Screen Printing Overview - Murakami Screen

Murakami Screen

The Perfect Screen
Complete exposure of the emulsion film assures durable stencils.
Clarity of lines and quality of print improve with proper exposure.

The Perfect Screen

Screen Tools
50x Microscope Thickness Gauge Moisture Meter
Tension Meter
High Quality Coater

Embellishment Techniques
Glitter
Foil
Dusting
High Density
Puff Inks
Discharge
Waterbase

Glitter Printing
Quality of mesh is crucial to
consistent glitter printing.
15T and 25T threads per inch
are most commonly used for
their large mesh opening.
Mesh openings need to be
larger than flake size to print
well, otherwise the mesh will
plug in.
Viscosity reducers and flow
additives help keep the flakes
from clogging the mesh.
Art should be designed so that
the smallest art element is 2x
the chip size.

Dusting is another method of glitter
printing.
A tray is filled with dry glitter flakes
near the unload station of a press.
All inks are flashed except the last
“glue” screen.
The glue screen usually is a clear
gel printed through a 60 mesh
screen with a 250 micron thick film.
The printed side of the shirt is laid
onto the glitter flake and gently
pressed into the glitter.
The gel picks up the glitter and
binds with it when it is cured.
Much more sparkle and reflection
than standard glitter printing.
Excess glitter flake can be
vacuumed off of shirt and returned
to tray.
Dusting

Foil printing can be
accomplished on press or off
press.
On press foiling is done prior to
the plastisol print. Glue is flash
dried enough so it is very tacky,
the foil can then be burnished
onto “hot” foil adhesive, usually a
gel printed through a 200 micron
thick stencil through a 60 mesh
screen.
Off press foiling will print the glue
last, the shirt cured in an oven
and the foil applied with a heat
transfer press. Waterbase and
discharge inks are commonly
used with this method.
Foil Printing

Recent ink improvements have
allowed plastisol to be used in
the same manner with a final
“resist” layer of ink printed over
plastisol to prevent the foil from
adhering to the print.
Textured foil affects can be
made by printing puff ink with a
coarse mezzotint pattern, flash
cured, and then printing a
continuous glue film over the
flashed puff print. The result
can simulate gold nuggets, or
highly reflective facets of the foil
print.
Foil Printing

Avoid solid areas. Keylines and
textured fills work better.
Consider using a base plate
underneath the glue plate to
elevate glue level above the shirt
surface.
Foil adhesives can be printed over
flashed textured puff ink or high
density for a raised look.
Apply foil when shirts are warm.
Re-warm shirts if foiling is difficult.
Use only foil designed for textile
imprinting. There are many types
of graphic hot stamping foils that
will not wash well.
Foiling Tips

Waterbase Printing
The stencil is the most important
part of waterbase printing.
Murakami Aquasol HV and TS
have unmatched durability.
Waterbase can print saturated
prints, ones with total ink
coverage and still be soft to the
hand.
Waterbase can overprint colors to
achieve secondary colors. Ex:
printing yellow over red will
produce orange. The orange can
be modified by adding base to
either the red or yellow to shift the
orange to the red side or yellow.
Softer 65 durometer squeegees
help saturate fabric with ink and
are easier on the stencil.

Discharge Printing
Discharge is water base ink for
dark shirts.
The shirt must 100% cotton and be
dyed with reactive dyes in order to
discharge. Not all shirt colors
discharge well, pre testing of shirts
is recommended.
The ink “bleaches” out the shirt
color and deposits colorized
waterbase component.
Like waterbase the print can have
100% coverage and still be soft to
the hand.
Raw uncolored Discharge can be
used as a base for a plastisol print.
This can yield a much softer hand
than using a plastisol base

Discharge Examples

Simulated Process Printing
Simulated process is actually spot
color separations with halftones.
Each color is separated into a
“discrete” layer.
In the guitar at left are basically
four colors. Rust, orange, gold,
and white. The black shirt can be
used for black.
These four colors can be spread
during the separation process to
overlap.
By adding 10-30% halftone base to
these colors they will blend better
where they overlap.
Slash (the guitar player pictured
here) could have a white, a mid
tone gray and a darker gray to
simulate the smooth tonal values

Simulated Process
The base also plays a crucial role
in final print quality.
For a softer hand consider using a
clear halftone base with opaque
inks.
To achieve two colors from one
screen design the print to print on
base and on shirt fabric. The ink
printed on shirt will be darker, while
the ink printed on a base much
brighter.
Consider using two bases to get
even more color from one screen.
While the guitar may have a white
base, Flash may print better with a
dark gray base. You can print two
bases then flash to achieve a
multicolor base.

Simulated Process
• Simulated process has significant
advantages in automatic production.
• Different color shirts will all have an
identical looking print since the ink
system is opaque. Opaque yellow gold
looks the same on black as it does on
red. A valuable production trick when a
customer orders many different colored
shirts.
• Simulated process screens generally
employ a specific halftone count and
angle with a tonal value of 5-95% dot.
That means any positive or negative
halftone less than 5% is either
eliminated or output at 5 %.
• Some magic numbers: A 55 line
halftone output at 7 degrees can print
through a 200 mesh screen. This allows
good ink deposit to maintain opacity.

Simulated Process
Flesh tones print much better with
simulated process.
Four color process does not handle flesh
tones well, Sim Process by contrast can
use inks that match the original exactly.
Sim process colors can re-create art
more accurately than 4/C process on
dark shirts.
Sim Process does use many more
screens to achieve a print.
Presses with up to 18 stations are
necessary to achieve a 12 color print due
to flash cure and cool down stations.

Sim Process Examples

Sim Process Examples

Four color Process
Four color process screen
printing is similar to magazine
printing.
Yellow, Magenta, Cyan, and
Black are used to create a
multitude of colors.
Best printing is obtained on
white shirts, and very light
neutral shirts.
4/C Process inks are very
transparent to allow the colored
dots to combine to make
secondary and tertiary colors.
4/C Process on blacks is very
difficult by hand and almost
impossible on an automatic
press. Quite often a discharge
base is used if printing on black.

4/C Process
On press tips: 4/C process inks
straight out of the can are often too
strong.
Mixing colors with 10-30% halftone
base will achieve smoother
blending of color.
Only matched screens with similar
tensions, mesh counts, and
squeegee durometer should be
used.
If a color shift in the image makes
it appear too red, add halftone
base in 10% increments until you
see the colors you wanted. The
same holds true if it is too blue or
too yellow, add clear halftone base
to the strong color screen.
To avoid moire select a starting
angle of 7.5 degrees for yellow and
standard rosette angles to 7.5.

4/C Process
When printing black ink use a black
specifically designed for process
printing. Regular black is too
strong and does not print halftones
well.
Some designs need very little
black, some designs do not need
the black plate at all.
To determine proper mesh mutiple
the halftone line count by 4.5 for
the correct mesh.
45 line halftone output at 7 degrees
x 4.5 = 202.5 so a 200 tpi (threads
per inch) will print with no moire.
65 line x 4.5 = 292.5 so a 300 tpi
screen will print without moire as
long as the starting halftone angle
is 7 degrees. There are many
angles that won’t moire, 7 degrees
for the first screen helps.

Index printing is very similar to sim
process printing. The difference is in the
dots.
Index printing uses a random stochaistic
dot that is uniform and much smaller in
size. Sim Process uses halftones that
have dots from 5% to 95%.
Separations are a snap from Photoshop.
Go to mode/index color, then select
custom color from the drop down menu.
A pallet will appear. These colors can be
modified to allow better secondary color
on screen. Anywhere two similar colors
border each other can be “spread” by
using the contrast tool, level tool, or
curves.
Index does generate odd color
combinations to achieve secondary
colors. It is sometimes necessary to
erase dots that are in the white or very
light areas. In the example shown I
would remover any blue or purple dots
appearing in the light beige basket or
ballons. They appear as confetti in the
final print and look like a pinhole.
Index Printing

Index Printing
• Index printing can achieve
more secondary and tertiary
colors than sim process. By
thinning colors with up to 30%
clear halftone base the inks will
mix together easily in printing
and produce smoother color
transition and improving subtle
color details.
• Like Sim Process, index
printing can print on any color
shirt since the base is generally
a white base plate.

Index Printing
Base plates for index printing need
to be “choked” so they don’t appear
as a halo in the print.
This can be accomplished by taking
the image shown, changing it to
grayscale mode, and inverting it.
You print a negative image base on
a colored shirt using black shirt or
black ink for the shadows, the base
is only under the brightest colors.
With the negative grayscale of the
image on the right adjusting the
levels, or brightness and contrast in
Photoshop will reduce the amount
of base printed.
Generally the base should only print
90% of the image with some of the
color plates printing onto the shirt.
The base, unlike the colors, works
better when output at 55 lines, 7.5
degrees so the thick white ink can
print through a 200 mesh screen.

Gel Printing
The webbing on the Spiderman’s
suit is commonly printed with a gel.
This image would be printed with
sim process technique with clear
stretch ink base beneath the gel
print for image flexibility.
The gel print would be printed last
through a 250-400 micron thick film
on a 60 mesh screen onto the
stretchy base.
Without a “high-density” thick film
screen the gel ink print would be
very thin.
The goal is to get a raised gel print
on all his webbing.
Glow in the dark additives in the gel
and white highlight screen could
also create some great effects to
boost sales.

Curing gel ink requires special
handling.
Oven speeds need to be
slowed down and temperatures
raised slightly so the gel turns
clear and “domes.”.
When a gel print comes out of
the oven it is extremely sticky.
(That’s why it is used for foiling
as well.)
Avoid letting the hot gel ink
touch other areas of the print, it
will fuse immediately with other
gel ink.
Gel Printing

High Density Printing
High density printing lends
itself to spot color graphics.
Both the red and white are
candidates for high density ink.
In most cases either the white
or red could be printed in high
density, the white being easier
to print than red due to the
large red print area.
Printing a clear or a choked
white base will help the high
density ink stay on the surface
and not get pushed into the
fabric.

High Density Printing
Thick Film from Murakami has
unique properties that make
printing high density easy.
Thick Film has better resolution
allowing for more detailed art.
When exposed and developed
the side walls of the stencil
have a very vertical wall with a
sharp stencil shoulder.
This allows ink to transfer with
minimal squeegee pressure.
Squeegee pressure needs to
be the absolute minimum
pressure to get the ink to
separate from the screen.

High Density Printing
For dramatic high density ink
thickness of 1/8” or more it is easier
to print stacked layers of high
density.
In this image it would be possible to
lay down a 200 –300 micron white
high density base, flash it, and print
another 200 red plate, flash it, and a
300 white plate for the letters.
Stacking requires analyzing the art
and combining elements to raise the
elevation equally.
It is impossible to print the white in a
400 micron screen, flash it, and then
print a 400 micron red.
When designing stacked high
density print all elements as a base,
possibly several times, then print
200 micron screens for the color.
Raise off contact for every new
elevation of high density printing.

High Density Examples

Newman Roller Frames
Retensionable – all screens
can have matching tensions
at optimum tension levels.
Capable of Pin Registration
Screens
Stretch and Glue Aluminum
Lose tension immediately, and
continue to lose tension in
production.
Only high quality mesh will
maintain good tension levels.

Screens
• Stretcher with several screens being
stretched on the bias to prevent
moire. Easier and less costly to
change angle of halftone during
output of films.
• Typical tension on a 300T would be
to perform a rapid stretch technique.
• The mesh is brought up to ever
increasing tension four times.
• First 15 newtons, Second 19
newtons, Third 22 newtons, Fourth
25-27 newtons, then allow to sit for
five minutes or longer.
• This will result in the highest
retained tension after being cut out,
about 22 newtons after cutting.
• After the initial print run tension will
drop to about 17-19 newtons. Only
a high quality mesh will retain that
tension. Cheap mesh will continue
to lose tension with every print run.

Newman Roller Frames
• Newman Roller Frames can be re-
tensioned for the life of the mesh.
• Murakami Smartmesh requires
minimal re-tensioning. After the
second or third re-tensioning roller
frames can maintain 22-25
newtons.
• Higher tension is a distinct
advantage when printing halftones,
high density, base plates, large
print areas, and overall print quality
and clarity.
• There are automatic stretching
tables that can bring tension up
very quickly minimizing labor costs.
• Newman roller frames also can be
fitted with a pin registration system
that can cut set up time by 80%.

Presses
In Line 5-color Graphic Press 12-Color Textile Press
5 Color Container/Bottle printer

Textile Presses
• Circular “carousel” presses are the
press of choice for most textile
printers.
• Most printers use four “heads” for
flashing the base with a cool down
station, and flash the print just
before the keyline print, or high
light white.
• This will effectively eliminate four
colors from a twelve color press.
• 12-18 color presses are common in
fashion imprinting.
• Athletic printers can use 6-8 color
presses since most designs are 2-3
colors. It is not uncommon for
athletic printers to use two flashes
as well resulting in only a few
colors being printed.

Textile Presses
• Commercial textile printers base
their production on the presses
hourly output.
• The fastest presses use servo
drives to move the pallets.
• Servo Press: 800-1000 pcs/hour
• Pneumatic Drive: 400-600/hour
• The numbers above represent
“index speed”.
• “Yield” per hour is often half due to
poor screen making, mesh falling
out of registration, pinholes.
• Quality Murakami emulsion and
mesh can achieve non-stop
production. This can often be the
difference in staying in business or
going out of business.

Graphic Presses
• Graphic In line presses are almost
exclusively printing UV ink today.
• UV ink can be cured in line with a
separate UV lamp positioned after
each print head.
• The print is completely dry after the
last print since it cures immediately
after passing below a UV light
source.
• Ink film thickness is a critical part of
graphic printing.
• Specific ink thicknesses are
needed in order to cure completely.
• Most large volume movie posters
and POP displays are printed by
screen rather than by digital due to
production cost advantages.
• Print speeds of 300-500 per hour
are typical.

Container Printing
• Container Printing is done on
high speed in line printers
using UV ink and in line UV
curing stations.
• Designed to run extremely fast,
production speeds of 1000-
1500pcs per hour are possible.
• Only the finest mesh and
emulsion will perform well on
these presses. Production
needs to run non stop.
• Ink film thickness needs to be
controlled as well to insure ink
cure.

Volume Fabric Production
While not common in the US, step
and repeat tables like this are still
in use throughout the world.
They are gradually being replaced
by “roll goods” printing that uses
cylindrical screens, or etched
copper cylinders for volume
production.
Step and repeat fabric is air dried
with one color at a time printed.
Engineered prints of sleeves, front,
and back of garments are one
common use.