Trouble Shooting Guide

 

 

 

The ink formula will determine the amount of maintenance on press; the less maintenance required from inks, the less need for trouble shooting. With that said, inks are formulated to achieve specific results. To lower the cost of an ink, the formulators options are limited. To increase resistance properties the formulators need to add more resistance products.

Defect

Indicator

Possible Cause

Solution


Adhesion

Poor tape test

Ink Flaking off

(poor crinkle)

Ink rubbing off
Insufficient Treatment
Level

Ink not drying between
traps

Substrate may be old or
contaminated

Working ink formulation
for the job
Check and adjust treatment level

Increase heat and air flow

Check Surface Substrate

Use correct ink formulation

Bleeding

Discoloration of trapped
colors (White particularly)

Color migrating
in a dried
ink film

Ink Discoloring
or wicking,
not holding up to
the final application
(Chemical Resistance)

Ink not drying
between traps

Poor pigment selection
for the application

Adhesives not fully
dried or fully cured

Increase heat and
air flow Use correct
ink formulation

Adjust Lamps
or reduce press speed
to improve cure speed

Blocking


Ink transferring
to the back side of web

Not able to unroll web-stuck
together in the roll


Ink not drying
between traps

Dyne treatment
level to high

Excessive web
tension or
PH enhancer

Rewound at a
high temperature


Increase heat
and air flow

Check treated
surface, 38-40
dyne is sufficient

Reduce web
tension

Use fresh ink

Use a chill roll possible

Chatter


Parallel lines
of misprint


Gear bottoming
below pitch line

Increase heat
and air flow

Check treated
surface, 38-40
dyne is sufficient

Reduce web
tension

Use fresh ink

Use a chill roll possible

Colors too strong


Color hits the
stronger
Pantone color

(Reds to yellow)
(Blues to red)
(Yellows to red)

Anilox is in
better shape then the
one used in the
previous run

Higher volume anilox
then previous
run/Strong color
match/viscosity
too high

First adjust Viscosity, change anilox BCM voume if possible

Then reduce
using Transparent
white

Adjust to use
correct ink
formulation

Colors too weak


Color hits the
weaker
Pantone color

(Reds too Blue)
(Blues too Green)
-washed out


Ink Viscosity
to low

Dirty anilox,
lower anilox
than previous run

Weak ink

Fresh ink is needed, change anilox BCM voume if possible

Then increase color
strength using
high strength toners
or stronger fresh ink

Adjust to use
correct proper
ink formulation.

Dot Gain Fill-in or
bridg-ing/feathering
(Dirty Print)


Printed dot
increasing in
size - bridging one
letter to another
or letters filling
in basic dirty print


Excessive ink
volume, Dot dipping,
plate Swelling

Low ink viscosity
v.s press speeds

Viscosity of
the ink is heavy

To much Impression

Ink printing
dirty - not rewetting properly

Maintain a 4 to 1
ratio anilox line
count to screen count.
150 line screen - 600 line anilox

Adjust viscosity,
use fresh ink

Reset impression,
Use a PH adjuster.

Drying To fast


Dirty Print -
Fill in -
Bridging

Ink Drying on Plates

Poor transfer

Loss of PH Level

Air blowing
on to the plates

Ink formulated
for high speed printing

Use a PH adjuster
to increase rewetting
and retard drying
(AVPH-10)

Re-adjust
any unwanted air flow;
fan , blowers

Use correct ink formulation

Drying to slow


Picking

Blocking

Offsetting

Ghosting

Over use of
print enhancers
(AVPH-10)

Excessive ink
film thickness

Poor air circulation - heat
to low or clogged exhaust

Ink formulation
needs to be adjusted
to higher speeds

Replace existing
ink with fresh product

Reduce anilox
volume

Increase heat
and air flow

Use correct in
formulation

Reduce press speed
and maintain
balanced air flow

Feathering


Irregular string-like
edges around print
often on trailing
edges

Improper pressure
between ink
transfer roll and
plate

Ink drying on the
plate or anilox

Improper setting of
ink roller nip

Improper ink rollers

Set proper pressure
between ink transfer
roll and plate

Film Curl


Curl over on edges cellophane

Curl toward coated side

Curl away from coated side

Excessive moisture. Introduce
heat edges. Use heat guns

Lack of moisture. Introduce moisture
to edges. Use moist sponge

Flat Process


Lack of contrast

Poor molds and plates

Prepare molds to proper floor

Foaming


Excessive ink
foam in fountain

Ghosting

Loss of image on
the ends of channeled
blade systems

Ink viscosity too heavy

Old or reworked
inks in fountain

High press speeds
result-ing
in high shear

High agitation from ink pump

Adjust viscosity

Use a defoaming additive
(AVDF-78) or
(AVDF-16 - surface
active for
high shear)

Reduce pump
velocity or
agitation

Ghosting


A faint image of a
plate portion within
a printed solid

Ink viscosity too heavy

Old or reworked
inks in fountain

High press speeds
result-ing
in high shear

High agitation from ink pump

Adjust viscosity

Use a defoaming additive
(AVDF-78) or
(AVDF-16 - surface
active for
high shear)

Reduce pump
velocity or
agitation

Hickeys or Darting


Random imperfections
in the print.

Specs in the print
with a white halo
or a darting effect

Paper dust or other
par-ticulates interfering
with impression

Excessive impression

Sticky back to
thin or to firm

Ink Viscosity to High

Filter inks
Reduce any static
electricity using
garland of foil

Reset Impression

Remount plates
with proper sticky back

Adjust viscosity

Ink Mottling


Irregular appearance
in solid areas

Squiggly lines

Ink Viscosity to low

Poor treatment level
of substrate or
contaminated surface

Replace existing ink
with fresh product
and check film surface

Odor


Undesirable odor
in Printed substrate

Retained solvents

Balance solvents and
check for proper solvent

Check dryer efficiency
and temperature

Increase between
color drying

Offset or Set-Off


Transfer of ink
to opposite side of
material than that on
which it was printed

Ink not dry at rewind

Use faster solvents. Check between
color and final dryers for
obstructions and adequate
air and temperature

Reduce ink viscosity to minimum acceptable;
increase wipe between the
fountain and anilox rolls

Pick-off/Ink


First down ink
transferring to
Subsequent plates

First color too slow

Second color too fast

Second-down color too
high in viscosity

Add fast solvent to first
color; increase between-color
dryer temperature

Add slow solvent to
overprinting color. Check dryer

Increase press operating
speed and/or reduce viscosity
of second-down color

Pin Holing


Imperfections in the Print

Specs in Print -
Poor lay down

Ink viscosity to thin

Old or reworked
inks in fountain

Poor treatment of
substrate or contaminated surface

Adjust viscosity

Use a leveling
additive (AVPS-5)
and/or defoamer (AVDF-78)

Check surface
Dyne level 38-40

Check for oil or
contami-nants
on substrate (Foil)

Plate swelling


Dimensionally larger
softer than when
mounted on cylinder

Ink or solvents
not compatible
with printing plates

Check ink and
solvents being used
with you inkmaker
and plate supplier

Poor Ink Transfer


Insufficient ink
being applied
to stock

Ink reduced too much

Ink drying on plates

Surface of stock not
receptive to ink

Rebuild tack and color strength

See defect "Drying too fast"

Verify ink formulation
with ink supplier

Screening


A definite pattern
of small holes
appearing in
surface of solid

Ink drying too
fast on anilox
roll and failing
to transfer
properly to
printing plate

Use fountain covers

Examine wear condition
of anilox lands.
Replace with new or
reengraved anilox

Skip Print


Areas of plate
failing to print

Poor plates or makeready

Impressions set
to light

Check impressions
to determine accuracy
of plates

Readjust impression
settings