# Print colour consistency: why run two never matches run one

> What causes colour variation between label runs, how much is normal, and when to specify a spot colour, a proof or a retained reference sample.

Pillar: printing · Updated: 2026-11

**Our view.** Buyers expect run two to match run one exactly, and print does not work that way. Our position: approve a physical sample, keep it, and compare future runs against it rather than against memory. If the colour is a brand asset, pay for a spot colour instead of hoping the CMYK conversion lands in the same place twice.

Buyers often expect the second print run to match the first exactly. It rarely does, and understanding why separates a normal variation from a supplier problem.

## What varies

| Factor | Effect |
|---|---|
| Ink batch | Small hue shifts between ink lots |
| Substrate | Same ink on coated vs uncoated reads differently |
| Press conditions | Temperature, speed, anilox volume |
| Digital vs flexo | Different colour engines entirely |
| Laminate | Gloss vs matte changes perceived colour |
| Light | The same label looks different under shop lighting |

A visible-but-small variation between runs is normal in print. A large shift usually means the substrate or the print method changed — not that the printer was careless.

## How much is normal

In flexo and digital, a Delta E of around 2–3 is generally imperceptible to most viewers; above 4–5 it becomes noticeable side by side. Without a measured reference, "match the previous run" is an opinion rather than a specification.

The practical approach: approve a physical reference sample, keep it, and compare future runs against it rather than against memory.

## When to specify a spot colour

A spot colour is a pre-mixed ink matched to a reference (Pantone or a physical swatch). It is the only way to get an exact, repeatable brand colour across runs and substrates.

Cost: an extra plate in flexo, or a dedicated ink in digital — and a setup charge. Worth it for a brand colour on packaging; rarely worth it for a one-off sticker run.

## Proofs

- **Digital proof** — a PDF or screen preview; good for layout, useless for colour.
- **Contract proof** — a calibrated inkjet proof on the actual stock; a reasonable colour reference.
- **Press proof** — a short run on the production press; the most accurate, and the most expensive.

For brand colours, a contract proof or a physical sample is the minimum. For everything else, approving on screen is acceptable if the design is not colour-critical.

## What this means for buyers

**Keep the approved sample.** It is the only objective reference for the next run.

**Do not expect exact matches across substrates.** The same ink on paper and film looks different; that is physics, not error.

**Spot colour is a budget decision.** Exact brand matching costs a plate; decide whether the match matters enough.

**Ask what proof you are approving.** "Proof" covers three very different things.

## Quick answers

**How much colour variation between print runs is normal?**

A small shift is normal. A colour difference (Delta E) of about 2 to 3 is imperceptible to most viewers, 4 to 5 becomes visible side by side. Larger shifts usually mean the stock, the print method or the ink batch changed rather than the printer being careless.

**How do I keep a brand colour consistent across runs?**

Specify a spot colour mixed to a reference and keep an approved physical sample as the contract. Spot colour costs an extra plate or a dedicated ink, but it is the only approach that reproduces the same colour across substrates and runs.

## Sources

- ISO 12647-6:2020 — Process control for flexographic printing — https://www.iso.org/standard/75219.html
- ISO 12647-7:2016 — Proofing processes working from digital data — https://www.iso.org/standard/66426.html