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| June 2004 issue of SCREENPRINTING |
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Optimizing Prepress for Special-Effect
Garment Printing
by Douglas Grigar, Master
Screen Printer
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(A version of this article originally appeared
in the June 2004 issue of SCREENPRINTING.)
Thi article was so popular it was translated and prited in at least
four languages. The above cover was from a Spanish translation. We only
host the English verision on this site.
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The
First Approach (Special-Effect Garment Printing)
High-density, caviar beads,
flakes, puff... do those words make the hair on the back of your neck
stand up or make the art staff roll their eyes?
Was your first attempt at screen
printing specialty inks or printable products from a small kit with little
research, and rushed though with an already stuffed schedule?
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Judging process and results requires knowledge
of the most basic concepts of screen printing procedures, equipment,
and design, along with their contribution to the final product.
While each individual specialty product
deserves a complete report, this article focuses on the basic concepts
you can use along with your own experiences and good judgment to make
a rational critique of past results, and develop a process plan for
each future product.
Designing for Specialty Products
An artist must make themselves familiar
with the use and effects of specialty products so that they can produce
art that maximizes the visual and textural effects of those products.
Screen printing specialty inks are best
used to support or accent a design by effect or texture. How much of
a design is made up of specialty ink depends on the features of the
specialty product itself. For instance, high density inks work best
on smaller objects, text, and lines that are not extremely thick and
do not span large areas. On the other hand, flocking, caviar beads,
and christalina will not work as well in small objects. Also, thin lines
as small printed areas will not contain enough product (or have enough
adhesive to hold enough product) to be visible and will not take full
advantage of the light-refracting or texture-creating effects of the
products.
Products Effect Numbers of Colors
and Print Order
Designers need to take into account that
specialty products often have to be printed last in the print order,
and be removed from the press to have additional product applied. Print
order can dictate many aspects of a design, not the least of which is
the number of colors available for use in that design. Products that
are raised from the surface of the substrate can interfere with the
printing of other colors that are too close to that raised edge (see
Figure 1).
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[Figure 1: High density inks can raise
the level of the mesh and create a tiny “tent” effect that
can cause colors later in the print order to form blobs or smear, and
fail to print correctly.]
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| Large flakes, caviar beads, and
flocking are often applied to printed adhesives off press or on one of the
last print positions. While specialty attachments, presses, and devices
are available for some products (like flocking applicators for automatic
presses), the first introduction most shops have to adhesive-locked products
are often labor intensive off press methods.
Ink Color and Opacity
Underlay colors can be used for special effects,
but care should be taken to communicate the desired effects for production.
Using reflective or flake-bearing inks as an underlay can create attractive
designs with a deep layered look. Choosing the overlay colors on reflective
bases requires inks that are translucent and allow light to pass through
them to give that deep look like custom painted show cars. Dense opaque
colors will be needed for creating the “layered birthday cake”
effect and for lenticular prints with high density inks.
Design Impact
Designing with specialty inks means taking
into consideration the effects of the products and making allowances for
the behavior of the product. Using puff inks as an example, designs may
need a gap of additional open space (as small as ¼- to 1-point
in thickness) around the product to expand as needed. Puff inks can be
used under other colors to produce multi-color puffs. Results of puff
ink underlay are the raising, texturing, and lightening of the colors
on top. Large areas of puff ink can curl and bend, while thick layers
can expand in unpredictable and inconsistent ways. The level of expansion
can be magnified by the addition of larger amounts of puff additives.
Effectively creating designs that work well
with specialty product characteristics involves conceptually following
the printing process in reverse from the finished product to curing, printing,
screen making, positive production, and back to the design concept.
Don’t Be Afraid to Try Something
New when Special-Effect Garment Printing
An artistic note about “correct use”
of specialty products: never be afraid to do something “wrong”
to achieve a visual effect! It is never “wrong” to take the
properties of the product in mind and deliberately change the recommended
procedures for a creative effect. Curing, washability, and adhesiveness
to the substrate must be considered; i.e., testing is mandatory. A grand
artistic effort that will not stay on the product is costly and embarrassing,
but creative use of new products puts your shop ahead of the curve.
Positives and Stencil Production
The extended exposure time and tight registration
needed for making specialty product stencils requires high quality positives.
The highest contrast of dark to clear areas of the positive (D-Max to
D-Min) will be needed to prevent light passing through the dark areas
of the positive. Less-than-quality positives are aggravated by extended
exposure times. Lenticular printing requires the best of press, screen,
and positive registration. Without good positive registration, no step
afterwards will be able to produce anything more than lackluster results.
Screen Printing Mesh Consideration
Choosing mesh with ink born particles means
choosing a mesh with large enough openings to pass specialty products
onto the substrate. Glitters, flakes, small solid particles, and even
the thicker inks can demand screen printing mesh that has larger openings
and possibly larger thread diameters. A closer look at the behavior of
ink born particles brings us to choosing openings that are at least double
the width of the largest particles. The best choice for passing particles
through mesh would be openings triple the width of the largest particles
to prevent any possible multi-particle wedging that would cause a blockage
(see Figure 2).
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[Figure 2: Three particles side-by-side
allow ink pressure to break the particles out of the mesh and onto the
substrate (2a). Too small of an opening will cause the particles to
wedge together and clog the pathway (2b).]
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| The Dynamics of Screen
Printing Mesh and Special-Effect Garment Printing
All inks benefit from higher tension levels
on screen printing mesh, but high density inks simply require higher tensions
to perform well. High density depends on thick layers of ink produced
from thick stencils that raise the mesh above the substrate. Mesh is a
dynamic material that will flex and stretch greatly under the pressure
of an equally dynamic and flexible squeegee. The greater the span from
one edge of a thick stencil to the other, the greater the concave effect
created by the flexible squeegee and stencil until the mesh contacts the
substrate (see Figure 3). The highest tension levels on mesh help widen
the printable span, but the largest open spaces guarantee concave prints
with thick ink deposits on the edges and thin areas in the centers.
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[Figure 3: Large spans of open area
in the stencil allow the squeegee to press the mesh lower in the middle
until stopped by the substrate, creating a concave shape.]
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| Adhesive Products
Adhesive products must be layered thick enough on the substrate to provide
sufficient area to hold the particles to the printed product. Using caviar
beads as an example, the best adhesion is when a significant amount of
the beads are imbedded into the adhesive (see Figure 4). Manufacturers
are glad to give the specifications of recommended adhesive thickness
for their products.
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[Figure 4 : Caviar beads provide the
best wash-fastness when imbedded into the adhesive to at least half
of the diameter of the spheres.]
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| Lenticular Printing
The most famous (or infamous) use for specialty products such as high
density ink is lenticular printing. The lenticular printing effect is
created by layering a grid or lines over a logo (Figure 6b) and printing
a layer (or several layers) of high density ink directly and exactly over
the first grid with cut outs in the extended shape or letters of the design
(see Figure 6a).This creates a raised image that becomes visible when
viewed from an angle (see Figure 5) and disappears when viewed from a
direct 90 degree angle (see Figure 6c).
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| What Can Be Expected From
Special Effect Inks (Special-Effect Garment Printing)
Because
special effects inks have specific properties, experimenting with custom
mixes and procedures may not create the effect that is expected or desired.
For instance, metallic inks or puff additives such as christalina may
create an undesirable result. Once again, testing is mandatory.
The Frankenstein Monster
The old saying of ‘less is more’
often applies to the use of special effect products. Just because a shop
may develop techniques to print multiple products onto one design does
not justify doing so. Often, using more than one specialty product in
a design becomes distracting, and the confusing overload of products diminishes
the visual impact of the special effects.
The Final Product and the Customer
Remember to take into consideration the customer
and the final use of the garment, including the care, washability, and
durability of the product. Designers must communicate to the customer
the general properties of products, costs, and production limitations.
Customers need to know that some special effect products are not as durable
as standard inks, and also need to know proper washing and care techniques.
Learn to Walk Before You Try to
Run
Finally, the best and often only way to successfully
produce goods using specialty products is to set aside time to test, practice,
and experiment with products new to your shop. Creative design work and
careful testing will create a great product and satisfied customer every
time.
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