Clarke Joe, Lynch Colleen C. M&R Professional Screen Printing Series

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PAGE

. 21

Cure or fusion is a time-temperature balance, which means

that you can make up for a shortage in one with an abundance

of the other. If the time is long enough, the temperature can

be lower. The 300° listed in table 3.14 is not nominal, but it is

a real world number that can typically be achieved with indus-

try equipment. Plastisol inks fuse from 200° to 2000° but the

former would require an impractically long dryer retention and

the latter would prove to be dangerous.

Flash curing is a preheating station for some of the garment

and some of the ink. If you flash cure, the part of the gar-

ment under the flash gets hotter. The ink printed on the shirt

prior to the flash becomes hotter when flashed and remains

hotter than those colors printed on top of the flashed inks.

They may be closer to room temperature. The flash can ensure

that the ink is totally cured, but relying upon it to do so, is

risky business. For example, the first time you stop and dont

put the shirt into the dryer immediately after flashing, it cools,

and its dryer exit temperature is lower than the balance of the

shirts. A consideration at the other extreme is the flash can

superheat the ink and lead to bleeding, sublimation and shrink-

age. For information on how to evaluate fusion refer to page

3.20 for details.

RReemm

eelltt

Remelt is the level beyond fusion or cure, when the resin

begins to soften and flow independent of the influence of the

plasticizer. It is this property that prevents ironing plastisols, as

well as makes heat transfers a viable product. The remelt point

of the ink should be the maximum possible for direct-print

plastisols, so this threshold is not crossed in production.

Should this happen the inks may become very thin, you risk

both dye bleeding from sublimation and migration,and hot

tack at this stage can weld the inks together at the end of the

dryer.

HHoott TTaacckk

Hot tack is known in our industry as after-flash tack. It is

determined by the combination and type of resin, plasticizer

and fillers. It is a form of temporary adhesion known as diffu-

There is no need to sustain the

fusion temperature once the ink

has reached it, but there are issues

that need to be recognized. The

garment will act as a heat-sink,

specifically in the case of fleece.

The fabric mass of a T-shirt is

often less than 25 percent but a

sweatshirt is often over 75 per-

centmore of it is fabric and less

is airspace. Before the entire ink

film can be brought to cure tem-

perature, the garment temperature

must be sufficiently high, so that

equilibrium is reached. In practice,

this means that the ink on a

sweatshirt will generally exit the

dryer at a lower temperature than

a T-shirt under the same condi-

tions. You will want to double-

check the sweats for cure, particu-

larly if they are run at T-shirt set-

tings.

High humidity has an affect on

the curing level of the ink; due to

the fact the garment holds mois-

ture. The moisture regain of cot-

ton is 35 percent and that mois-

ture must be dealt with before the

ink will cure. In high humidity

environments you may want to

double-check the cure of the ink.

Some synthetics will take more

energy than others. This is based

on the specific heat of the com-

position of the garment. The spe-

cific heat is an indicator of the

rate of increase in temperature.

For example, a nylon garment of

the same construction as a poly-

ester garment will take more time

or temperature to elevate it to a

given temperature point.

Inks

usion Tips

PAGE

. 22

sion bonding. To make ink that has very high hot tack, one would start with a

soft (co-polymer) resin and add an equal amount of high-solvating plasticizer

(over 50 percent). The hand would be very soft and the ink would level and pene-

trate as soon as it was heated.

Inks similar to this, used on highly elastic materials such as SpandexÒ, would

have a rating of five on the hot-tack index. Most pigments and fillers are inert

and are unaffected by the gelation or cure of the ink. As pigments and fillers will

appear on the surface of the ink, they act to reduce the hot tack, but are not as

influential on the hot tack as the plasticizer/resin ratio. Note that a smoother sur-

face is more prone to after flash tack, but produces higher quality prints.

PPhhyyssiiccaall

There are dimensions of plastisol inks that do not fall into optical, rheological or

thermal. These are categorized as physical properties and include; the size of the

particles of ink, its reaction to infrared energy, its ability to wet a surface and to

be wet once it is gelled. Included is the percentage of plasticizer because lower is

better and the hardness of the cured ink film. All of these play a critical role in

the aesthetics and performance of the ink and are listed below.

GGrriinndd

The grind of plastisol ink is a measurement of how fine the agglomerates (collec-

tions of particles) have been reduced in size. Although the test method does not

gauge viscosity, the relative viscosity of the ink nonetheless, influences the test.

The standard grind gauge runs from zero to eight with eight being the finest

grind. This fineness index can be converted to a nominal agglomerate size. Each

whole number is approximately equal to a 12m increase in diameter. For example,

a grind of four equals a 51m diameter, while a five equals a 38m diameter. If this

Chapter 3

Room Temperature 72

°°

è Ink remains as it appeared in the container.

Greater than 72

°°

è Ink drops in viscosity as on a Turnabout mixer.

110

°°

è Ink reaches its low viscosity point.

125

°°

è Plasticizer becomes aggressive, fluxes resin surface.

150

°°

è Resin gels, plastisol becomes dry and immobile.

175

°°

è Fluxing continues at a slower rate.

250

°°

è Dye sublimation begins.

Total Ink Film Reaches 300

°°

è Fluxing complete, optimal ink properties achieved.

350

°°

è Resin softens and ink re-melts.

Figure 3.16 The details listed in the table above are generic; they do not necessarily describe a particular ink brand or

series. These properties are offered as a "thermal timeline" of events as the plastisol is exposed to heat.

PAGE

. 23

dont seem like much of a disparity, consider that the 38m par-

ticle has a surface area of 4536m² and the 51m particle has a

surface area of 8171m²-and these are only one number apart on

the grind gauge.

Grind is a reasonable predictor how easily the ink particles will

transfer through the mesh. Of course the particle shape,

weight, size and pigment loading are significant factors that

affect ink transfer, but a coarse grind will make matters worse.

If the grind is poor, the plasticizer continues to migrate into

the agglomeratesthe ink gets very tacky and thick. Once this

happens nothing known to man will reverse the process. Poor

grind is the primary cause of thick, tacky inks; build-up; mot-

tling and after-flash tack.

EEmm

iissssiivviittyy

Emissivity is ratios of an objects tendency to reflect versus

absorb energy. This is a real-world factor if you are using a

non-contact, infrared pyrometer. These heat guns should

ideally be calibrated to the emissivity of the surface they are

about to measure. Emissivity is affected by the texture, gloss

and color of the product, as well as its chemical make-up.

Emissivity also changes over a range of temperatures.

For example, black ink, at gel, will have an emissivity ratio

around 0.70, while whites, at fusion temperatures, are around

0.95. Most of the default settings are 0.95 and there is no

problem unless you are looking for absolute readings

SSppGG ((ssppeecciiffiicc ggrraavviittyy))

Specific gravity of ink is the ratio of ink weight to an equiva-

lent volume of control water. This data allows the manufactur-

er to easily determine the weight of any volume container.

Because white pigment (TiO²) is small and spherical, it packs

well so the density and specific gravity of whites are very high,

making white pigment heavy. A 1.49 ratio would mean that the

ink weighs nearly one-and-a-half times the same volume of

water. It is advantageous to have white ink with a high weight

to ensure two things: there are no air pockets and there is a

relatively high volume of pigment in the ink.

A pharmacist uses a mortar and

pestal to breakup clumps of dry,

powder particles and make a more

homogenous prescription. The ink

manufacturer has to achieve this

grind twice with your plastisol ink

before it is finished. There are

grind parameters for the pigment

dispersion stage, and also for the

finished ink. Though the two

approaches differ radically, the

goal for each is the samereduce

the size of the clumped particles.

A generic description of pigment

dispersions follows.

The pigment and plasticizer are

premixed into a slurry or paste on

a high-speed dissolver mixer.

Surfactants and fillers are added at

this time. This "premix" is not

finely ground and must be put

over a milling machine. There are

sand mills; ball mills, colloid mills

and three roll mills to name a few.

The choice of mill is based on the

needs of the pigment and its abra-

siveness. Whites for example are

so hard they will nearly destroy a

three-roll mill and the shear thick-

ening nature of the dispersion

makes it unsuited for some mills.

The premix is taken to the mill

and under specific time, pressure,

velocity and clearance the clumps

of the pigments are broken down.

What is left is a smooth paste that

requires less addition of disper-

sion to develop color. This effi-

ciency has several advantages;

lower raw material cost ink, series

with print properties that are

more similar and colors that are

cleaner, brighter and more intense.

Inks

Ink Grind

PAGE

. 24

SSuurrffaaccee TTeennssiioonn

The surface tension of the ink is its ability to wet-out a sur-

face. At times this has little relevance-but at other times it is

critically important. When the plastisol is printed directly onto

the garment, wetting is a non-issue. The adhesion is mechani-

cal and the substrate is absorbent so the ink cant creep across

the surface. But when the ink is printed on an underbase or

over another color, all rules change. The compatibility of the two

inks is gauged by the surface tension (liquid) of the liquid ink

and the critical surface tension (solid) of the flashed underbase

ink.

Lower-surface-tension inks wet our more surfaces better and

faster than inks with higher surface tensions. In fact, if the liq-

uid has a higher surface tension than the gelled or fused ink,

the two are incompatible, image stability and adhesion can be

at risk. And if youre printing a process job, color balance just

flew out the window.

The surface tension of the ink is dictated initially by the sur-

face tension of the plasticizer, but this can be altered with

additives. The lower the number the better. Typical however,

additives used to reduce surface tension tend to reduce critical

surface tension as well. The ink maker must be wise in his

choice or the result will be ink that wets-out a gelled surface

better, but is more difficult to wet once it is gelled (see sidebar

on page 3.32 for more information on surface tension).

CCSSTT ((ccrriittiiccaall ssuurrffaaccee tteennssiioonn))

Critical surfacetTension is a measurement of the tendency of

the gelled or fused ink surface to be wet-out. The best exam-

ple is the slick surface of TeflonÒ that nothing sticks to.

Teflon® has a very low surface energy, around 13 dynes per

centimeter, and most liquids like eggs have a surface tension

higher than 13, so they cant wet the surface. When they evap-

orate they stick to them selves, but not to the skillet, so they

fall right off.

Youve probably seen the results of incompatible surface ten-

sions, when the ink does not want to stick to the underbase.

There is a balance that can be disturbed if the underbase is

There are two major components

in plastisol ink; resin and plasticiz-

er. The resin is a powdered, dis-

persion-grade polyvinyl chloride

and the plasticizers are liquids,

specifically high boiling esters.

When the two are combined they

react in a particular manner, which

is described below:

1. The resin and plastisizer are

blended.

2. The plasticizer solvates the sur-

face of the resin.

3. The plasticizer is now diluted

with solvated resin.

4. The diluted plasticizer cannot

continue to solvate.

5. Equilibrium is reached and

maintained if:

a. the plastisol is not exposed

to heat.

b. the fillers do not continue

absorb plasticizer.

c. there are no resin cavities

for the plasticizer to

migrate into.

6. If equilibrium is not achieved,

tack increases due to aging.

Chapter 3

Constructing

Plastisol

PAGE

. 25

taken over its gel point and too close to cure. As the ink is

heated the critical surface tension decreases to a point beyond

fusion. Eventually, it will begin to increase with sustained or

incremental temperatures. The range of critical surface tension

in white plastisols is from 30 to 44. The higher number allows

overprint inks to trap (stick) easily and the lower number is

very resistant and difficult to print on. (Refer to page ___ for

details on surface tension).

PPeerrcceenntt PPllaassttiicciizzeerr

This is one of the most critical aspects of the plastisol ink,

and its excess is triggered by a poor grind. Far too often the

manufacturer does a poor job of blending the ingredients in

the ink, and knowing before hand that the ink will age-up in

viscosity, he adds plasticizer to retard the aging and reduce the

final viscosity. The ink ages (or thickens), then it meets the

standards set with viscometers, but viscometers dont inform

us how the ink will perform on press.

The lowest practical percentage of plastisizer is 35 percent and

the goal of the manufacturer. More plasticizer creates a multi-

tude of problems. It retards the gel rate, creates after-flash

tack, reduces the critical surface tension, increases the chance

of dye migration, sacrifices opacity, promotes build-up, raises

the fusion temperature and makes ink that is low viscosity, but

high tack. Like warm honey-and it still wont print well.

SShhoorree AA

The hardness of the ink is an indicator of the drape and flexi-

bility of the printed material. It is established on a Shore-A

scale for elastomers, and a higher number indicates a harder

product; less likely to drape. This property is dictated in part

by the type and percentage of resin in the ink. More resin

makes for a harder product, while some types of resins are

harder than others. Hardness is indirectly proportional to the

quantity of plasticizer in the system. More plasticizer means

softer ink.

The hardness is checked against a totally fused thick-film (at

least 1/8 inch thick) deposit. Employ the same meter used to

check the durometer of squeegee blades. It operates similarly

These vary from manufacturer to

manufacturer and there is little

consistency. The only common

denominator is they dont contain

pigment. There are three terms

that give you an indicator of the

performance of the transparent

ink; unfinished ink, finished ink

and ink modifier.

There are unfinished inks that are

intentionally short of their plasti-

cizer balance and are to be used in

conjunction with pigment disper-

sions for color matching conven-

ience. Be cautious, as these are

very often unstable and age-

upfaster due to the reduced

amount of plasticizer. Once ink

has aged, there is no turning back.

There are finished inks that will

not accommodate color concen-

trates, but can be used to over-

print an image for durability or

gloss control. Some finished inks

are intended to mat-down gar-

ment fibers and serve well as

transparent underbases. Another

course of action is to add these,

in virtually any amounts, to an

existing color to increase its trans-

parency. Of course the properties

of the color are compromised by

the properties of the additive.

Finally the ink modifiers, which

are marketed under a variety of

names, but usually intended to

solve a specific problem. These

include hand modifiers, which at

the cost of opacity, improve pene-

tration and increase drape. Some

of these are highly plasticized

(refer to page 3.25 for details), so

be cautious. There are also modi-

fiers that are recommended for

process-color printing to control

the balance of the four colors.

Inks

Base vs. Clear

PAGE

. 26

to a tension meter, except it has a pin on the bottom of the

meter, rather than a foot. Hold the meter with the pin facing

the printed sample; firmly press the pin into the fused ink. The

meter will register the hardness. This number should be evalu-

ated along with the fused deposit thickness you normally print

for drape and hand acceptability. For example, the first ink has

a hardness of 50, but must be printed at a five-mil deposit to

be opaque. A second type of ink, of the same hardness, prints

at three-mils and matches the opacity of the first ink -the thin-

ner deposit will have a better hand.

If you are having problems with

flash times and after-flash tack,

you have an ink problem and

should find ink that is suited for

flash-curing applications.

Meanwhile the fix is to add

blending resin, which is known to

our industry as flash additive.

As is the case before you add any-

thing to the plastisol, it should be

stirred thoroughly-not a quick

spin with a spatula. It is wise to

use a Turnabout Mixer allowing

the low-shear to gently reduce the

viscosity of the ink in a minute of

stirring, without generating excess

heat, typical of high speed mixers.

Volume mixing (quart, gallon, etc.

measurements) is a very risky

business, so we recommend that

the resin be added by weight. Use

a scale that measures to a tenth-

of-a-gram for quarts, to one-gram

for gallons and to five-grams for

five-gallon pails. High viscosity

and subsequently high tack will be

your limiting factors, but begin at

a quarter-percent of resin, by

weight, to the ink. Add it slowly,

as the Turnabout continues at

slow speed.

The additive will partially combine

with the plasticizer in the ink, so if

you must add, do so in advance of

the press run. After all if you have

had problems before, you can

expect to have them again. So mix

the additive a minimum of 24

hours, but ideally 72 hours, before

the press run. This allows the ink

to reach equilibrium and you will

find fewer additives will do the

job.

If you over shoot the mix, the

best advice is to dispose of it

Chapter 3

Flash A

dditiv

Figure 3.18 This HiRes AccuColor© print has an extremely soft hand due to the inks

used for the underbase and the fact that they were printed at less than one mil deposit. Red Hot

Mama, image rights liscensed by Blue Chicago and T-shirt printed by Target Graphics Ltd.

PAGE

. 27

Troubleshooting Ink

If you have read the preceding pages on the nature of the

plastisol inks, it will help you identify ink problems, and other

related issues, when a problem occurs. This section demon-

strates how to put your newly gained knowledge to work by

dividing ink troubleshooting into four categories. These cate-

gories are the most common issues associated with plastisol

performance; ink tack, build-up, ink adhesion and surface

energy, test for fusion, test for temperature, ink mileage.

TTaacckk

Screen printing is unusual when it comes to ink tack. Most

other ink transfer processes need, and even flaunt, the tackiness

of the ink. But we have a hydraulic pumping system that trans-

fers ink; high tack level is a problem. It is more difficult to

transfer higher tack level ink- such ink requires a higher shear

rate.

Shear (rate) is the force applied to the ink on the surface of

the screen-it is intended to cause the ink to become thinner. At

this state of lower viscosity, the ink should be easy to pump

through the mesh openings. Shear (rate) increases in direct

proportion to the following:

1. Higher off-contact or peel.

2. Higher mesh tension.

3. Lower squeegee angle.

4. Higher squeegee speed.

The higher the shear rate, the thinner the ink becomes over a

relevant range. Plastisols and virtually all printing inks need to

be shear thinning. That is, as a shearing force is applied (like

the squeegee or the Turnabout Mixer) the ink drops in

viscosity.

To cause this shear-thinning drop, with high tack ink, requires

excessively high shear rate and a mesh with an excessively high

flow rate. In the vernacular we say, Use the coarsest mesh you

properly. Do not try to reduce the

ink and run it on press. Its per-

formance will be the worst possi-

ble and downtime is the enemy of

profits-dont risk it.

Adding this flash additive resin

will alter all of the properties of

the ink on press and on the print-

ed image. On press the grind

(Refer to sidebar page 23) will not

be as high and the mesh can act as

a strainer by filtering out particle

clumps. Be particularly cautious if

you are on a mesh with a small

opening, either higher count or

thicker threads. If this is a prob-

lem you will find that it gets worse

as the run continues. Temporarily

you may need to run a lower blade

angle and a higher squeegee

speed.

Flash additive may worsen build-

up as it raises the tack level of the

ink. Your response to this will

necessarily be more force and if

so you may see perimeter build

up. If the ink tends to build up in

the central areas, the addition of

flash additive will not adversely

affect this and may slow it down.

But our best advice here is to get

ink that works, don't get caught

up in ink repair.

Flash additive will reduce the gloss

level of the ink and stiffen the

hand or drape of the printed film.

It is not a solution for dye bleed-

ing but will not encourage bleed-

ing. All things considered, flash

additive is a temporary fix so that

you can stay in production by

compensating for ink deficiencies.

Asking more from the product is

unwise.

Inks

Flash A

dditiv

(continued)

PAGE

. 28

can find and crank down on the squeegee, hardly good advice

for quality printing. However, high-tack inks are prevalent in

our industry (refer to the how-to on page 3.30 for details).

TTaacckk vveerrssuuss VViissccoossiittyy

Do not confuse tack with viscosity. The best analogy is Cool

Whip desert topping and honey. Cool Whip is high viscosity

and low tack. Honey is low viscosity and high tack. The best

printing inks are more like Cool Whip and less like honey.

With honey, no amount of shear will successfully transfer it

through the screen and such excessive shear will cause a lot of

problems on its own:

1. Premature stencil breakdown.

2. Premature tension loss.

3. Premature mesh ripping.

4. Oversized image distortion.

5. Perimeter ink build-up.

6. Smearing and blurring.

It is always best to cure the illness and not only the symptoms.

There is by far, more white ink

used by the textile printer than

any other color of plastisol screen

ink. It is very unfortunate for

screen printing, which is a pump-

ing process, that white ink is

absolutely the most difficult color

ink to pump.

And at times the ink seems more

difficult than others, for example,

in the middle of a press run.

Unless you are new at the game,

you have seen where all is well,

and all of the sudden the white

starts hanging up in the screen.

Well its occurrence was probably

not sudden at all, only its appear-

ance was sudden. It was probably

the long-term result of one of the

following factors.

1. Screen tension loss from

fatigue.

2. Gelation in the screen from

heat.

3. Dilatency (shear thickening).

Number one occurs frequently. If

you need to retention after every

press run, it may well be your

problem. Review the sections in

this book on press calibration,

off-contact set tings and squeegee

pressures. The warning signs will

be registration problems, smearing

and image stretch. If you stop the

press, wait and then start it again,

the condition will be the same.

Number two is unavoidable if,

and when, your heat gets out of

control. Review sections on flash

curing and plastisols. The warning

signs will be; as the ink warms-up

the deposit changes, and you per-

Chapter 3

Whit

e Hang-up

Figure 3.19 The

Turnabout is available in

three configurations for every

budget and viscosity of ink.

Each Turnabout comes with

a single and five-gallon blade

that are very easy to clean.

The DC version allows you to

mix slowly, so there is no heat

generation. Once the ink

begins to flow, you can speed it

up for a quick and thorough

mix. All Turnabout mixers

clean the bottom and sides of

the pail automatically. They

are ideal for mixing colors or

for stirring thick white ink, so

that it flows properly on the

very first shirt.

PAGE

. 29

If the tack in the ink you are currently using is too high, talk

to your supplier. Some printers will resort to modifiers to

reduce the appearance of tack-but there is no way to eliminat-

ing tack in plastisol, which means a compromise in the per-

formance of the modified ink is inevitable.

CCaauussee ooff IInnkk TTaacckk

The primary cause of ink tack is in the manufacturing stages,

in the selection of raw materials and their assembly. No one

builds ink that is difficult to printit becomes that way in time

and aging is an indication of poor manufacturing. The test

for tack is varied and unfortunately not often used by the ink

manufacturers. One test that is universally used and a general

gauge of high tack is the grind of the ink. The grind of the

ink is a measure of how well all of the particle agglomerates

are reduced in size and distributed in the liquid vehicle (plasti-

cizer) of the ink.

A poor grind would leave the resin agglomerates (particle col-

lections) too large and over time (72 hours plus) the plasticizer

would migrate into these clumps of resin and change every-

thing. When the ink was first made, it may have been creamy

because the plasticizer acts as an ink system lubricant  allow-

ing the particles and clumps to pass by each other, with mini-

mal friction. If this (plasticizer) lubricant is absorbed into the

clumps, and the ink is put under a shear, the friction will be

very high  we call it excessive ink tack.

Conversely if ink is finely ground, the amount of plasticizer

needed is minimal and the ink achieves a system equilibrium 

it doesnt get thicker or thinner. Initially when the resin is

mixed with the plasticizer, the surface of the resin is attacked

and becomes a part of the plasticizer. Now the plasticizer has

changed  it is thicker and less aggressive to the resin. The

goal is for it to reach equilibrium- so at room, shipping, and

storage temperatures, the plasticizer stays where you put it. If

the goal is achieved, there is no aging after the initial wetting

period of 72 hours. Such an ink mixture will require less plasti-

cizer-that is good news, because excess plasticizer will ruin the

ink (refer to page 3.25 for details).

ceive a lower gloss level. If you

stop the press for a while, and

start again, this one goes away.

Number three is subtle and may

be missed if you are not obser-

vant-there are no warning signs.

Dilatent fluids resist flow and

whites are very dilatent. The

percentage of pigment is high

between 17 and 27 percent is typi-

cal. Further it is very small, spher-

ical in shape, and very heavy. Just

like a set of billiard balls on the

pool table, white pigments tend to

settle, collect and push up against

each other. White ink acts the

same way, but in three dimen-

sions, and when the ink gets

warm, the particles can begin to

settle. Run the squeegee blade at

the highest angle possible and use

a moderate speed. Keep your

operating temperatures in control;

use a thinner mesh with a larger

opening, and a faster flood stroke.

If you stop and start again this

symptom will disappear.

Inks

Whit

e Hang-Up

(continued)

PAGE

. 30

Poorly dispersed resin results

in clumps of resin agglomer-

ates in the ink and there is no

way to improve the disper-

sion. Mixing would cause

excessive heat and gel the ink,

long before it would reduce

the sizes of the agglomerates.

Plasticizers (that do not

encourage tack) or surfactants

(wetting agents) can act as

lubricants and may improve

some performance properties,

but they do not solve the

problem of a poor grind and

resin agglomerates that are

welded together. That is the

exclusive responsibility of the

ink manufacturer.

BBeeffoorree MM

ooddiiffyyiinngg HHiigghh TTaacckk IInnkk

f you are to about to modify your ink, first you want to review the list below, to

see if in fact the problem is the ink. Ink hanging up in the screen can be the

press operators first inclination that the ink is not performing to specification.

The list includes a variety of symptoms that may occur when the ink fails to

transfer cleanly.

1. Is the ink fast fusing (refer to page 3.20)?

2. Does the screen mesh have an adequate flow rate (refer to

page 1.14)?

3. Is the screen tension adequate (refer to page 4.8)?

4. Is the off-contact distance high enough (refer to page 4.5)?

5. Is the ink tack exhibited all over the screen (refer to the how-to

on this page and review the information on page 3.29)?

6. Is the top of the screen clear (refer to pages 3.32 through 3.36

for further information)?

Chapter 3

Follow these steps to avoid tacky-ink problems:

1. Add the proper amount of the surfactant, as suggest-

ed by the manufacturer.

2. Use End Caps to compact the ink.

3. Calibrate the press.

4. Calibrate the flashes.

5. Sharpen the squeegee blade.

6. Use a thin mesh with a large open area.

7. Optimize the off-contact distance.

8. Lower the squeegee angle.

Dealing With Tacky Ink

How To

Instructions

Clarke Joe, Lynch Colleen C. M&amp;R Professional Screen Printing Series

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Clarke Joe, Lynch Colleen C. M&R Professional Screen Printing Series