THE DATA FRONT

90 | l&l
Coating strategies
HP Indigo’s digital label press series requires specially coated substrates to key inks. Andy Thomas
looks at those requirements and the choice between in-house coating and pre-coated substrates
Achieving the best results on the HP Indigo ws4000 and
WS6000 press series is a factor of the ability of the special HP
Indigo ElectroInk technology to key to the printing stock – and
this requires a special topcoating.
The special formulation and delivery of ElectroInk will not
give acceptable results on untreated stocks, or on materials
treated with conventional print surface primers. Based on
nano-particles of color suspended in oil, ElectroInk technology
delivers a thin ink layer to the print substrate, which depends
on a surface pre-treatment to achieve good ink key.
In a recent presentation at the Digital Label Summit in
Barcelona, speakers from Avery Dennison and ExxonMobil
presented data demonstrating how critical is a properly
engineered coating for ElectroInk to key properly to film and
paper substrates.
For coatings to be officially certified by HP Indigo for use with
its ElectroInk, they must meet strict parameters established
by the company. Certification of high-value self-adhesive
laminates has proven to be a helpful driver of self-confidence
for label printers new to the technology.
Comments Gerard Geurts, industrial media manager
worldwide for HP Indigo: 'Our imaging process is different, so
we want to assure our customers that the materials we certify
will consistently perform on our machines. HP Indigo certified
materials meet all our lengthy test parameters, not just for ink
adhesion, but also for machine wear-and-tear. Our ‘stress test’
enables us to evaluate the way in which a printing substrate
affects the press itself and all the related print consumables –
ink, plates and blanket.'
Given the increased availability of specialty coated
laminates, when should label converters coat their
own materials in-house?
An interesting case study is provided
by Eccoprint in Hirtshals, Denmark,
a third-generation family-owned
narrow web converting business, which orders standard stocks
for its UV letterpress Nilpeter press alongside specially coated
materials for the company’s ws4050.
Comments Eccoprint managing director Jan Viberg Elleriis,
'With our Indigo press, we can really respond fast to our
customers' urgent needs for short-run self-adhesive labels.
Sometimes we get the files in during the morning, and deliver
the printed labels in the afternoon.'
Elleriis is a regular customer for the Fasson Digital Indigo
range: 'The quality of the topcoating is excellent, and we get
first-class print results'. The rolls are supplied press-ready
– there is no need for any additional in-house processing
or priming – so material waste and press downtime are
minimized. But there are times when a particular facestock is
not available in the Digital Indigo range, or when his customer
needs order turnaround in a matter of a few hours.
In situations like this, Elleriis topcoats material himself on
the finishing station of the Indigo press, using the broad
inventory of standard Fasson labelstocks he keeps for his
non-digital work. While this gives Eccoprint the capability of
turning round an order quickly, it can be costly. Adding an extra
offline process to the production of the finished labels ties up
equipment, labor, time, and energy – costs which all contribute
to the final price of a label – and creates more set-up and
rewind material waste. 'It is obviously more cost-effective to use
ready-coated labelstocks for short-run work -- but sometimes I
have to take the other route!' says Elleriis.
An alternative to using the finishing station of the Indigo
press to topcoat is to purchase a small off-line coater – again,
additional investment, and often additional material waste.
‘Coating quality may not be as consistent as
a precisely-calibrated industrial coater,
which may adversely affect print
quality,’ says Fasson.
HP Indigo's WS6000 digital press
Labels&Labeling