Category Archives: Paper Packaging

Weak Print Color

Too much water in the ink due to water in the press station or operator error

Replace ink or add fresh ink. Repair station to drain wash up water. Measure amount of water added to ink

Anilox roll is worn or dirty

Clean or replace anilox roll

Ink viscosity is too low

Add fresh ink to raise viscosity

Ink film thickness is too low

Increase ink film thickness by:

  1. Raising ink viscosity
  2. Reducing metering of the anilox roll
  3. Increasing anilox roll volume
  4. Adjusting ink for more transfer

Plate impression is incorrect

Adjust plate to substrate impression

Ink does not contain enough color

Consult with Sun Chemical Representative

Printing plate is too hard

Use plates with a softer durometer

Plates are glazed or dirty

Clean or replace plates

Substrate surface resists ink

Consult with Sun Chemical Representative

Ink formulation is incorrect

Consult with Sun Chemical Representative

Washboard Print

Consistent variations appear in the caliper of corrugated substrate, corresponding with the flute profile

Use a sheet that does not have washboarding / fluting

Plate impression is incorrect

Adjust plate to substrate impression

Substrate surface finish resists ink wetting and laydown

Consult with local Sun Chemical Representative for additives

Ink film is too thick for high hold out substrates

Reduce ink film thickness or use a more porous substrate

Ink film is too thin for stock and the flute tip to flute valley caliper variation

Improve corrugation process. Increase ink film thickness.Change ink formulation for more transfer

Ink viscosity is too low

Raise viscosity by adding fresh ink

Ink formulation is incorrect

Consult with local Sun Chemical Representative

Uneven Print Color

Ink metering system is out of adjustment or damaged

Check adjust, repair or replace press components

Uneven color appears across press

  1. Light to dark from roll parallel
  2. Streaks from grooved wiper roll
  3. Streaks from worn doctor blade
  4. Streaks from warped blade
  5. Streaks from damaged anilox roll
  6. Streaks from dirty anilox roll
  7. Streaks from low ink flow

Optimize colors across press by:

  1. Parallel all anilox/metering rolls/blades
  2. Replace wiper roll
  3. Replace doctor blade
  4. Reduce blade pressure or replace blade
  5. Replace anilox roll
  6. Clean anilox roll
  7. Increase ink flow through / across press

Uneven color appears through press variations

  1. Light to dark from low ink flow
  2. Loose plate or plate mount
  3. Roll bounce from gears or bearings

Optimize color through press by:

  1. Increasing ink flow
  2. Re-mount plates or mount to cylinder
  3. Check or repair press as required

Poor Trapping

First down ink is not dry due to improper ink or heavy ink film

Increase drying speed of the ink by:

  1. Reducing first down ink viscosity
  2. Reducing ink film with better metering
  3. Changing ink formulation for faster drying
  4. Decreasing machine speed
  5. Decreasing anilox volume

Second down ink is not covering due to low viscosity

Increase second down ink viscosity to higher than that of 1st down ink

Second down ink is not printing due to the ink drying too fast

Slow drying by adding glycol or increase press speed

Ink is not drying due to the high hold out of the substrate

Change substrate or reduce ink film thickness

Second down ink is not compatible with the first down ink

Use a transparent ink and switch trapping sequence

Second down ink is not printing due to too high or too low pH

Adjust pH or add fresh ink (non-pH stable inks only)

Print Striations

Ink is metered with a 2 roll system

Reduce ink on anilox roll by:

  1. Increasing metering roll pressure
  2. Using a harder durometer crown wipe roll
  3. Changing to doctor blade metering
  4. Changing ink formulation

Anilox rolls are plugged worn or dirty. Rolls have wide cell lands or coarse screens

Replace or clean anilox rollers. Change ink viscosity or formulations

Printing plate is too hard

Use plates with a softer durometer

Ink viscosity is too low

Raise ink viscosity by adding fresh ink

Printing plates are glazed

Clean or replace plates

Ink formulation is incorrect

Consult your local Sun Chemical Representative

Ink Smearing – Tracking

Ink is not dry due to ink film thickness or formulation

Increase drying speed of the ink by:

  1. Reducing ink viscosity
  2. Reducing ink film with better metering
  3. Changing ink formulation for faster drying
  4. Decreasing machine speed
  5. Decreasing anilox volume

Ink film applications are uneven on substrate

Adjust ink metering, print and anilox impressions, roll parallel & check plate level

Ink is not drying due to high hold out of substrate

Change substrate, reduce ink film thickness or increase drying capacity

On die cut or folding operations, anvil blankets are worn or rough cutting die pressure is excessive

  1. Folding belts are worn or slipping
  2. Guides, rails or bars are hitting print
  3. Stacker belts are hitting print

Optimize converting operations by replacing or trimming grinding anvil blankets, removing die rubber, replacing knives, reducing die pressure or replaclng anvil blankets

  1. Replace or adjust folding belts
  2. Adjust rails or bars to minimize impact
  3. Move or lift belts from print area

Ink formulation is incorrect

Consult your local Sun Chemical Representative

Mottled Print

Surface finish or caliper of substrate is inconsistent

Increase plate to substrate impression or switch to softer plates

Plate impression is incorrect

Adjust plate to substrate impression

Substrate surface finish or textured pattern appears on surface

Replace stock. Check with Sun Chemical Representative for additives

Ink viscosity too low

Raise viscosity by adding fresh ink

Too much water has been added to the ink causing it to be out of balance

Add fresh ink or replace ink in press pump

Anilox roller, wiper roll, or printing plate is dirty or damaged

Clean or replace rolls or plate

Ink in press is contaminated

Clean press station & replace ink

Ink formulation is incorrect

Check with Sun Chemical Representative

Ink is foaming

Add defoamer. Investigate and eliminate cause of foam

Ink pH is too low

Check and adjust pH (non-pH stable inks only)

Inconsistent Print Color

Color inconsistencies appear during press runs due to changes in viscosity

  1. Changes in substrate
  2. Additions to ink in press
  3. Foam

Optimize color consistency by monitoring and controlling viscosity

  1. Control substrate or adjust ink for stock
  2. Monitor, measure and control all materials added to ink at press side
  3. Add defoamer properly

Color inconsistencies appear between press runs due to changes in ink, substrate, run configurations, press conditions, suppliers, machine settings or speed

Optimize color consistency by monitoring, documenting and controlling critical variables of the printing process on each order thereby allowing reproducible print performance

Color inconsistencies appear between different press stations:

  1. Differences in applied ink film thickness between print stations
  2. Changes in ink, press conditions, plates, ink suppliers, operator measurement or machine settings

Optimize color consistency by:

  1. Adjusting or formulation ink to correspond to various station configurations such as anilox volume, cell count and condition, metering types, pressures and conditions
  2. Measure, document and understand differences, ensure that proper materials and procedures are used to minimize the effect of changes in the process

Color inconsistencies appear during press runs due to changes in pH

Optimize color consistency by monitoring and controlling ink pH (non-pH stable inks only)

Dirty Print – Halos

Entire image halos

Eliminate entire image halos by:

  1. Reducing plate to substrate impression
  2. Reducing anilox impression or checking plate level and mounting

Leading edge halos only

Eliminate leading edge halos by

  1. Reducing anilox pressure to plate
  2. Checking level and mounting

Plate wrap has distortion

Remount plate to fit cylinder tightly

Everything halos

  1. Plates are uneven, worn, cupped, glazed or
    mismatched (slugged)
  2. Ink film is too thick
  3. Printing plate is too hard
  4. Ink film applications are uneven due to machine or uneven plates

Eliminate all halos by:

  1. Leveling, building up, cleaning or replacing plates or entire mount
  2. Reduce ink film thickness by lowering viscosity, increasing ink metering effectiveness or decreasing anilox volume
  3. Use plates with a softer durometer
  4. Adjust ink metering, print and anilox impression, roll parallel or replace plates

Foaming

Too much air being introduced into ink

Check for leaking pump seals or hoses on the suction side, repair as required

Pump pressure is excessive causing splashing and aeration

Reduce pump pressure to minimum required (Use pump volume, not pressure)

Agitation of ink is excessive causing splashing and aeration

Reduce pump or mixer speed to the minimum required and keep ink return lines submerged

Poor sealing of doctor blade assembly

Replace blades frequently. Adjust chamber for wipe and sealing. Adjust pumping to keep chamber full.

Too much water is being added to the ink

Raise ink viscosity by adding fresh ink

Ink viscosity too high

Lower ink viscosity to release trapped foam

Ink formulation is incorrect

Consult your local Sun Chemical Representative

Excessive foam

Spray a mist of Sun Chemical defoamer over the surface of the bubbles to break foam formation