When a density aim is still the right process control
When color already matches the signed proof and paper and ink have not changed, density is a fast way to hold ink film. Hue complaints, spot inks, or a new paper white need Delta E or SCTV. Stable density only means film thickness is stable.
Once color already matches the signed proof and paper and ink have not changed, density is a fast way to hold ink film. It is quicker than a full color-difference check every time. If the complaint is hue, the ink is a spot color, or the paper white has changed, a density aim is not enough: go back to Delta E or SCTV. Stable density only means the ink film is stable.
What it can hold
Same CMYK inks, same paper lot: a thicker film usually raises density. The press crew can watch a density window for drift on this run. That window is read at the moment color was approved, not copied from the last job ticket. Inside the window you do not need a full Delta E report every pull.
Outside the window, first ask whether it is ink film. If density did not move and the customer still sees a shift, it is a change density cannot hold: hue, paper white, or dry-back. Adding ink then only makes it worse.
Keep using it or stop
| Situation | Density aim | Look at instead |
|---|---|---|
| Process color, paper and ink unchanged, already matched | Can hold this run | Still spot-check Delta E once per shift |
| Spot-color fade or solid | Not enough | SCTV and Delta E |
| Paper or ink change | Stop the old window | Rematch color, then read a new density |
| Customer says hue is off, density still in window | Do not call it pass | Spectro |
Write this on the record
- Write which approved sheet this density came from.
- Note Status T or Status E.
- Strike the old window when paper or ink changes.
