A useful supplier color specification makes the acceptance decision reproducible. It identifies the approved standard, the exact measurement method, the tolerance and component limits, the sampling plan and what happens when results are borderline. A target color plus “ΔE ≤ 1” is rarely enough.
What the specification must answer
What is the target?
Name the physical master, spectral target, revision and authorised owner.
How is it measured?
Define instrument geometry, settings, sample presentation, conditioning and calculation.
How is it accepted?
State tolerance, sampling, rounding, retest, visual review and escalation rules.
Technical fields to include
| Specification field | Example of the required precision |
|---|---|
| Instrument condition | Geometry, SCI/SCE, aperture, UV condition and transmission or reflectance mode. |
| Calculation | Illuminant, observer, color space, ΔE formula and any parametric factors. |
| Sample method | Backing, thickness, layers, orientation, location, temperature, cure and conditioning. |
| Acceptance limits | Total color difference plus any ΔL*, Δa*, Δb*, hue, chroma, gloss, opacity or index limits. |
| Sampling and records | Units per lot, readings per unit, averaging rule, retained sample and report fields. |
Use normative language where it matters: “shall” for requirements and “should” for recommendations. Add the applicable product or test standards by exact designation and revision rather than relying on informal shorthand.
Define the acceptance workflow
01
Measure the agreed sample
Verify the instrument and follow the documented presentation and sampling plan.
02
Apply the complete rule
Check total difference, component limits and any separate appearance requirements.
03
Handle borderline results
Use the stated retest, visual review and authorised disposition process.
Align instruments before the first shipment
Exchange physical correlation specimens that span the acceptable color region. Measure them at both sites, compare spectra and color values, and agree how systematic bias will be handled. Repeat the exercise after material instrument service, replacement or method change.
Keep color and appearance separate where necessary
A spectrophotometer result may not control gloss, texture, sparkle, grain or visual defects. Add separate appearance requirements and controlled visual assessment when the product needs them.
Link the document to tolerance setting, master and working standards, instrument agreement and sampling.
Last reviewed 21/09/2026 · Level: Intermediate
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