Halo / Edge Feathering
Appearance: Thin ink band extending beyond the intended print boundary around solid elements.
Root causes: Excessive impression pressure squeezing plate beyond the designed contact zone; over-soft mounting tape; ink viscosity too low. Fix: Reduce impression in 0.02–0.05 mm increments; verify tape durometer; raise viscosity to upper target range.
Bridging (Filled Highlights)
Appearance: Fine highlight dots fill in and merge, losing detail in light tonal areas.
Root causes: Excessive impression; low viscosity; anilox BCM too high for the application; shallow plate relief. Fix: Reduce impression pressure; increase ink viscosity; specify lower BCM anilox; verify plate relief depth specification.
Pinholing (Voids in Solid Areas)
Appearance: Small unprinted voids in solid ink areas — white specks or pinholes.
Root causes: Viscosity too high (insufficient transfer); insufficient corona treatment (minimum 38 dynes/cm for water-based on film); anilox cell volume too low; substrate contamination. Fix: Reduce viscosity; verify corona level; use higher BCM anilox; clean substrate path.
Banding (Periodic Density Stripes)
Appearance: Repeating stripes of higher or lower density running parallel to print direction at regular intervals.
Root causes: Anilox roller runout; doctor blade chatter at specific speeds; gear pitch error (gear-driven presses); ink pump pulsation. Fix: Measure anilox runout and replace if out of tolerance; check blade pressure; inspect gear condition; add pump dampener.
Mechanical Ghosting
Appearance: Faint repeat image offset exactly one anilox circumference from the intended printed element.
Root cause: Ink starvation — anilox cells depleted by a high-coverage element cannot fully refill before the next repeat. Fix: Specify higher BCM anilox; increase ink supply flow rate; rearrange element layout where possible.
Ink Misting / Spray
Appearance: Fine ink droplets scattered around print elements.
Root causes: Press speed too high for ink viscosity; ink filaments snap on separation, creating droplets. Fix: Increase viscosity; consult ink supplier for high-speed-optimized formulation; reduce speed to confirm diagnosis.
Color Density Drift During Run
Root causes: Viscosity change from evaporation or temperature rise; progressive anilox cell clogging; impression thermal drift on long runs. Fix: Install automatic viscosity control; deep-clean anilox between jobs; monitor impression control for thermal expansion compensation on runs over 2 hours.
