In 60 seconds
- "The colour is wrong" is three different problems. (1) Vivid on screen, dull in print — gamut: a backlit RGB display against reflected CMYK ink, and saturated blues, greens and oranges often sit outside CMYK. (2) The first run was fine, the second drifted — batch variation: ink batch, worn anilox, pressure and speed, a new substrate lot, drying. (3) It matches under the light booth but not in the store — metamerism. Each has a different fix, and treating one as another wastes a reprint.
- Write the tolerance as a sentence you can inspect against. For example: brand colour Delta E00 2.0 or below, formula CIEDE2000, illuminant D50, measurement condition ISO 13655 M1, 4 mm aperture, measured over black. "Delta E under 2" without the formula is not a specification: dE76 and dE00 do not mean the same thing at the same number.
- The eye's line is at 3.5. 0–1 is imperceptible, 1–2 is visible only to a trained observer under controlled light, 2–3.5 is noticeable on close inspection, above 3.5 an ordinary shopper sees it on shelf, above 5 it reads as a different colour. Hold brand colours at 2.0 or below; secondary elements can be looser.
- Spot colour for the brand, CMYK for the image. A spot is one plate, one ink, one solid: the most stable way to hold Delta E. A CMYK-built solid moves with ink film and registration, and deep blues and bright oranges often cannot be built at all.
- Approve under D50, not under office fluorescents or warm light. ISO 3664:2025 names D50 (5,000 K) as the reference illuminant, 2,000 lx +/-500 for critical comparison (P1) and 500 lx for routine appraisal (P2). European buyers often check under D65 and stores under LED, so look at the same sample under at least two sources.
- Clear and silver stock needs a white backing. Without it the colour you see is ink plus contents: a clear label turns greenish on a dark bottle and muddy on an amber one. That is not a printing fault.
1. Diagnose first: three mismatches, three owners
After a complaint, the fastest question is not "what colour is it" but "compared with what, and under which light".
| What you see | Usually found | Real cause | What to do |
|---|---|---|---|
| Vivid on screen, dull or grey in print | First proof or first run | Gamut: saturated blues, fluorescent greens and bright oranges are outside CMYK | Supply the brand colour or Lab value; print as a spot or the nearest build and report the measured Delta E. A screenshot is not a standard. |
| First run fine, second run off | Repeat order, new supplier | Batch variation: different ink lot, worn anilox, pressure and speed changes, new substrate lot, under-drying | Keep a signed reference sample; measure the first-off of every run against it and stop the press when it exceeds tolerance |
| Two samples match side by side, then differ elsewhere | Customer in-store or in the warehouse | Metamerism: different ink formulations that match under D50 and separate under LED or fluorescent | Ask the printer to check under the light in your own store; move to a spectrally matched formulation if it persists |
| Colour varies across one roll | On the labelling line | Uneven ink film across the web, uneven impression, varnish thickness, wind tension | Define where to measure (clear of the die line and creases) and take three points per roll, report the median |
2. How to put Delta E into a purchase order
Delta E is a number for "how far apart two colours are", but the same number is not the same thing under different formulas. CIE76 (dE76) is a straight-line distance in Lab; CIEDE2000 (dE00) is weighted for human sensitivity, is more accurate for blues and neutrals, and is therefore stricter at the same value. Packaging specifications today normally call for dE00.
| Delta E00 | What the eye sees | Production meaning |
|---|---|---|
| 0 – 1.0 | Imperceptible, even to a trained eye | Laboratory precision; achievable on coated stock with tight control |
| 1.0 – 2.0 | Visible only to a trained colourist under controlled light | The target band for brand colours; the usual "commercial match" |
| 2.0 – 3.5 | Noticeable on close inspection | Acceptable for secondary elements and backgrounds; borderline for a hero colour |
| 3.5 – 5.0 | Obvious to a shopper on shelf | Not acceptable for brand colour; reprint |
| 5.0 + | Reads as a different colour | Reject |
A number alone is not a specification. Six items make it complete: formula (CIEDE2000), illuminant (D50 or D65), measurement condition (ISO 13655 M1 with UV, M2 without), aperture (large aperture is steadier on textured stock), backing (clear film must be read over black and over white), and measurement position (solid area, clear of die lines, creases and uneven varnish). Miss one and you buy a dispute.
3. Set the tolerance by substrate, not one number for everything
Delta E 2.0 is achievable on bright coated board and physically impossible on natural kraft, whose gamut is simply narrower. Quoting tolerance by substrate prevents most arguments later.
| Substrate | Suggested tolerance (Delta E00) | Commonly achievable | Main variable |
|---|---|---|---|
| Coated board / art paper | 1.5 – 2.0 | 1.0 – 2.5 | Gloss level affects the visual read; metamerism |
| Uncoated paper | 2.0 – 3.0 | 1.5 – 3.5 | Surface scatter; ink absorption varies by lot |
| Natural kraft | 3.0 – 4.5 | 2.5 – 5.0 | Brown base pulls every colour down, warm tones most |
| Recycled fibre | 3.0 – 4.5 | 2.5 – 5.5 | Grey base; whiteness varies between lots |
| Flexible film (PE / PP / PET) | 2.0 – 3.0 | 1.5 – 3.5 | Surface treatment, stretch, and reading the formed label rather than flat film |
| Corrugated, direct print | 3.5 – 5.0 | 3.0 – 6.0 | Flute shadow; uneven liner absorption |
Two practical reference points: contract proofing commonly allows 2.5 Delta E00 on a spot solid, and a plant with a measured production standard can hold a spot to 1.5 Delta E00 at 5,000 K. The traditional visual wording is "half a Pantone shade", which is looser than the numbers and suits secondary colours.
4. Spot or CMYK: a question of stability
| Spot colour | CMYK build | |
|---|---|---|
| Run-to-run consistency | Good: one ink, one solid, small ink-film changes matter little | Weaker: built from dots, so ink film, registration and anilox all show up in the colour |
| Gamut | Reaches colours outside CMYK (metallic, fluorescent, specific brand shades) | Limited: bright blues, fluorescent greens and vivid oranges usually cannot be built |
| Cost structure | Extra plate and wash-up: heavy on short runs, economical at volume | No extra plate; suits images, gradients and small multi-colour artwork |
| Change flexibility | Changing ink means wash-up and re-matching mid-run | Curves can be trimmed, but a solid's headroom is small |
| Best used for | Logo background, brand red or blue, colours fixed by regulation | Photographs, illustration, gradients, secondary backgrounds |
The common mistake is building the whole label in CMYK, including the one brand colour that must not drift. The opposite mistake is all-spot artwork with photographs, which then print as coarse dots. The workable split is spot for the brand colour, CMYK for the image, with total ink and drying controlled where the two meet so no gloss step appears at the boundary.
5. Viewing light: approve the sample under the right lamp
ISO 3664:2025 (fourth edition, published July 2025) defines the viewing conditions: reference illuminant CIE D50 (5,000 K), colour rendering index 90 or above, neutral grey surround, no stray ambient light. Illuminance is specified in two bands: P1 at 2,000 lx +/-500 for critical comparison between artwork and proof or between proof and press sheet, and P2 at 500 lx for routine appraisal. The 2025 edition adds P3/P4 (D50 with UV excluded), corresponding to M2 measurement in ISO 13655, for print that will mainly be seen indoors; P1/P2 correspond to M1.
Three rules in practice: don't sign off under office fluorescents, warm light or a window; keep measurement and viewing in the same condition (M1 with P1/P2, M2 with P3/P4), or the numbers and your eyes will contradict each other; and check once under the light where your customer actually looks at the label — supermarket LED, pharmacy halogen, daylight. Metamerism only appears when the light changes.
6. Clear, silver and dark stock: white first, then colour
Unprinted clear BOPP or PET shows the contents through the ink: an amber liquid turns blue towards green, coffee brown muddies red, opaque white lifts everything. To control colour you need a white backing, sometimes two hits, so the final colour is white opacity plus ink rather than ink alone. Silver PET and foil are harder still: metallic reflection makes translucent inks change with viewing angle, so either print white underneath or use a genuinely opaque ink.
On dark and kraft stock, build the standard on that stock. Holding kraft to a Lab value measured on white paper cannot work; print a reference on the actual substrate, measure and store its Lab, then compare each run against that. Shrink film adds one more step: after shrinking, dots deform and colour deepens, so approve the shrunk finished label, not the flat sheet.
7. Signing and acceptance in six steps
| Step | What happens | What is kept |
|---|---|---|
| 1 Colour data | Brand reference (Pantone or spot number) plus Lab; if there is no Lab, send a physical sample | Reference and Lab written into the order |
| 2 Proof type | State whether it is a digital proof (content only), a press proof, or an on-press approval | Proof type and charge noted in the quotation |
| 3 First-off signing | Compare the first-off in a D50 booth and both sides sign | Three signed reference cards (customer, plant, file) with date, light source and Delta E |
| 4 Every run | Measure the first-off of each run against the card; stop the press if out of tolerance | One measurement record per run |
| 5 Sampling rule | Three points per roll, report the median, avoid die lines and creases | Positions and aperture written into the acceptance spec |
| 6 Disputes | The signed card and the measurements are the reference, not an opinion | Investigate at step 4 rather than reprinting blindly |
This applies to small orders too — small orders are exactly where the signed sample gets skipped, and where the next repeat discovers nobody remembers the previous colour. A reference card costs far less than a reprint.
8. Six items to include in an enquiry
- Colour reference or Lab value (a physical sample if there is no Lab — not a screenshot).
- Target Delta E, formula and illuminant (e.g. Delta E00 2.0 or below, D50, M1).
- Substrate and finish (art paper, synthetic, clear PP, silver PET; varnish, matte lamination, foil).
- Whether the stock is clear or metallic, and how many white hits are needed.
- Proof type (digital, press proof, on-press approval).
- Acceptance sampling rule (points, positions, aperture, backing).
With those six in the enquiry, the price and the tolerance you get back are executable rather than "as close as possible".
Related reading: Specifying a roll of labels, Label applicator compatibility, Custom shapes and dies, Barcodes that will not scan, Ink and adhesive safety, Five ways to verify a label supplier.
- Artwork: AI, PDF, EPS or PSD with fonts outlined or embedded; include the die line if you have one; 20MB per file. A photo or screenshot is fine if the design is not final.
- Finished size and shape (round, square, custom; a die-line file is ideal).
- Quantity: how many versions, how many per version, and whether it ships in rolls or cartons.
- Material and where the label sits: paper, synthetic paper, PE or PET; outside the pack or inside.
- Destination market and the standard to meet (Hong Kong, Southeast Asia, EU food-contact rules).
- Required delivery date: samples and digital work about 24 hours, small runs about one week, bulk about 15 days — confirmed against the actual schedule.
Your contacts: quotations Ms Zeng +86 180 1199 6161 | sales Mr Hong +86 189 2511 1128. We reply within the working day (Monday to Saturday); for urgent work please call.
Send the enquiry in one click (subject and six-point list already filled in)