All posts by sterryInk

Inadequate Drying

Ink is taking up too much water

Check ink/water balance.  Run proper amount of ink and water

Rollers are not properly conditioned or set

Thoroughly condition or reset the roller system.  (Improperly set or poorly conditioned rollers promote emulsification of ink.)

Fountain solution pH or conductivity is wrong

Adjust to manufacturer’s specifications

Heatset solvent range for proper volatilization is too high

Consult your Sun Chemical representative

Excessive ink thickness is being run

Consult your Sun Chemical representative about stronger ink

Web exit temperature is too low

Increase web exit temperature

Dryer temperatures are too high, inhibiting the ability of chill rolls to cool web efficiently

Decrease web exit temperature and check chill roll  efficiency

Marking is visible on chills or delivery equipment

Check web exit temperature from dryer and chill rolls.  Check cooling efficiency of chill roll system

Gloss

Print gloss is too low

Run a higher tack ink

Use a higher gloss ink

Reduce dryer temperature to minimum settings

Check chill roll system

Increase ink film thickness

Minimize water settings

Consult your Sun Chemical representative

Dot Gain

Rollers and pressures are improperly set

Reset rollers and pressures

Rollers or blankets are too soft

Condition or replace rollers or blankets

Ink is low in viscosity and/or tack

Consult your Sun Chemical representative

Ink color strength is too weak; ink film is too heavy

Consult your Sun Chemical representative

Ink is too receptive to water

Consult your Sun Chemical representative

Blankets are packed improperly, or too much pressure exists

Check packaging and pressure

Ink is piling

Consult piling section of this guide

Plate is poorly desensitized

Consult your pre-press department

Dampening system is dirty

Clean dampening system

Fountain solution pH or conductivity is out of balance

Adjust pH and conductivity to manufacturer’s  specifications

Slurring or doubling occurs in halftone

Check cylinder pressures, blanket tension and roller slip-page.  Check mechanical operation of unit

Plate is improperly exposed and developed

Consult your pre-press department

Chill Roll Condensation

Streaks appear on web or signatures. This is caused by ink resoftening due to solvent condensation on chill rolls

Check dryer and/or chill roll temperature. Use inks with lower boiling point solvents if possible. Consult suppliers of dryer, chill rolls and inks as necessary

Dryer temperature is too high, inhibiting the ability of chill rolls to cool web efficiently

Decrease web exit temperature

Marking appears on chills or delivery equipment

Check web temperature from dryer and chill rolls. Check cooling efficiency of chill roll system

Excessive ink film thickness is being run

Consult your Sun Chemical representative about stronger ink formulations

Blister

Dryer temperature is running too high

Reduce dryer temperature. Consult your Sun Chemical representative about ink drying speed

Moisture content of paper is too high

Run different paper. Run different paper lot or position number

Too heavy an ink film is being run

Consult your Sun Chemical representative about a stronger ink formulation

Poor Trapping – Process Inks

Ink/water is not in balance

Achieve and maintain proper ink/water balance Running a minimum amount of ink and water is always preferable

Ink film thickness may be wrong

Check that inks are running at correct density levels

Paper may have low absorption capacity

The lower the absorption of the paper, the slower the inks will set leading to less efficient trapping

Poor Transfer of Ink

Rollers are improperly or inadequately cleaned and glazed

Thoroughly clean rollers with a good quality glaze remover. After removing all ink with wash-up solvent, then apply hot water to rollers. This will remove gum glaze that is not soluble in standard solvent based wash-ups

Calcium build-up on roller surfaces

After normal wash-up, follow with a hot water / white vinegar wash (2:1) to remove calcium deposits

Rollers are improperly set or are swollen or distorted

Adjust roller settings or check roller surface condition

Indiscriminate use of wetting agents; gum and gum substitutes in fountain solution

Control use of fountain solution and additives which can have adverse effects on the rollers

Roller temperatures not warm enough

Make sure form rollers are 72°-80°F (22°-26°C) for optimum performance

Tinting / Toning / Scumming

Fountain solution condition

Check condition of fountain solution. If dirty and old, replenish with fresh at recommended dosages and correct temperature

Roller durometer or roller settings are out of specification

Check roller durometers and settings according to press manufacture’s recommendations

Too much pressure exists between plate and blanket

Check and correct if necessary

Temp of roller train and water pan

Form rollers should be close to 75°F (23°C) and water pan 65°F (18°C)

Improperly over packed cylinders – too much squeeze

Correct packing and re-torque blanket to press manufacturer’s specifications

Ink or dampener rollers are set too tight

Check and reset rollers to press manufacturer’s specifications

Blanket is glazed

Remove glaze or change blanket

Fountain solution is out of balance

Drain pans and tanks. Refill with fresh fountain solution at correct pH, conductivity, and Brix level

Prolonged use of oily wash-up solution

Change to fresh wash-up solution

Roller train temperature is too hot

Maintain forms at 72°-80°F (22°-26°C) surface temperature

Fountain solution is too hot in pans

Maintain fountain solution temperature in press pans at 65°F (18°C)

Ink roller durometers are either too soft or too hard

Check durometer, setting, and condition of ink rollers

Stripping

Rollers too hard and out of specification

Check durometers and replace if necessary

Excessive calcium, gum and other material in roller train

Apply a calcium rinse or hot water/white vinegar (2:1) rinse

Roller train and fountain solution too cold

Set rollers to 72°-80°F (22°-26°C) and water pan to 65°F (18°C)

Fountain solution too mild

Ensure chemistry has enough etch and alcohol substitute per manufacturer’s recommendations