Colour stays consistent when it is specified by numbers, not by eye: a colour target for each critical colour (measured values, not only a swatch name), a tolerance in ΔE (usually CIEDE2000) agreed per colour, the measurement conditions (instrument settings, substrate), a signed master sample, and an agreed lighting for visual checks. Without these, two good printers can deliver two different 'right' colours.
- Name the critical colours: usually the logo and brand colour, not every tint.
- Give measured targets and agree a ΔE tolerance per colour.
- Specify measurement conditions so both sides measure the same way.
- The substrate changes the colour: the target must refer to the real material.
- Check visually under a defined light source, next to the master sample.
Why colours drift
- Different substrates: the same ink looks different on white paper, textured paper, film or metallised material.
- Different processes: a spot ink in one process and a colour built from process inks in another.
- Different suppliers or sites: each with its own calibration and habits.
- No numeric target: the reference is a previous print, which may already be off.
- Different light: approval under office light, complaints under shop light.
What a colour specification should contain
| Element | What it is | Why it matters |
|---|---|---|
| Critical colours | List of colours that must match (logo, brand colour) | Focuses control where the brand is recognised |
| Colour target | Measured values (e.g. CIELAB) on the real substrate | Gives an objective reference, not a memory |
| Tolerance | Maximum ΔE allowed per colour, usually CIEDE2000 | Defines what is acceptable before printing starts |
| Measurement conditions | Instrument settings and measurement mode (ISO 13655) | Two instruments set differently give different numbers |
| Master sample | Signed approved print | Visual reference for colour and finish |
| Viewing conditions | Standard light booth or agreed light source | Avoids disagreements caused by lighting |
Ranges and multi-supplier sourcing
When a range is printed by several suppliers or in several plants, give all of them the same targets, tolerances and measurement conditions, and ask for measurement reports with deliveries. Products that sit next to each other on the shelf are compared by the consumer even if they come from different factories.
Spot colours and process colours
Brand colours are often defined as a spot colour reference. Some printing processes reproduce them with a dedicated ink, others by combining process inks. Both can work, but not every spot colour is reachable in every process and on every material. Ask the supplier early which brand colours are inside their gamut on the chosen material and agree the target on a printed sample.
Measured, not guessed
UltraPixel measures colour spectrally against agreed targets. To compare suppliers on the same basis, send them the same colour specification, or ask for samples printed on your material.
Frequently asked questions
What is ΔE in label printing?
ΔE is a number that expresses the difference between two colours. The CIEDE2000 formula is commonly used; the acceptable value is agreed per colour between buyer and printer.
Why does the same colour look different on two labels?
Because of different substrates, printing processes, calibration or lighting. A measured target on the real material and agreed tolerances reduce the difference.
Is a Pantone number enough to specify a label colour?
It is a starting point, but the colour also depends on material and process. Add a measured target on the real substrate and a tolerance.
Under which light should labels be approved?
Under an agreed standard light source, ideally in a light booth, next to the signed master sample.