What a color-difference deviation report cannot omit
The report must state ΔEab, which signed sample it is against, the M condition, the geometry, and the backing. If any one is missing, do not call it a pass.
The report must state ΔEab, which signed sample it is against, the M condition, the geometry, and the backing. If any one is missing, do not call it a pass.
If the report lacks this, do not conclude
Color-difference deviation compares the printed sheet with the signed sample. In ISO 12647-2 the common upper limit for the four process colors is ΔEab 5. Use the version the contract adopts. It is not the variation between one sheet and the next. If the conditions or the object are missing, nobody else can check this conclusion.
Report check
| Item | Do this | Do not |
|---|---|---|
| Color-difference deviation | The report must state ΔEab, which signed sample it is against, the M condition, the geometry, and the backing. If any one is missing, do not call it a pass. | Only write a feeling |
| The common mistake | Do not treat ΔEab 5 as the variation allowed from sheet to sheet. Variation uses another set of numbers, not this rule. | Leave the mistake in place |
| What to keep | The report must state ΔEab, which signed sample it is against, the M condition, the geometry, and the backing. If any one is missing, do not call it a pass. | Only leave the word passed |
Check before you file it
- First see whether the contract says deviation or variation.
- Note the geometry, the M condition, and the backing.
- Compare only two readings taken under the same conditions.
