General Guidelines for Screen Printing On Flat Glass
Typical applications cover appliance, automotive and architectural glass
Key
Elements
ARTWORK
Variables
Film Positive
ALTERNATIVE
IMAGING
TECHNIQUES
Computerization
SCREEN
Frame
Characteristics
Guidelines
Comments
Quality
Film must be clean, void of marks, greasy
stains, scratches or other blemishes such
as ‘static spots’
Poor artwork is the single largest cause of
poor print quality
Image
Image output must be solid of the correct
density,
complete
image(s)
intact,
geometrically accurate in representation
with no appearance of distortion, moiré or
banding
Printing can never better the original—only
equal it at best
Edge
Resolution
If necessary, re-output the film at a higher
DPI if edge quality of image is not smooth
or there is evidence of moiré/banding (see
above)
Check with imagesetter supplier for further
resolution and density recommendations
Accuracy
If printing more than one color, check
registration accuracy between the set of
films
Films shrink due to environment changes
which can cause registration problems later
CTS and Direct
Projection
A variety of Computer-To-Screen and
Direct Projection systems offer alternative
imaging techniques that do not require film
positives and perhaps other processing
steps employed in conventional screen
making. Follow system’s guidelines closely
for optimal error-free results.
Check image for unacceptable serrated
edges, as well as moiré with monotone or
process work and banding with vignettes
(dot gradations).
Type
‘Stretch & Glue’ and ‘Self-tensioning’ are
the two main types of frame systems
commonly used for glass printing
Stretch and glue frames are lighter, more
cost
effective
and
practical
for
auto/architectural glass
Self-tensioning frames are a more practical
consideration for appliance/white goods
due
to
close-tolerance
multicolor
registration requirements
Key
Elements
SCREEN
(Continued)
Variables
Characteristics
Frame
(Continued)
Size
Guidelines
Comments
Image size should ideally not exceed 65%
of the inside of the frame for architectural
glass
Percentage recommendations may not be
possible in all situations
50% for automotive glass
40% for appliance and other smaller format
sizes
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Allow as much space as possible from
squeegee to inside frame for good ink well
(see separate entry)
Consider equipment and other possible
limitations
Ink Well
Ensure there is a healthy space large
enough for the squeegee and floodbar to
clear the image at either end to prevent ink
from seeping back into the open image
area
Ink seepage due to insufficient clearance
will cause potential rejects particularly with
etched or frosted coatings
Tubing
Tubing/section size should be based on
overall frame size and desired tension
levels
Consult with fabric and screen supplier for
optimum recommendations
Construction
For extra large screens for architectural
applications, consider having corner
gussets and prebowed
Flatness
All four corners should lay flat on the print
table without any signs of warpage
Do not use if the frame doesn’t clamp down
flat as the image may distort as well as
other problems
Squareness
Corners squared 90º
An out of square frame can potentially lead
to registration and distortion problems
2
Gussets reduce corner
prevents cracking
warpage
and
Prebow reduces inward deflection under
high tensions and helps maintain tension
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Key
Elements
SCREEN
(Continued)
Variables
Characteristics
Frame
(Continued)
Standardization
Fabric / Mesh
Type
Guidelines
Comments
Keep frame sizes to a minimum to reduce
adjustments and set up times, particularly
with architectural applications
Determine one frame size (maximum) for
appliance and automotive jobs and no
more than three for architectural (S, M and
L for example)
Consider a universal master frame holder
to accept various frame sizes for
architectural applications
A master frame holder can significantly
reduce setup/changeover times (having
two sets: one on press and the other
prepared offline for next job)
Monofilament polyester
Low elongation polyester is the most
common mesh type used for glass printing
Stainless steel
Nylon
Stainless steel is good for conductivity
purposes
Typical mesh counts used for glass printing
with inorganic enamels are:
- Appliances: 86 – 380 Threads Per Inch
(TPI)/34 – 150 Threads Per Centimeter
(TPC)
Effects ink consumption, ink deposit,
opacity, screen tension, screen life among
other factors
Mesh Count
Consider particle size when selecting,
particularly for fine line images and
characters (see Aperture on next page)
Higher mesh counts (TPI/TPC) provides
better image detail to be reproduced
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3
- Automotive: 140 – 305 TPI/55 – 120 TPC
- Architectural: 74 – 255 TPI/29 – 100 TPC
Printing mediums other than ceramic frit,
such as other types of inorganic, organic,
elastomeric, solvent-/water-based or UV
(ultra-violet) may require different mesh
counts, processing and handling—refer
specifically
to
supplier’s
mesh
recommendations
and
processing
procedures as well as those of the ink
coating manufacturer
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Key
Elements
SCREEN
(Continued)
Variables
Fabric / Mesh
(Continued)
Characteristics
Guidelines
Effects how ink flows to edge of stencil
Thread
Diameter
Best to use thinnest thread possible for
small dots, fine lines and graduations
Thinner thread results in less resistance to
print
Aperture
POA
(Percentage Open
Area)
Mesh Color
(dyed)
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Aperture or physical opening size should
ideally be at least 3 – 4 times greater in
size than the largest particles contained in
the ink
POA is a useful guide to determine how
receptive ink will transfer to the glass
surface in comparison to other fabric
grades
Comments
Thicker thread is prevalent for glass
printing due to the aggressiveness of the
ceramic frit
Thinner threads typically deposit more
enamel and provide better resolution and
overall print detail
Aperture can be increased or decreased in
size by selecting a thinner or thicker thread
diameter
POA is determined by thread count and
diameter
Higher POA requires less squeegee
pressure and wear while permitting higher
printing speed
As opposed to white, dyed mesh impacts
quality and edge sharpness of the stencil
image
White mesh is cost effective for nondemanding applications such as flood/open
screens
Yellow or orange mesh provides better
resolution and definition than white
Dyed fabrics are best to use for all
photographically
reproduced
images
regardless of pattern
4
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Key
Elements
SCREEN
(Continued)
Variables
Characteristics
Fabric / Mesh
(Continued)
Tension
Guidelines
Comments
Screens should have enough tension to
allow for a clean separation from the glass
surface immediately behind the squeegee
during the print stroke with minimum offcontact
While each fabric grade has its own
desirable tension level, how straightforward
or demanding the job is needs to be taken
into consideration too
Follow fabric supplier’s recommended
tension level for each fabric grade, usually
around level I for automotive and
architectural and level II for white
goods/small format intricate jobs
Smaller screens withstand higher tension
levels than their larger cousins
Tension should be uniform within the
image area, checked in five places (center
and four corners) in both directions with
small screens, and consider up to nine
places for very large architectural screens
Follow stretching equipment’s procedures
for rapid tension
Stretching
Fabric stretched at a bias angle for glass
printing is generally not required so fabric
ought to be glued linearly better than 1%
angle to the screen frame
Fabric should ideally be held pneumatically
at the desired tension level consistently for
30 minutes prior to gluing
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5
Higher tension screens will
productivity, quality and yield
increase
If screen making is outsourced, establish
minimum ‘shipping’ tension for each fabric
type based on recommendations, as
opposed to when it is received, sometimes
referred to as ‘shipping’ or ‘transit loss’
Consistent print results and superior
coating uniformity can only come about
with close tension consistency regardless
of tension level or screen size
If stretching is outsourced, discuss
methodology to gain best results for
assured quality and consistency
Methodology behind the 30-minute rule is
to prevent screens from weakening too
quickly from repeated use, thereby
extending their durability and useful life
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Key
Elements
SCREEN
(Continued)
Variables
Characteristics
Fabric / Mesh
(Continued)
Preparation
Comments
All newly stretched fabric needs to be
degreased so that it’s surface is clean and
slightly abraded to promote better adhesion
of the stencil
Procedure and treatment techniques
involved are according to film or emulsion
used
Cleaned screen should ideally be dried in
an enclosed area or cabinet void of
collecting dust particles and must be
completely
dried/moisture-free
before
being coated
If stretching screens for storage purposes,
clean and degrease screens within 24
hours of coating and exposing
Test
Screens
Screens made for samples and testing
purposes should have the exact same
fabric grade and tension level that is used
in actual production regardless of what
they may be
Production can better match printed
samples, deposit thickness, color and
opacity/translucency when both screens
are made to the same specifications except
for size
Rest Period
When stretching has been completed,
allow at least 24 hours - 48 hours before
coating for reorientation of the fibers (this is
when the long side of large screens are
forced to bow in the center)
Rest period will help to prevent lines or
dots at the outer edge of the image
developing a curve, if the frame bows
along its length, as well as improving closetolerance registration
Type
While there are numerous types available,
they basically comprise of two groups
according to enamel’s chemistry: solventresistant or water-resistant
Select emulsion type based on type of ink
system to be used, being mindful that the
screen may not be used with all types of
printing ink
Emulsion or
Stencil Film
Application
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Guidelines
For capillary film
manufacturer’s
recommendations
application, follow
processing
For emulsion coating, one or more coating
strokes are required to encapsulate the
mesh
6
Full encapsulation is necessary to provide
integrity for maximum durability
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Key
Elements
SCREEN
(Continued)
Variables
Characteristics
Emulsion or
Stencil Film
(Continued)
Thickness
Guidelines
Comments
EOM (emulsion over mesh) on the
substrate side should be kept below 10
microns with coating recipes preprogrammed if using an automatic coating
machine
For superior quality image detail, EOM
should ideally be between 4 – 8 microns
depending on emulsion type
Following supplier’s recommendation to
attain mesh encapsulation, which may
require several test screens to achieve the
objective
Substrate side of screen should provide a
good gasket for ink transfer and image
integrity
Surface Roughness
Drying
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If there are any doubts about obtaining the
most desirable Rz value (measure of
roughness) with fine images, have test
screens made to determine optimal value
Screens coated with emulsion or capillary
film applied should be dried horizontally
with squeegee side uppermost in a clean
dust-free environment
7
Thinner EOM is recommended for fine dots
and lines as it reduces the unsightly ‘thickedge’ appearance
Thickness has no effect on ink deposit in
open areas except at the outer edges
Screens with a Rz value of 8 – 12 is
recommended for glass surfaces
If stencil is too smooth (lower than 8 R z),
static may damage the printed image as
the screen separates
If Rz value is too high, edge resolution will
be lost
Allowing screens to dry in a vertical
position will render coating or stencil to be
uneven and will lead to print quality issues
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Key
Elements
SCREEN
(Continued)
Variables
Characteristics
Guidelines
Determine correct distance of light source
according to screen/image size
Emulsion or
Stencil Film
(Continued)
Exposure
Determine correct exposure time, via a
light integrator, with the aid of an exposure
calculator
Suppliers will recommend optimum lamp
system according to screen/image size but
higher Kw lamps provides superior image
reproduction
Each fabric grade and emulsion thickness
will have its own unique exposure time that
should be programmed into the procedures
for consistency
Obtain a full vacuum seal between blanket
and exposure glass as it is critical to
prevent image distortion and loss of detail
For very fine line resolution requirements,
consider
the
‘secondary-exposing’
technique to improve definition and coating
integrity—more prevalent for appliance
applications
Keep exposure glass, top and bottom,
continuously clean of particle matter, tape
and greasy finger marks
GANA DD – DOC – 0111
Comments
Change lamps at the recommended life,
usually 1000 hours regardless of a light
integrator employed
Keep a record of each screen made,
emulsion applied, image (job #) and
exposure time for tracking potential
problems
Washout
Establish
acceptable
procedures
to
washout the emulsion, including spray
consistency and warm water temperature
95º - 113º F (35º - 45º C), if used and
highly recommended
Do not overly washout as it will irreparably
damage the emulsion/stencil properties
Blockout
and Tape
Blockout areas outside the emulsion/stencil
and tape according to set procedures
It is better for screen makers to finish the
screen completely and have ready for
printing than to allow printers to do this part
of the job
8
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Key
Elements
SCREEN
(Continued)
Variables
Characteristics
Guidelines
If outsourced, check maker’s QC
inspection sheet upon receiving screens
and keep on file
Emulsion or
Stencil Film
(Continued)
Final QC
Custom Taping
Prior to placing into production, inspect the
whole screen to ensure stated tension is
correct, the complete image is in tact (such
as half a dot missing), line integrity, edge
resolution acceptable (with the aid of a
loupe) and no appearance of banding,
moiré, etc
Mark up screen prior to production,
indicating where the tape will go when
processing various custom sizes with the
same screen/image
For professional-looking clean screens,
use a backlite washbooth designed for this
purpose including a high-pressure washer
with suitable PSI
Cleaning
Washbooth
Remove tape, adhesive residuals and any
particles of ink, including those at inner
edges of the frame
Comments
If necessary, keep a log of screens
recording tension of fabric each time it has
been used – before and after
Proper documentation will map longevity of
screens and may indicate potential
problems from reoccurring
Pre-marking will significantly
accuracy and productivity
improve
Consult washbooth suppliers as well as
state, city and local ordinances regarding
drainage and waste disposal
Consider two separate systems, or a
combination, when processing water and
solvent-based inks
PRINT TABLE
and
Urethane is the most common squeegee
material and make sure the grade selected
holds up to aggressive frit and solvents
used
Squeegee
PRESS SETUP
Material
Single durometer – straight edge
squeegees (90º corners) are the most
commonly used for glass printing
Dual-durometer blades are gaining in
popularity for fine detail applications,
particularly for smaller format printing and
demanding results
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9
High quality, more expensive squeegee
blades are generally more cost-effective as
they do a better job of printing, have more
resistance to aggressive frit/solvent
cleaning and last much longer
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Key
Elements
PRINT TABLE
and
PRESS SETUP
(Continued)
Variables
Characteristics
Squeegee
(Continued)
Guidelines
Affects ink deposit and edge resolution
Durometer
(hardness)
Edge Quality
Mechanical
Angle
Durometer ranging from 65º – 85º are
widely used for glass printing
Continuous cleaning as well as wear and
tear will increase durometer over time and
those increasing in hardness by 5º should
be discarded for demanding print quality
Most critical variable of the squeegee: keep
clean and sharp, let it rest after cleaning
and sharpening (see separate entry)
Solvents and chemicals weaken the edge;
so does printing too soon after sharpening
(see separate entry)
Set mechanically fixed angle on the
squeegee assembly bridge 10º - 15º from
the vertical position
Large depth squeegee blades will require
less of a fixed angle as opposed to those
shorter in depth
Actual print angle is an important variable
that needs to be constantly attended to in
order to render suitable print performance
Print Angle
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Angle decided by several variables:
durometer, mechanical fixed angle, depth
of squeegee from holder, pressure, offcontact and peel-off settings, mesh, image
and more
10
Comments
Softer squeegees yield more deposit but
reduce edge definition while the reverse
occurs with harder blades
Check durometer periodically to insure
hardness has not changed due to solvents
or when incrementally wearing down
Always refer to durometer by its hardness
number—not
by color
when
troubleshooting since a common colorcode system does not exist between
manufacturers
Follow manufacturer’s recommendation for
proper squeegee handling and care
For long production runs, rotate squeegees
frequently, as determined by experience, to
allow their edges to regain integrity (reduce
swelling)
Never preset more than 20º angle
mechanically under any circumstances for
glass printing
Print angle should not vary more than 5º –
10º from fixed mechanical angle and back
off pressure slightly when reducing angle
or print speed
Less angle improves edge quality/thinner
deposit while the opposite occurs with a
greater angle
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Key
Elements
PRINT TABLE
and
PRESS SETUP
(Continued)
Variables
Characteristics
Squeegee
(Continued)
Pressure
Guidelines
Comments
Pressure needed is in direct relation to
screen tension, fabric grade, off contact,
peel-off, image size, copy characteristics,
durometer and frit size to complete ink
transfer
Keep pressure at a minimum to reduce
unnecessary squeegee and screen wear
as well as image distortion and possibly
registration problems
The least amount of force is ideally
required to transfer ink through the screen,
which under suitable conditions, will reduce
overall stress in the process
Speed
Ideal speed is determined by transferability
of ink (ink flow) and shear rate according to
mesh grade and reproduction of image
detail
Probably the most overlooked variable for
consistency in deposit uniformity
Length
GANA DD – DOC – 0111
Best way to keep pressure low is by using
higher screen tension and lower off-contact
distance
Lower viscosity generally permits faster
print speed
Speed should ideally be fixed with the
same ink type and viscosity range for all
jobs
Squeegee length should be no longer than
1” (25 mm) past the image width on either
side
Fit the squeegee to suit the image, not the
frame
A blade that is too long will collapse in the
center, resulting in excessive pressure,
premature screen wear, image distortion
and uneven ink deposit
Snowplow
Consider snowplowing the squeegee a few
degrees, on either axis when printing lines
and halftones
Snowplow helps to improve edge definition
of lines by reducing the ‘sawtoothing’ effect
as well as helping to eliminate moiré
Dripless
Use feature when printing acid-etch
coatings or any ultra thin/transparent-type
coatings
The anti-drip device prevents ink dripping
off the squeegee blade onto the open
screen during the flood cycle, which will
ruin the next print
11
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Key
Elements
PRINT TABLE
and
PRESS SETUP
(Continued)
Variables
Characteristics
Squeegee
(Continued)
Sharpening
Management Care
Guidelines
Comments
A good quality squeegee sharpener is
imperative as the number one support tool
for screen printing onto any clear substrate,
such as glass and in particular for large
sizes
Frequent sharpening is perhaps the most
critical pre-press process on the production
floor but about the least considered
Prepare a detailed procedure to ensure
sharpening is regularly carried out after
squeegees have been printing and
cleaned, rested before sharpening and
then rested again before reuse
Squeegee blades are the cheapest item for
printing yet they can be the most expensive
in the process if they are not treated
properly
Clean only with water or ‘press-wash’ for
solvent-based inks and do not leave ink to
dry on them
Superior blade material will always last
longer, resist solvents better
and
significantly
improve
overall
print
performance
With solvent-based inks and aggressive
cleaning solvents, rest blades ideally for 24
hours or overnight before reuse or
sharpening
Have several sets of squeegees in the loop
of the same size so they can be rotated
during production
GANA DD – DOC – 0111
Ideally cross-train in its operation, rotate
but designate one person per shift/per
month to handle the job to yield consistent
results
Uncoil material when received, cut to size if
practical, lay flat, store away from inks,
solvents and bright lights at 68º – 77º F
(20º – 25º C)
Rest again for 24 hours or overnight after
sharpening (see comments)
Variables
Follow
sharpener’s
recommended
procedures very carefully and modify them
to suit as required
Variables listed in this section are some of
the more critical operational variables.
Please be aware that there are many more
variables associated with the squeegee
12
Some sophisticated sharpeners create
hardly any heat from friction if used
correctly, so squeegees could be reused
immediately after sharpening
Using aggressive solvents for cleaning will
unnecessarily make the edges swell and
be completely unusable until properly
rested
Consult your supplier
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Key
Elements
PRINT TABLE
and
PRESS SETUP
(Continued)
Variables
Characteristics
Floodbar
Role
Guidelines
Comments
The real purpose of the floodbar
(floodcoater or scraper blade) is not to
return the ink back to commence the next
print cycle but to determine how much the
squeegee will deposit
Squeegee can only transfer what the
floodbar has left in and on the screen
regardless of its conditions
Those that are mechanically angled at 0º
from vertical are ideal for applying heavy
deposits—and are sometimes referred to
as a ‘standard’ floodbar
Type
Set Up
Those pre-angled at 25º - 45º degrees are
better for obtaining thinner deposits and
improved image resolution/edge quality.
Sometimes are referred to as a ‘halftone’ or
‘special’ floodbar
Should have enough pressure to leave an
even amount of ink across the surface
along its entire length
Floodbar adjustments are independent of
the squeegees’, which can be very
advantageous
If the dynamics of the screen permitted
more ink coating to be transferred than
desirable, switch to an angle (halftone)
floodbar
If ink deposit is insufficient due to the
dynamics of the screen, switch to a
standard floodbar
Adjust floodbar pressure for controlling ink
deposit before changing other variables
Any nicks will print as an unsightly line
GANA DD – DOC – 0111
Edge
Edge must be straight, level, nick and burrfree
Controls
Keep control settings consistent, such as
speed, angles, pressure, etc.
13
Never lay a floodbar on its edge but rather
on its back and place a protective cover
over the edge
Oftentimes, the flooding action has more
influence on the print than the squeegee so
be mindful of its formidable power
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Key
Elements
PRINT TABLE
and
PRESS SETUP
(Continued)
Variables
Floodbar
(Continued)
Characteristics
Guidelines
Comments
Length
Extremely important that its length should
be ‘paired’ with the squeegee
A floodbar that is too long will leave more
ink coating in the middle of the screen thus
permitting the squeegee to print an uneven
deposit
Print Modes
Should ink dry too quickly in the screen
between print cycles, consider using the
‘flood/print’ mode, if available, as it keeps
the screen flooded during the pause
between cycles
Conversely, if too much ink seeps through
the screen between print cycles, switch to
the ‘print/flood’ mode of operating, which is
generally considered the normal way of
operating
Variables
Variables listed in this section are some of
the more critical operational variables.
Please be aware that there are many more
variables associated with the floodbar
Consult your supplier
Make-Ready
Before setting up a press, check that it is in
a useable state from the last job and safe
to commence make-ready - especially at
the start of a shift and in particular when a
formal handshake (handover) was not
conducted between the previous operator
Sometimes the most simplest things
forgotten
create
unnecessarily long
downtimes between changeovers
Screen tension alone determines distance
to use
Mechanical
Off-Contact
Set as low as possible to allow for a clean
release of screen from the substrate during
the printing stroke
Since larger screens typically have lower
tension, they would require higher offcontact
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14
Too much off contact will result in
excessive squeegee pressure, image
distortion, poor registration, reduced
screen life, loss of image detail and
inconsistent ink deposit
Higher tension screens will always allow a
lower off-contact distance corresponding
with less squeegee pressure; setting up the
ideal rheology for successful printing
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Key
Elements
PRINT TABLE
and
PRESS SETUP
(Continued)
Variables
Characteristics
Mechanical
(Continued)
Peel-Off
Guidelines
Comments
Shear rate of ink determines the amount of
peel-off to use, if required, to prevent a
large area of the fabric to remain in contact
with the glass behind the squeegee
Increase peel-off rather than off-contact if
high tension screens do not create a clean
separation from the glass surface
Peel should be set high enough to allow
the screen to release from the substrate to
provide a clean looking print
Nesting
To reduce wear on the screen and yield a
better-looking print, consider using nesting
supports to prevent the squeegee from
jumping when it runs on and off from the
glass surface
May also be used to register the glass
panel
Teardown
Upon finishing a production run, it is a good
working practice to leave the printing
machine in a ‘neutral safe state’ – that is
zero back registration adjustments and
cancel
any excessive
settings
or
adjustments
On the last print of a job, set the machine
so the print cycle finishes at the end of the
print stroke, thereby making it easier to
clean the screen
GANA DD – DOC – 0111
In many instances where good printing
techniques are used, nesting is not always
required – but generally used to provide a
‘safety net’
Nesting material should be the same
thickness as the substrate
As screen printing equipment can be rather
complex, insist on having handshakes (an
update of the printing machine’s state and
current/finished job) when switching
operators
Ensure correct lamp configuration, voltage
power settings and conveyor speed with
UV curing
In general terms, water- or solvent-based
inks require the longest possible resident
time in the heating section that will keep up
with productivity, which will then afford the
lowest temperature setting – for a more
efficient way of operating and reducing
glass exit temperature
If cooling is used, ensure the air is not
restricted, too warm and that the exhaust is
working properly
Usually the reverse with UV, ink is exposed
for the shortest possible time to crosslink
and not over cure
Ensure heat settings configuration is
correct for the ink type, color, deposit
thickness and conveyor speed
Drying or
Curing
High tension screens will always reduce
the dependence of peel-off and excessive
squeegee pressure
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Key
Elements
PRINT TABLE
and
PRESS SETUP
(Continued)
ENVIRONMENT
Variables
Characteristics
Mechanical
(Continued)
SOP
Conditions
Print room
Guidelines
Each of the printing equipment’s settings
and conditions should be properly recorded
for each type of print need and ink medium
used (standard and transparency etch) so
that they can be repeated by any operator
Generate a full working set of operating
procedures (SOPs) according to practices
and techniques employed when results
produce good-looking prints with minimal
hassle in make-ready and production
Consider building a separate room around
the printing operation to keep factory dust
and dirt away
Comments
Some form of standardized procedures
become necessity when mechanizing an
artistic printing process into one that is
more
controllable,
repeatable
and
manageable by everyone involved
To keep the print room continuously clean,
minimize traffic by making it ‘Authorized
Personnel Only’ and, as necessary, supply
operators with cleanroom outerwear (coats,
hats, bootees, etc)
Consistency to maintain actual or practical
working conditions, regardless of what they
are, is more important than the ideal values
stated if they cannot be continuously met
Cost to provide some form of a separate
print room is greatly outweighed by
spectacular print results and superior
production performance
GANA DD – DOC – 0111
Temperature
Ideal range 68º – 72º F (20º – 22º C)
Humidity
Ideal range throughout the year 50% - 60%
R/H
Pressure
Atmosphere slight over pressure, 1¾ in (45
mm) over water column
Air Quality
Quality filtered air with at least four
changes/hour although six should be
considered
16
Consider using
viscometer
an
industry-recognized
Consistency in viscosity promotes quicker
changeovers for short custom jobs and
makes it easier to track problems as they
arise
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Key
Elements
ENVIRONMENT
(Continued)
Variables
Conditions
(Continued)
Guidelines
Characteristics
Static
Reduce the effects of static electricity by
using antistatic mats and coats as well as
consider separately grounding equipment
as necessary
Access
Ensure access doors open outwards to
prevent dragging factory dust particles from
entering
Enamels, referred to as ink or paint, should
be thinned and/or mixed prior to use within
the supplier’s viscosity range
Enamel (ink)
Viscosity
Establishing a workable range will enable
operators to use the same machine
settings
Always filter the ink before used,
particularly if ink recovery is practiced, to
prevent hard dried pieces from being
printed
Dried up, hard ink can not only ruin an
otherwise good print, but can also pop the
screen
Screens
As above
If materials cannot be stored in this type of
environment, they should be brought into
the printing environment at least 24 hours
prior to being used and allowed to
acclimate to the print room-type conditions
Enamels
As above
As above, but recommend 48 hours prior to
use
Consider hanging them on the wall or
provide a rack for each size including
paired floodbars
As with floodbars, squeegees should never
be rested on their edges but left laying on
their backs blade uppermost
Use a tin side meter to ensure the glass’ air
side surface is uppermost for architectural
and appliance glass printing
When printing on the tin side of glass, the
ceramic frit will react with the tin and may
cause discoloration or mottling. This could
give the appearance of a defect or poor
print quality
Recovery
Material Storage
Squeegee
Floodbar
Others
Air Side
GANA DD – DOC – 0111
Comments
and
17
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Key
Elements
ENVIRONMENT
(Continued)
Variables
Others
(Continued)
Characteristics
Guidelines
Comments
Tin Side
Use a tin side meter to ensure the glass’ tin
side surface is uppermost for automotive
glass printing
The tin side is desirable for automotive
applications, due to the reaction with the tin
and the silver conductive ceramic enamel
Antistatic
Consider
using
antistatic
devices
particularly as the glass enters the print
room from the washer
Refer to suppliers’ recommendations
Ink Feeding
Consider suitable access for operators to
pour ink into the screen at the floodbar
end, according to size of the press and
layout
Inspection
Consider need to inspect print immediately
after printing before it enters the dryer
Work with OEM initial recommendations
Highly recommended to allocate space for
such checking since it will enable operators
to make print adjustments as necessary
For information on additional reference resources including the GANA Glazing Manual and other Glass Informational Bulletins visit GANA
website: www.glasswebsite.com.
The Glass Association of North America (GANA) has produced this document solely to provide general information as to general guidelines for
screen printing on flat glass. The document does not purport to state that any one particular type of screen printing process or procedure should
be used in all applications or even in any specific application. The user of this document has the responsibility to ensure that architectural glass
constructions meet building code and other specific project requirements, GANA disclaims any responsibility for any specific results related to the
use of this document, for any errors or omissions contained in the document, and for any liability for loss or damage of any kind arising out of the
use of this document.
This document was developed and approved by the GANA Decorative Division – Printing on Glass Task Group and approved by the Decorative Division membership and GANA Board of
Directors. This is the original version of the document as approved and published in January 2011.
GANA DD – DOC – 0111
18
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