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| September 2005 issue of PRINTWEAR |
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How
to Select New Equipment or Update Existing Equipment
by Douglas Grigar, Master
Screen Printer
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(A version of this article originally appeared
in the September 2005 issue of PRINTWEAR.)
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Searching the Internet for screen printing
equipment or attending a trade show - such as one of next year’s
Printwear Shows - most often reveals the “smooth-and-sexy”
side of screen printing. What you don’t see is all the
prep work that goes into making art and screens, the chemicals required,
and all the other choices of materials it takes to create that colorful
shirt you watched taking shape on that monstrous octopus called a press
(see Figure 1).
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[Figure 1: Your first impression of
a screen printing press may be akin to a horror film. While screen printing
is not a “mission impossible,” there is a lot to learn and
many skills to develop.]
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A Warning
Screen printing is not something to be
entered into lightly: it represents an investment in time, education,
and responsibility. To be honest, screen printing is a relatively inexpensive
business prospect to enter, but a commitment to the technical aspects
is essential, along with a devotion to the time and effort in skills
development and trade education. Commitment seems to be the largest
component of making a screen printing plant successful.
Starting or adding a screen printing operation
is a business in and of itself. If you are adding screen printing to
an existing established business, you can expect double the effort invested.
Seldom do I see plants with little or no business; rather, I see what
could be called “jumping into the deep end” where a business
owner who expected a few hours a day of print productions instead labors
under months of long hours attempting to keep up with the demand. If
it all looks too easy, you may not be looking deep enough at the entire
process and business needs.
Most screen printers learn the basics of
the craft in “the school of hard knocks” along with a large
investment in “trial and error.” A few educational classes,
seminars, and even on-site training will often shave months
off some of the more painful lessons. No one could say that training
will totally fill in for the time needed to learn the “feel”
for a squeegee, or become familiar with the overall process. I can say
with confidence, though, that any investment in training will
be worth ten times the cost and time spent gaining a few insights into
the proper techniques. (Visit www.thegrendel.com
for one of the industry’s leading comprehensive and intensive
screen printing training program. -Ed.)
Art to Screens
Screen printing and, in particular, garment/textile
printing, demands the greatest amount of control over the print, held
directly in the hands of the artists and pre-press technicians in charge
of screen production.
Art production can look easy but simply
learning the features of art-production software is not enough to make
the average user a screen print “artist.” It is an undeniable
fact that artistic talent has an intangible element and that creativity
and visual execution from a talented artist is dramatically different
from that of a mere computer “user.” Without art produced
in a particular way that is specific to screen printing, the print will
not be of the quality demanded of the job.
Once the art is transferred to positives,
appropriate screens and mesh must be chosen in order to make a stencil
that is capable of printing the desired image. Suggestions from experienced
artists on the best printing methods for the art should be carefully
attended, as much art is designed to print in a particular fashion to
create the final visual effects. Screen print artists who have themselves
printed for many years, or have coordinated art for many years, are
a valuable source of information for the industry.
The expansion of the Internet and the growth
of the freelance-artist market has made it possible (and quite easy)
to obtain “high-end” art - from artists with years of screen
printing experience - without actually have an art department in-house.
Print designs from the best artists in the industry are available to
even the smallest shops. Designs that were once the exclusive domain
of large shops with expensive art departments are now available to any
business with a desire and Internet access. Myself and many manufacturers,
suppliers, and screen printing professionals have lists of dependable
and talented free-lance artists just waiting to build a design that
will work for you.
Because positives must be of high contrast
and high quality, be sure to choose an output device that can produce
a positive with the maximum contrast from light to dark areas as possible
(see Figure 2). Currently, RIP-driven inkjet printers and thermal-image
printers give great results at reasonable prices. Without high-contrast,
high-quality positives, quality screens are nearly impossible. Toner
printers are forced to print on special paper or coated film that is
not optically clear and often will not obtain dense enough coverage
(especially in the centers of large areas), causing light pass-through
and higher exposure times in order to overcome the less-than-clear film
or paper (or vellum). Choosing a good positive-producing printer will
save you time and much grief later.
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[Figure 2: Be sure and choose an output
device (printer) capable of printing a good high-contrast (clearest
of clear areas and darkest of black areas) positive. Note how the light
black of vellum on the left has much less contrast that the dark black
of clear film on the right.]
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Screen Quality and
Production
While some may argue the “good enough”
point of view, no professional is foolish enough to argue that wooden
frames perform better than rigid aluminum frames, or deny the user control
and high performance of retensionable frames.
I like to use the example of wood frames
as the disposable plastic cigarette lighter, low in initial cost but limited
in performance and, over time, the most expensive product due to that
same low performance and the disposable nature of the product. Rigid aluminum
frames are like the dependable, standard, liquid-filled refillable lighter:
strong, reusable, and will last a lifetime of proper use, at a true mid-ground
of price and performance. The last option would be the retensionable frame,
in many ways similar to the gas-rechargeable, high-performance, windproof
lighter, the best of performance for the extended long life of the product;
it has the highest initial cost, but its long life and high performance
make it the least expensive over time. (Don’t have any experience
with cigarette lighters? Good for you! Still, I hope you catch my drift.)
The second part to the total screen equation
is the mesh fabric and its use in the print shop (see Figure 3). The basic
rule of thumb is three-fold: Choose a standard for your shop and stick
with the same brand and physical methods; choose to have a wide selection
of mesh-thread counts in your standard choices; and choose a quality product
from a manufacturer with a good reputation. For more information on mesh,
see the articles “Mesh-Selection Primer” and “Screen-Mesh
Characteristics” in the December 2004 and March 2005 issues of Printwear,
respectively.
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[Figure 3: Mesh and frame choices are
most likely the most important product decisions in the entire process
of setting up a shop.]
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One of the most important equipment needs
in an entire shop is a screen-drying cabinet and its complimentary light-safe
storage cabinet. For reasons unknown, the drying cabinet remains the most
forlorn and forgotten piece of necessary equipment in screen printing.
It is sad to see thousands of dollars of shiny new screen printing equipment
in the same dusty room where wet screens are drying next to a filthy old
fan blowing every speck of contamination off the floor onto the freshly
cleaned and degreased mesh.
Screens must be processed
quickly and in a clean environment free of dust. The most effective means
to accomplish this is the drying cabinet. Information on how to build
an effective screen-drying cabinet is included in an article entitled
“How to Build a Screen-Drying Cabinet” in the September 2004
issue of Printwear.
The Truth About the Press
The real work in screen printing is performed
by the stencil, mesh, and squeegee, with the most important part
being the screen (the mesh and frame as a unit).
For screen printing on garments and textiles
we must have machines capable of holding the material in place and printing
it. Once fabric is removed from the adhesive on the platen, there is no
way to repeat the exact positioning again as the fabric changes dimensions
when removed (see Figure 4). Because of this need to remain on the platen,
elaborate machines engineered to provide reliable platen and screen alignment
are required. Manual or automatic screen presses are simply devices to
hold the screens in the correct position over the platens and to consistently
line up each time for a clean print.
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[Figure 4: Once removed, a garment
cannot be placed back on the platen in the exact same position for the
printing of additional colors.]
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While choosing a press is a balancing act
involving the quality needed, the budget, and a wide range of features,
any seasoned printer will tell you that buying a quality press regardless
of the price is never a bad decision. Some features that are considered
standard now are “all-heads-down” capability (in my book,
a misused term that, instead, should be “precision print-to-head-platen
alignment”), multiple rotor arms and platens (what was once known
as a “speed table” for flashing), and “micro registration”
of the screen-clamp heads.
The main selection consideration
should be “what am I going to print?” Make an educated choice
based on your needs. If you are only going to print one- or two-color
designs that do not require close tolerance, you may be able to function
profitably using a “low-end” press with few features and construction
of uncertain quality. If, on the other hand, you need precise control,
you will need to consider the quality of the press construction and the
advanced features available in a “production-level” press.
Little details such as inexpensive gliding metal bushings versus more
expensive sealed anti-backlash bearings, the quality of the construction,
and inexpensive compressed-wood versus aluminum or steel platens, are
all part of the decision-making process. Contact users of presses you
are considering - obtain the necessary information from the suppliers
with whom you are talking - and ask not just about the press but how many
types and brands of presses they have used in the past, and if they are
familiar with the newest features and models available. Research is the
key to a good decision.
Thinking About the Future
While you may be able to print any job on
a single-platen-arm press, the time needed to produce the goods will be
greater. Simple math will tell you that, if your production time for a
multi-color job is lower, after only a few such jobs the time-value lost
with a single-color press will be greater than the price of a multi-color
rotor-arm press.
Of course, there are many more decisions
to make and things to think about, but I wanted to go over a few of the
items that seem to be missed the most when new and upgraded equipment
are purchased.
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