Plastics Decorating Magazine Technical Author – Q&A – Scott Sabreen Question: What is the difference between Continuous Inkjet and Drop-on-Demand Inkjet? Question: What is the difference between Binary and Grayscale Inkjet Printing? Question: What types of inks can be used for Inkjet Printing?

1. aSK THE EXPERT
Plastics Decorating is pleased to feature this section in our magazine in which you
(our readers) can ask industry experts specific questions about plastics decorating. To ask one
of our columnists a question, send an email to QA@petersonpublications.com.
By Scott Sabreen,
The Sabreen Group
Inkjet Printing
Question: What is the difference between Continuous Question: What is the difference between Binary and
Inkjet and Drop-on-Demand Inkjet? Grayscale Inkjet Printing?
One of the earliest inkjet technologies, dating back to the In Binary inkjet, every pixel on the substrate to be marked
mid-1980s, is termed Continuous Inkjet (CIJ) printing. At is either covered with an ink drop or its not, thus an either/
that time non-contact CIJ was used for general purpose print- or binary choice. In contrast to Binary, Grayscale inkjet has
ing of variable information on flat packaging and direct mail- the capability to fire a range of individual drop sizes. Some
ing (paper stock, cardboard, and related porous substrates). printhead manufacturers have the capability to fire up to 16
A few, but limited, plastics applications used CIJ but in levels of grayscale. Grayscale inkjet can be preferred versus
general, there was poor ink adhesion. With CIJ, printheads Binary for exceptionally high resolution as measure in dots-
incorporate a single jet and can run at very fast speeds using per-inch (dpi).
air-drying solvent-based inks, although alternative heat-cure
inks also are used. As the terminology implies, CIJ operates Question: What types of inks can be used for Inkjet
in a “continuous” stream mode. CIJ is a very fast inkjet Printing?
method but lacks high quality printing. Depending upon the specific type of inkjet printhead, UV
(ultra-violet) inks, solvent-base inks, water-base inks, and
The newest generation of inkjet technology is termed Drop- hybrid inks can be used. Ink chemistry is a critical factor
on-Demand (DOD), or piezoelectric DOD inkjet. It is DOD when determining which type of printhead to procure for
inkjet printing which provides newfound excitement for each application. Inks are normally formulated to be used in
high resolution, variable information, decorating on two- specific printheads. This is due, in part, because printheads
dimensional and three-dimensional plastics applications. At will function best when the optimal visco-elastic properties
present its primary usage remains in printing flat products are achieved including temperature, viscosity, drop size, and
such as billboards and signage. shear forces just to mention a few of the important variables.
Many printheads can utilize either UV, solvent-, or water-
DOD inkjet also is a non-contact printing technology, but base inks. n
in contrast to CIJ, dots of ink are precisely controlled which
yields very high resolution, 600 to 1400dpi and higher. Scott R. Sabreen is founder and president of The Sabreen
Individual droplets of ink are jetted from small diameter Group, Inc., which is an engineering company specializing
vessels directly to a specified position on the substrate to in secondary plastics manufacturing processes – surface
create the image or alphanumeric text (and machine vision pretreatments, bonding decorating and finishing, laser
codes). The vessels can range in quantity from 128 to 768 marking, and product security. He has been developing new
and greater depending upon the print area and speed require- technologies and solving manufacturing problems for over 25
ments. Thus, the main difference between CIJ and DOD is years. He can be contacted at (888) SABREEN or by visiting
the multi-nozzle drop-on-demand printhead nozzles that are www.sabreen.com or www.plasticslasermarking.com.
in intermittent use.
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