Page 175 - Graphic Design and Print Production Fundamentals

Graphic Design 163
causing the chains of molecules in the ink to bond and solidify instantly. UV ink does not dry from
exposure to air, nor from heat. Once the UV ink has been cured, however, it is very solid and quite
durable.

For commercial use, UV inks tend to be popular for outdoor uses such as banners and signage. Indoor
signage is commonly printed using UV as well because of its durability and rub resistance. Since UV
inks dry instantly, they can be removed from the printer and handled much sooner. UV inks sit mostly
on top of the surface of the substrate, and because of their solid bond are more prone to cracking if bent
or folded. UV is not a good choice of ink where flexibility of the substrate is required.

Latex Inkjet

Latex ink is a newer formulation that has exploded onto the inkjet printing scene in the last few years.
Latex inks are water based and cure primarily through heat, but more importantly, they are not subject
to moisture damage once cured. This is because the pigment is carried by the latex molecules, and once
the latex has bonded to the substrate, the pigment stays intact. Latex printed products dry immediately
and are ready to use as soon as they come off the print device.

Latex inks are used in many commercial applications, particularly where outdoor durability and
flexibility are needed. One of the many common uses of latex inkjet printing is in imaging car wraps. A
car wrap is a flexible adhesive material that is printed flat, then stretched or wrapped around the contours
of a vehicle, usually for marketing or advertising purposes. Figure I.1 in the introduction of this textbook
shows an example of a car wrap. Because of this flexibility, latex printed signage can also be adhered to
rougher surfaces such as wood or brick. The popularity of latex can be attributed to a previously popular
inkjet formulation that is solvent based.

Solvent Inkjet

Because of the rise in popularity of latex ink over the last few years, there has been a great decline in the
use of solvent inkjet inks. Formerly, this was the type of ink needed for flexible, durable printing. Solvent
inks are formulated using solvent as a carrier for the pigment, and as the solvent dries, the pigment
remains bonded to the substrate. A big concern for the use of solvent-based printing is the release of
volatile organic compounds, or VOCs. These VOCs are released into the atmosphere during the printing
and drying of solvent prints, and have to be vented outdoors so as not to pollute the workspace. Even
newer eco-friendly inks still release VOCs, albeit at a lower level. Some areas have environmental laws
that restrict the release of pollutants into the air (United States Environmental Protection Agency, 2000).
Customers often complain about the smell of solvent prints, particularly when used indoors. Because
of this, solvent inkjet is primarily chosen for outdoor uses such as large-format signage, banners, and
car wraps. Solvent can be very economical, and while the quality isn’t as sharp as UV or aqueous, it
is excellent for very large projects that will be viewed from even a moderate distance. Pressure on the
solvent ink market comes because most of these uses can now be achieved with latex inks as well, and
the industry has seen a divergence between companies that still use solvent or eco-solvent inks and those
that are switching to latex.