Ask when the result differsWhich substrate/finish differences were represented? |
| Observation | Keep with the approvalAgreed light/viewing setup and actual comparison conditions | Ask when the result differsAre the samples being judged under comparable conditions? |
| Decision | Keep with the approvalRetained reference, criteria, date and approval owner | Ask when the result differsWhat further evidence or corrected sample is needed? |
Investigate the mismatch without changing the reference silently
Return to the released artwork and the approved reference. Ask the printer to identify any changes in stock, ink/press setup, proof condition or finishing, and to provide the relevant production-control information. Bunseikaku describes controls for density, registration and paper type in its own factory workflow.[3] Those controls are not a substitute for the acceptance criteria agreed for your job.
Where measured colour differences form part of acceptance, agree the measurement method, conditions, locations and limits with the responsible technical team. Do not introduce a universal colour-difference number after the result arrives, or discard a material/finish difference because one measured patch is close.
Keep the accepted reference useful for a reprint
Identify and date the accepted proof or production reference, the artwork revision and the paper/finish specification. State which comments were resolved, what was accepted with an explicit exception and what remains outstanding. A generic “approved” email cannot answer all three.
For a reprint, confirm whether the same stock and process are available and which changes require renewed review. Share the reference and open questions with the supplier before comparing a revised price or promising a match.
Questions to send your supplier
Open supplier questions
Product: colour-critical catalogue cover Quantity, dimensions, destination and timing: Released artwork/revision and colour configuration: Proof method, intended print condition/profile and reference ID: Production paper, ink/process and coating/lamination: Please distinguish content approval, colour approval and final-finish approval. Propose viewing/measurement conditions, acceptance criteria and the approval owner. Identify what the proof does not represent and whether a physical trial is needed. Keep changes, exceptions and retained references visible for reprints:
Sources
- Sheridan — Press proofs: a primer
Printer article, 16 May 2017, distinguishes content and colour proofs and notes proofing-paper differences. Its costs, timing and soft-proof limits are not generalized to all workflows.
- EIZO — Environment preparation for colour matching
Manufacturer explanation of ambient light and reflected print appearance. Not a certification of a commercial print-viewing setup.
- Bunseikaku — Factory, printing and quality descriptions
Target sections describe paper/press/finishing scope and density/registration controls. No project-specific colour tolerance or process capability confirmed.