Offset to Aqueous Inkjet...the Basic Differences
Many times we see companies spending millions of dollars on high-speed aqueous inkjet equipment for billing, transactional, direct mail and various marketing material. Inkjet is a wonderful and disruptive technology that is truly a game changer in the printing market. I received an inquiry last week from a print broker who was seeking the differences in the two processes. He is seasoned in selling printed offset, but was not completely knowledgeable in the conventional processes nor high-speed aqueous inkjet.
His print producer is a conventional offset print house looking to accent its production, as well as start running short-run variable data on inkjet technology. He was particularly uneasy about inkjet. I assured him, yes, it can be very scary for sales folks whose lives have been spent selling traditional offset. But it is also an exciting time which, if understood, can be very profitable.
He understood that inkjet variable data and imaging was a great game changer, but asked “So, what’s the basic difference?” For both processes, there are two things that really affect everything...ink and paper.
Since he has focused his career on selling print and has not been on the offset process side for quite some time, we started with Differences 101.
Ink and Paper...
Traditional Offset process involves “squeezing” a layer of high-viscosity “tacky ink” to a blanket or flexible plate; then to the substrate surface. Offset ink sits higher on the paper surface, which allows more color to reflect from the surface producing a very large color gamut. Offset inks can dive into the fibers of the paper, but this condition is mostly caused by the formation of paper and not because of the offset inks. Offset ink is compatible with common coated (totally sealed) and uncoated paper grades; no special papers are needed. Drying is either cold-set (dries by absorption into the sheet), or heat-set, utilizing drying lamps.
Inkjet Printing is a non-contact process that “mists” a very low-viscosity “watery” ink chemistry less than 1mm from the sheet. Currently there are two aqueous inkjet fluids from which to choose.
Pigment inks contain solid, opaque particles that are suspended in aqueous chemistry. The 0.1 to 2 micron particles link together on or just below the paper surface. Qualities such as hue, saturation and lightness will vary depending on the pigment type and chemistry. Pigment inks provide long-term durability.
Dye-based inks contain dyes that dissolve in the aqueous chemistry. When applied to an uncoated substrate, the dye colorant is absorbed into the paper. This produces more dot gain with less color reflection and vibrancy on uncoated grades. Depending on the printer’s drying process, dye inks mostly have a larger color gamut on inkjet coated papers than pigment.
Both pigment and dye inks prefer what is called “inkjet treated papers”—a fast drying, low absorbent, pre-coated/treated paper surface that quickly slows the colorant absorption into the paper, keeping the color closer to the surface. Inkjet inks require porosity in a sheet, which means that a standard offset coated grade will not dry properly using aqueous inks. Inkjet coated papers are made with some porosity to allow absorption of the aqueous fluid. Ink dries by absorption unless the machine includes air or IR dryers. There are high-speed aqueous pigment inkjet printers that jet a “pre-coat or bonding agent” fluid previous to the image. This allows more of the pigment colorant to stay on the surface of an uncoated sheet.
This explanation suited him well, as he felt he had a better understanding of the basics and is now yearning for more information. He has called back two times since then.
Do you currently sell both offset and inkjet? Are you confident that your sales staff understands the basic differences? Not knowing will affect your sales and integration of new technology.