Home' FLEXO Magazine : January 2016 Contents SETTING PROPER EXPECTATIONS
Today’s digital presses do not have the ability to do everything a flexo
machine can. This lack of parity between the processes is expected
to continue for years. The key to success is to make the customer
understand the advantages digital printing can provide, along with the
qualitative differences. One of the greatest differences is color gamut.
With a large number of ink units available, a flexo press can print any
color, including metallic and special effect inks, but the digital press is
limited to a fixed set of colors and limited special effects.
Setting proper customer expectations is easier with precise contract
proofing. If the proof clearly represents the final product exactly—in-
cluding what people can expect with a fixed set of colors or limited
special effects—then the expectations are clear. The proof also exists to
mediate any conflicts after the fact. The prepress department needs to
perfect the process of making contract proofs that represent the press
exactly. In many cases this requires many more profiles to be made
than currently used. Using contract proofs in this manner also places
additional requirements on the pressroom to assure that the printing
equipment is operated in a repeatable manner.
Historically, digital printing was not capable of a high level of repeat-
ability, but this has improved in recent years. As new digital printing
equipment is evaluated, the repeatability and ease of keeping the press
on track should be a key criteria in any new purchase decision. It will
always be impossible to set proper expectations if the printing process
is not predictable.
Setting customer expectations is much easier with precise contract
proofing and process control in the pressroom. New tools exist that of-
fer predictive profiling technologies that make this process much easier.
It’s commonly known when the overprint behavior of the inks or ton-
ers is significantly disparate—as the case between flexo ink and digital
ink—then uniform appearance can only be achieved by reseparation.
Curve adjustment (G7) does not address the colorimetric differences
of overprints, including orange, green, violet and most of the saturated
colors within the digital printing system. The most accurate method
of performing these reseparation tasks is through the use of device
(Note: Device link profiles are a digital map of two specific processes to
each other, without connection space L*a*b* conversion in the middle.
Every color in the flexo process has a “best fit” color address in the
digital process. The device link profile allows the optimal method of cre-
ating precise color match between fundamentally different ink systems.)
Device link color transformations (usually PDF to PDF) are the most
reliable methods of performing the complex reseparation tasks neces-
sary to achieve uniform appearance between disparate color printing
methods. Thousands of packaging files are converted every day with
this technique. For years, it has traditionally been used to reseparate
offset to flexo, or gravure to flexo, for example.
Now, tools made it easier to create the specific device link profiles
needed to perform the reseparation task. This new technology also
unlocks the door of expanded gamut (EG) digital printing, too. As the
available gamut of digital printing presses increases, visual match to
analog gets closer to process parity, increasing digital print acceptance.
A larger gamut is still needed, but the ability to precisely utilize this
gamut is equally important. Traditional color management methods
are not up to the color management task of utilizing the emerging EG
digital printing equipment.
SPOT COLOR MATCHING/COMPLIANCE
Within the device link profile for a given press/substrate combination
is the “map” of which spot colors can be printed and which cannot.
There are two components of spot color matching. The first is know-
ing which colors can and cannot be achieved. The second is knowing
how to mix the available colorants in the digital press to achieve the
best compliance to the specified color—and engineering that color
recipe for optimal color consistently. Color accuracy is less valuable if
the press cannot sustain that color over the length of the run. In some
cases, color accuracy (Delta E) may be sacrificed for color stability.
New device link based spot color tools are emerging to assist the pro-
fessionals with managing these reseparation variables. Emerging EG
reseparation technology addresses future needs, but also works well
for existing CMYK based digital printing systems.
If the preceding four business objectives have been met, then this cru-
cial fifth goal can be achieved. Key tools include reseparation of data,
contract proofing and precise profiling. Cross utilization can happen
once the printing methods achieve process parity. The goal, of course,
is a process agnostic workflow. The same product should be able to be
printed side by side regardless of the printing process. This is the holy
grail of color management. Until recently, this was not considered
“Purchasing equipment that cannot
participate in cross utilization
becomes a ‘process island’ and
creates inherent underutilization
and prolonged ROI.
JANUARY 2016 | FLEXO 51
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