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196 FLEXOGRAPHY: PRINCIPLES & PRACTICES

appropriate print stations.

Wide-web plate cylinders are extremely

heavy, thus requiring the operator to use

carts and/or hoists for the safe handling of

cylinders (Figure ). Operators must use

caution when loading print cylinders into the

press to prevent the plate surfaces from

being bumped and damaged. After all the

cylinders are loaded into place, bearing caps

must be installed and tightened to keep the

roll stable during the pressrun (Figure ).

Ink the Print Stations

The next step in the setup procedure is to

ink up the print stations. The following pro-

cedure details a typical print station inking:

1. Double check the color in the ink con-

tainer to verify that it is the color to be

placed in that print station.

2. Circulate the ink in the ink pump

through the supply hose back into the

pump to remove air from the system.

3. If an ink pan is being used, align the

ink pan and lock down the hold down

mechanism. Ensure that the pan will

not rub on the ends of any rolls or the

surface of the plate cylinder.

4. Connect the return hoses from the ink

pan to the ink pump, making sure they

are routed around any moving parts.

With water-based inks, return hoses

must be slightly submerged in the ink

of the ink pumping unit to help avoid

foaming.

5. Connect the supply hose from the

pump to the ink distribution system.

6. Pump the ink into the distribution sys-

tem.

7. After the ink has been pumping for a

time, take the viscosity (pH and vis-

cosity for water-based inks) to ensure

that the ink is at its running parame-

ters. If the ink is not at its running para-

meters, it should be adjusted and

rechecked to meet specifications be-

fore the pressrun begins.

Set the Fountain Roll

and/or Doctor Blade

Once the ink is in the fountain and is with-

in its recommended running pH and viscos-

ity parameters, the anilox roll may be inked.

When using a two-roll system, the fountain

roll is adjusted to squeeze against the anilox

roll. Once the press is started, the rubber roll

is adjusted so that it evenly squeezes the ink

off the anilox using the minimum amount of

pressure. This pressure setting is checked by

backing the fountain roll off until the operator

can see the nip flood with ink. Then the oper-

ator squeezes back in with both sides of the

rubber roll, making sure they are even, until

the flooding on the surface goes away. By

doing this several times, the ink wipe is set.

Due to the heavy

weight of wide-web

plate cylinders, most

operations use carts

for the safe handling of

cylinders.

When installed and

tightened, bearing caps

keep the roll stable

during the pressrun.

pression slightly so the plate comes

into contact with the web.

2. Turn in the anilox-to-plate adjustment

to begin inking the plate. While looking

at the print on the web, make adjust-

ments to the impression and ink set-

tings until there is a clear print with no

images missing.

3. Similar to the setting of the rubber roll

or doctor blade, back in and out on the

settings to achieve ink and impression

settings with the minimum amount of

pressure.

4. Set the remaining ink and impression

settings, working backward to each

print station in order from last to first.

5. After all the settings are complete for

each print station, adjust for color-to-

color registration. Start with the first

station (front of the press) and set reg-

ister for each station in order.

6. Once all the colors for the job are in

to-die registration. Register the die cut-

ter and slitter to the printed image. In

all flexo press settings, it is important

to use the minimum amount of pres-

sure to do the job.

Check Colors to Standard

Once the press is set up and all settings are

PRESSROOM PRACTICES 197

A chambered doctor-

blade assembly should

be installed before the

pump is turned on. The

ink wipe should be set

in the same manner as

a single blade, and

there is no rubber roll

to set.

On some wide-web presses, a doctor blade

is used in conjunction with the rubber foun-

tain roll. In this case the doctor blade must

be set to meter the anilox roll.

When setting a station with a doctor blade,

the fountain roll pressure should be set a lit-

tle loose. This setting allows for extra ink to

go through to the doctor blade where it is

metered off. The doctor blade assembly is

set into its holder and then slowly tightened

down until it touches the anilox. As the

blade is tightened to the anilox, the operator

will notice that the ink will meter from the

center of the anilox roll outward to the ends.

When the ink is metered off the ends of the

anilox roll, the wipe is set. Similar to the pro-

cedure for setting fountain roll pressure, the

doctor blade should be backed out and

brought back in to the anilox several times

in order to set the wipe with the minimum

amount of pressure. Overtightening the doc-

tor blade can cause the blade to fold under

the pressure, causing the ink to dry due to

the friction and heat buildup behind the

blade. If ink drying occurs, the dried ink pig-

ments can cause damage to the anilox roll.

Once the ink is metered correctly, cover

the fountains with the ink-fountains covers.

The covers reduce the amount of amine or

solvent that evaporates out of the ink to help

keep the ink more stable during the pressrun.

If the press is equipped with a chambered

doctor-blade assembly, the assembly is

installed before the pump is turned on. The

ink wipe should be set in the same manner

as a single blade, and there is no rubber roll

to set (Figure ).

Set Impression,

Inking, and Registration

The following procedure details a typical

impression, inking and registration setup:

1. With the press running at a slow speed,

start with the last color to be printed

and achieve the correct impression

and ink settings. Turn down the im-

Plate

Cylinder

Anilox Roll

Reservoir

Ink “Out”

Return

Ink “In”

Supply

Containing

Doctor Blade

Metering

Doctor Blade

198 FLEXOGRAPHY: PRINCIPLES & PRACTICES

complete, the printing must be checked for

accuracy against a color standard that has

been approved by the customer in the design

stage of the job. A color standard may be a

previously printed sample, a Pantone

sample, an ink drawdown or a spectropho-

tometer reading.

All visual color matching should take

place in a viewing booth designed for this

purpose. This type of booth provides a stan-

dardized light source with a neutral gray

background to check color, eliminating the

color variations during the color-matching

process caused by lighting conditions.

A sample of the print should be compared

to the color standard to ensure that the

printed job meets the customer’s require-

ments. The operator should check to make

sure the color is printing at the correct den-

sity (lightness and darkness) either visually

or with the use of a densitometer. If the color

is not printing at the correct density, the

anilox may be changed to achieve a density

match with the standard. This change is

especially useful when working with ultravi-

olet inks. For slight density changes that are

needed when working with conventional

inks, the ink viscosity may be changed by

adding solvent, or the ink may be extended

to reach the color standard.

The ink hue should also be checked visu-

ally in a light booth or with the aid of a spec-

trophotometer. If changes in hue are needed,

the operator should add the correct ink bases

to reach the color standard. All of the infor-

mation from the color matching process

should be documented so the job can be

reprinted without additional downtime.

Approval Form

Many companies use a checklist approval

form that is filled out after the job has been

set up and approved (Figure ). This form

helps ensure that all the details for printing

the job have been covered and that the job

matches the specifications on the job jacket.

The goal in setting up any wide-web flexo-

graphic press is to minimize the preparation

time to get the job running quickly. This tim-

ing requires efficient teamwork between all

production personnel. Operators must antic-

ipate the next task to be completed during

the setup to reduce downtime. A press will

only make money when it is in production.

Setup time is expensive.

PRESSRUN PROCEDURES

Once the press is running, there are quite a

few other areas that must be checked regu-

larly. Here’s what needs to be done next…

Ink Viscosity and pH

Maintaining viscosity, or pH and viscosity

in the case of water-based inks, is essential

for producing consistent print throughout

the production run. If an ink is color-

matched at a 25-second viscosity, a higher

viscosity will make the color print darker. A

higher viscosity occurs because the solvent

or amines evaporate out of the ink during

the pressrun, causing the customer’s prod-

uct to become inconsistent as the run pro-

gresses. In order to maintain the same den-

sity of print throughout the pressrun, viscos-

ity (solvent based inks), or pH and viscosity

(water-based inks), must be maintained.

When doctor blades or chamber blade sys-

tems are used, high viscosity inks will cause

ink starvation by not reloading the anilox

cells. The print will not be consistent and the

color variations in the product will not be

acceptable to the customer. If the ink is run-

ning at a lower viscosity than the viscosity of

the color match, the color will get lighter. If

the viscosity gets too close to the minimum

running viscosity for that ink, printing

defects may occur.

Controlling Ink Viscosity and pH. Viscosity

Pantone, PMS and the Pantone Matching System are trademarks of Pantone,

Inc.

checks should be completed every 10 to 15

minutes when using solvent-based inks.

When using water-based inks, pH and vis-

cosity should be checked every 30 minutes.

It is important to check pH first, followed by

viscosity, when using water-based inks

because the viscosity is affected by the pH

level. Solvent inks require more frequent

checks of viscosity since the solvent evapo-

rates quickly and is more unstable than the

water in water-based inks.

To control an ink’s viscosity, small amounts

of a reducer should be added. The viscosity

level should never get so high that it takes

more than a pint of reducer to return the vis-

cosity to the correct level. Careful control of

ink viscosity (pH and viscosity for water-

based inks) results in consistent color and

uniform ink flow throughout the job run.

To control solvent-based ink viscosity, sol-

vent reducer is added during the pressrun.

The make-up solvent should have a slightly

PRESSROOM PRACTICES 199

A checklist approval

form should be filled

out after setup has

been completed and

approved.

SUPERVISOROPERATOR

I HAVE MADE ALL THE APPLICABLE CHECKS AND APPROVE THIS ORDER FOR START-UP.

COMMENTS:

BOXES

LABELING

STANDARD

OPERATION

INK

SPECIAL SIZE

SPECIAL

REWINDER

SHRINKWRAPPING

SHIPPING FROM PRESS

FANFOLDING

PADDING

TRIMMER

OTHER

TIPPING

WRITE ON

PRIMER

FACE COPY—WATER BASED

FACE COPY—SOLvENT BASED

BACK COPY—WATER BASED

BACK COPY—SOLVENT BASED

COPY REGISTRATION REWIND

READ

QUALITY LEVEL

COLOR SEPARATIONS

IMPRESSION

NO SPLICES SIZE OF FOLD

PINFEED HOLE ALIGNMENT

UV CURING

VARNISH

TAPE TEST RUB TEST

LIST PMS COLORS

POSITION

QUALITY

MISC. MACHINE COUNT:

% OVERRUN

FANFOLD FOLDING STRAIGHT

CUTTING CLEAN

POSITION OF FOLD

PERF TEARS CORRECTLY (NOT TOO HARD/NOT TOO EASY)

HINGE FOLDING CORRECTLY

SPLICES REQUIRED

DIE CUTS HAND APPLIED

REGISTRATION

PERFED

CUTTING CLEAN

SINGLES LAY FLAT

MACHINE APPLIED

DIE CUT

SCORED

LINER TEST

JOG EVEN SIZE

MULTIWEB

OR COUPON

CONSTRUCTION TYPE

BASE STOCK

PROPER RELEASE (NOT TOO TIGHT/NOT TOO EASY)

GLUE

TOP STOCK

SIZE JACKET

MOCK-UP

DIE NO.

LINER SIZE

CARD CURL

BUTT CUT

SLITS

HOLES

SHEETED

MARGINAL PUNCHES

TEAR TAB

SCRATCH OFF

UPC SCAN

CUSTOMER

DATE

STOCK

JOB NO.

PRESS NO.

INV. NO.

PRESS APPROVAL START-UP SHEET

ITEM NO.

SIZE

200 FLEXOGRAPHY: PRINCIPLES & PRACTICES

higher percentage of the fast solvent than the

solvent in the system. For example, if the ink

system is 10% normal propyl acetate and 90%

normal propyl alcohol, the acetate is the fast

solvent and will tend to evaporate faster than

the alcohol, which is the slow solvent in the

blend. The make-up solvent should be a slight-

ly higher concentration of acetate to keep the

ink stable, as well as maintain the viscosity

during longer runs.

To control viscosity in water-based ink

systems, water and amine are used. A stabi-

lizing varnish may also be used. Stabilizing

varnish is a water and amine combination

that has been premixed to the correct per-

centages for the ink system being used. An

addition of stabilizing varnish should lower

the ink viscosity while maintaining the pH of

the ink. Water alone will reduce the viscosi-

ty, but it may also reduce pH, which causes

other print problems.

Many wide-web presses used for long runs

are equipped with automatic viscosity con-

trollers. Viscosity controllers dispense a pre-

determined amount of solvent into the ink

system to keep the ink stable throughout the

pressrun. It is important, however, to check

the viscosity manually (Figure ) when

using these controllers to ensure that the

they are working properly.

Water-based inks should be run in a spe-

cific pH range to keep them working effi-

ciently. The pH range varies by ink manufac-

turer and the requirements for the job.

Generally, water-based inks are in the pH

range of 8.0 to 9.3. When the pH of a water-

based ink falls too low, the ink will begin to

body and thicken, eventually causing rewet-

ting problems and dirty printing. If the pH is

too high, the viscosity of the ink will be too

low, causing drying or blocking problems.

Color variations and print defects caused by

pH levels can be eliminated by maintaining

pH within its recommended range.

A pH meter is the instrument used to read

pH levels (Figure ). These instruments

should be calibrated to a buffer solution with

a known pH on a regular basis. Similar to vis-

cosity controllers, many presses have auto-

matic pH controllers that check pH and add

predetermined amounts of stabilizer or amine

to maintain the proper pH level in the ink.

Operators should double-check these devices

by reading the pH manually to guarantee they

are working properly during the run.

Adding Ink to the Fountain

During longer runs, the press operator

may be required to add ink to the fountain or

pump. This requires specific attention to

detail. The following procedure details a typ-

ical ink addition procedure:

1. Double-check the ink to be added for

correct color. Do not assume that an

One way of checking

viscosity is by timing

the ink flow through a

Zahn cup.

When using water-

based inks, it is crucial

to maintain a pH in the

range of 8.0 to 9.3.

ink container is marked correctly.

2. Adjust viscosity (and pH for water-

based inks), of the ink to be added.

Solvent-based ink to be added to the

fountain should be thinned to a vis-

cosity that is two to four seconds high-

er than the ink in the fountain.

Viscosity of water-based inks should

be five to 10 seconds higher than the

ink in the fountain. Agitation of the ink

will cause a viscosity drop of three to

five seconds.

3. Add only enough ink to bring the level

back to the optimum level.

The optimum level should be determined

before the production run. It is based on the

amount of ink coverage for a given color,

which depends on the ink coverage for the

job being printed. The big print areas that use

more ink will require the ink pans to be filled

more often than those that use little ink. Add

fresh ink each hour to a low coverage area

rather than filling up the fountain and adding

only solvent or stabilizer for the whole shift.

Fresh ink helps maintain the correct balance

between colorant, resin and solvent (water

and amine for water-based ink).

Ink loses printability and flow characteris-

tics if only solvent (water and amine for

water-based inks) is added over a period of

time. This loss is due to the depletion of the

colorant and the resin in the ink.

For the ink to work properly, and to

avoid printability problems, press opera-

tors must know the following about the

inks they are using:

• upper and lower working viscosity

limits;

• solvents and additives to be used;

• range of pH for water inks; and

• maximum pigment load the ink can

handle.

By maintaining the proper percentages of

ink components, the color will be more con-

sistent and fewer print problems will occur.

Inspection and Quality Checks

During a pressrun, the operator should

make ongoing inspections of the press and

the job being printed. The following items

are typical pressrun checks:

• Listen to the press for any unusual noises

that may indicate a mechanical problem.

• Double-check the ink level in the foun-

tain or pumping unit. When using a

pump, check the ink flow to the pan.

• Ensure that the low roll indicator is on.

Prepare for roll changes and splices.

• Monitor print quality with a strobe light,

video monitor or the naked eye.

During the pressrun, print registration may

change and could be caused by the following:

• incorrect web tension between in-feed

and out-feed ends of the press;

• rewind roll tension is too high;

• web splices offsetting the web;

• rolls of stock varying from roll to roll;

• baggy edges on the rolls of stock mov-

ing the web to one side; and

• web thickness and adhesive coating

vary on rolls.

Inspecting a print sample is the most accu-

rate check of print quality. Operators should

not rely on checking print quality on the mov-

ing web alone. Samples of the printed product

must be checked visually with a magnifier for

poor registration, poor ink lay, color drifts,

color match, and ink adhesion or cure. The

operator should be looking for variations in:

• print registration (Figure );

• the cleanliness and sharpness of the

print;

• ink or impression misses;

• ink picking;

• flaws due to plate lift, lint or other

causes; and

• print quality.

Printed samples should be checked

against the color standard on an ongoing

PRESSROOM PRACTICES 201

202 FLEXOGRAPHY: PRINCIPLES & PRACTICES

basis to ensure consistency throughout the

run. If a densitometer or spectrophotometer

is being used when the job is set up, and dur-

ing the initial color match, it should be used

during the pressrun. Samples from each

printed roll should be evaluated.

Color-drift checks are performed by laying

consecutive samples in a row on a white

background (Figure ).

Ink-adhesion tests are performed by

putting cellophane tape firmly onto the

printed image and pulling slowly upward

from the image for half of the length of the

tape. The remaining tape is pulled quickly off

the other half. The tape is then examined to

see if it is free of ink.

Solvent-based inks typically have a dyne

level of about 23. Water-based inks have a

dyne level of around 30 or higher depending

on the surfactants being used. In order to

have good ink transfer and adhesion, the

film being printed should have a dyne level

approximately 10 levels higher than the ink

being used.

Flexographic printing on film generally re-

quires that the film be treated, which changes

the surface of the substrate so that the ink can

adhere. The amount of treatment on a film is

measured in dynes with a special solution

using pens or liquids (Figures ).

Quality Awareness

The flexographic printing process requires

consistent and careful monitoring during the

pressrun. There are no assurances that a job

printing well presently will be doing so in five

A magnifier can be

used to check for

errors in print

registration.

A color-drift check

is accomplished by

placing consecutive

samples in a row on a

white background.

Conducting a dyne test

with a pen.

Conducting a dyne test

with liquid.

or 10 minutes. Proper pressrun procedures

are the mainstream of top quality finished

products. Press operators must learn and per-

form all pressrun procedures well. Quality

checks should be performed regularly and the

results should be documented. These results

should be kept for a period no less than the

life of the product produced. Quality is the

result of conscious effort by the operator.

Preparing for the Next Job

Preparing for an upcoming job is common-

ly done while the current job is running.

Preparation generally requires assembly of

the necessary plate rolls, substrates, inks,

cores and tooling. The press operator and

assistants should perform the following acti-

vities in preparation for the next job:

• review information in the next job jacket;

• plan print station wash-ups;

• note required inks and colors;

• note colors and anilox rolls in current

use that may be needed; and

• gather all materials and supplies in

advance.

CLEANUP PROCEDURES

Most jobs require some degree of cleanup

upon the completion of a run. Inks for the

next run are often different, which requires

that the press equipment be washed. Since

the press is profitable only when it is in pro-

duction, an efficient cleanup program is

needed. A correct wash-up procedure mini-

mizes downtime between jobs and main-

tains the press in good working condition.

Cleanup procedures vary by company and

brand of equipment.

Before the actual cleanup, the operator

should double-check the next order to deter-

mine if any inks can remain for the next job.

Preliminary Cleanup Steps

The following preliminary steps should be

taken before starting the cleanup process:

1. Cover the lower decks with scrap

material to protect them from ink drips

caused by washing an upper deck.

2. Position ladders needed to reach the

upper decks.

3. Move ink decks away from the impres-

sion cylinder if appropriate.

4. Fill a container with wash-up solution

and place it near the print station.

5. Get an empty container to catch wash-

up solution coming from the ink pan.

In an effort to conserve ink, the operator

should lower the ink pan and squeegee the ink

down the ink return hose and into the ink

pump before wash-up begins. The return hose

should be switched to the wash-up container,

at which point the clean up process begins.

Two-roll Station Cleanup

The following procedure details a typical

cleanup for a two roll system:

1. Turn off the ink pump and disconnect

the power supply to stop the flow of ink.

2. Pump cleaning solution through the

entire system. This pumping makes the

entire system easier to clean.

3. Remove the ink supply hose from the

deck.

4. Stop the rotation of the rubber roll.

5. Release the pressure between the rub-

ber roll and the anilox roll.

6. Move the ink return hose from the ink

pump to the wash-up container.

7. Reset pressure between the anilox and

rubber roll and restart their rotation.

8. Flood the anilox and rubber roll with

wash-up solution as they slowly turn.

The solution will remove ink from the

surface of the rolls. Thorough cleaning

may require several passes over the rolls

with fresh solution to remove the ink.

9. Release the pressure between the ani-

lox roll and rubber roll on one end only.

10. Wipe the anilox roll. Begin on the side

with the released pressure. Use a folded

PRESSROOM PRACTICES 203

204 FLEXOGRAPHY: PRINCIPLES & PRACTICES

rag or shop towel soaked with cleaning

solution. If water-based ink is being

washed up, it is best to keep the foun-

tain roll and anilox roll wet until the ink

is washed off, otherwise the dried ink

will be difficult to clean later.

11. When the end of the roll is reached,

release the pressure on the remaining

end. Finish wiping the anilox roll.

12. Clean the rubber roll the same way as

the anilox roll.

13. Stop the rotation of the rubber roll and

thoroughly clean both ends of the

anilox and rubber roll.

14. Go over each roll with propyl alcohol to

remove any residue left from the soap

used to clean water-based inks.

The print station of a two-roll system con-

tains pinch points between various rolls.

These pinch points are referred to as

inward nips (Figure ). The person clean-

ing the print station must use extreme care

in this area because it is easy to catch a rag

or finger in the nip.

Chamber-bladed Station Cleanup

The following procedure details a typical

cleanup for a chamber blade system:

1. Disengage the doctor blade assembly

from the anilox.

2. Lock the blade assembly into the clean-

up position using the appropriate safe-

ty mechanism.

3. Clean the anilox roll by passing a fold-

ed clean rag or towel soaked in cleanup

solution along the entire face of the roll

as it rotates.

4. Turn off the anilox drive motor and

wash both ends of the anilox thor-

oughly.

5. Carefully remove any ink buildup from

the sides of the anilox.

6. Make a final pass with a clean damp

rag. Follow with a clean dry rag to fin-

ish the cleaning process.

Extreme caution is required when cleaning

the anilox roll when a doctor blade is being

used. The cleanup person must be aware of

the location of the blade to avoid accidental

bumping while cleaning. Doctor blades are

extremely sharp and can cause severe injury.

Cleaning the Plates

When cleaning solvent-based ink off of the

plates, the solvent blend for the ink system

should be used. Excessive amounts of

acetate should be avoided, as it will damage

the plates. When cleaning water-based ink off

of plates, a cleanup soap should be used

(Figure ). A soft-bristled brush may be

used to scrub the plate clean after the solvent

or soap is applied to the plate. The plates

The area where two

rolls meet is known as

a nip zone. Care must

be taken to avoid

catching fingers or

rags in nip zones

during cleaning.

Use extreme care when

cleaning the plates.

Impression

Cylinder

Plate Cylinder

Fountain Roll

Anilox Roll

Nip Roll

Danger

Zone

should be blotted dry with a rag or absorbent

towel. Avoid rubbing the plate, as this may

damage the plate image.

After the plate is clean, ink on the cylin-

ders and gears should be removed. The oper-

ator should make note of any damaged or

worn plates and identify any defects so new

plates can be ordered for the next run of that

job. A bad cylinder or gear should be report-

ed so it can be repaired or replaced.

Doctor-blade Assembly Cleanup

Cleaning the doctor-blade assembly re-

quires direct contact with the doctor blade.

Cut-resistant gloves should be worn to mini-

mize the risk of injury. In some cases, the

blade assembly is removed from the press for

cleanup. The following procedure details a

typical cleanup for a doctor blade assembly:

1. Soak a shop rag or towel in cleaning

solution and wipe the inside and out-

side of the assembly. Also wipe both

sides of the blade. Light pressure will

reduce the chance of the blade cutting

through the rag.

2. Check the condition of the doctor blade.

Carefully remove blades that show

excessive wear or damage. Dispose of

blades in a designated container.

3. Continue cleaning the blade assembly

with a soaked rag until most of the ink

on the assembly is gone. Complete a

final pass with a clean damp rag to

remove any last traces of ink.

Operators must remember that the anilox

roll is already clean. Splatters that land on

the roll surface from cleaning the assembly

must be removed.

Replacing a Doctor Blade

If a worn or damaged doctor blade must

be replaced, the blade assembly may need to

be removed from the station. The following

procedure details replacing the doctor

blade:

1. Loosen and/or remove the hold-down

bolts.

2. Remove the doctor blade using slow,

steady pressure. Work carefully along

the length of the blade holder, pulling

short 6" to 9" sections until the blade is

totally removed.

3. Clean all ink from the hold-down cavi-

ty to ensure that the new blade will sit

in the assembly properly.

4. Install a new blade in the hold-down

cavity.

5. Tighten the hold-down bolts slightly,

working from the center out to each

end.

6. Tighten down the hold-down bolts all

the way, again working from the cen-

ter out to the ends to ensure the blade

is seated evenly.

In many cases, the blade assembly must be

broken down to allow for further cleaning

before the new blade is installed. This step

removes any pooled ink from inside the hold-

er. It is especially important if the next run

has a contrasting ink color that can be conta-

minated by the old ink color.

When cleaning up water-based inks, the

doctor-blade assembly should be thoroughly

dried. Moisture trapped within parts of the

assembly can result in rust damage. The

assembly should be set on end to dry rather

than face down to ensure that the moisture

can escape.

Cleanup Ink Pans

The next step after washing the doctor-

blade system is cleaning the ink pans. The

following procedure details a typical ink

pan cleanup:

1. Put the pan into position for washing.

Scrape any liquid ink into the drain

hole.

2. Place a rag at the bottom of the ink pan

and saturate it with cleaning solution.

3. Pass the rag over the entire interior of

PRESSROOM PRACTICES 205