an Ink |
Types of Inks
Standard pad printing inks are made of resins, pigments, and thinners.
The resin system, also referred to as the binder,
is what forms the dried ink film. There are
numerous resin systems for pad printing inks.
Pigments are the colorants dispersed
in the resin system.
Thinners (or solvents) adjust the viscosity
of the resin 1 pigment mixture, and give the
ink its printing characteristics.
Catalysts (or hardeners) may be added
to certain inks to make them harder, glossier,
and 1 or to increase adhesion. Inks that use
catalysts are referred to as "two component
inks". Single component inks don't require catalyst.
Some pad printing inks can be either one or
Other additives that may be necessary
include retarders, adhesion modifiers, matting
agents, and anti-static agents.
Retarders are really just very slowly
evaporating thinners that are used to slow the
drying or tacking of the ink.
Adhesion modifiers are used to increase
the adhesion capability of certain ink types.
In some cases adhesion modifiers and catalysts
can be added to ink at the same time.
Matting agents are used to lower the
gloss level of ink when necessary.
Anti-static agents are added to help
In addition to standard solvent based pad printing
inks there are baking inks, oxidizing inks,
sublimation inks, and UV cured inks that are
used in pad printing.
Baking inks are usually two component
inks requiring a special catalyst and sometimes-special
thinner. These inks, which must be baked or
flame cured, are used on glass, ceramics and
Oxidizing inks are used where weather
and chemical resistance are necessary, in addition
to flexibility. They cure by absorbing oxygen
from the surrounding atmosphere. Their use is
limited due to their slow drying nature.
Sublimation inks involve a special process
whereby the substrate is heated to become porous
after the ink is applied. The dyes of the ink
pass into the substrate, changing the substrate's
color. Once the substrate cools the ink is essentially
"sealed". These inks are commonly used on items
like computer keyboards, where even two-component
inks can lack the necessary resistance. Sublimation
inks are very difficult to color match.
UV cured ink, by design, contains no
evaporative solvents, making it very difficult
to transfer via pad printing. In addition to
being difficult to pick up and transfer, UV
ink lacks opacity, and thus doesn't work well
on dark colored substrates.
Choosing an Ink
Most ink manufacturers provide technical information
that recommends ink or inks for nearly any substrate
you'll run across. What you need to do first
is find out exactly what the material you intend
to print on is made of. The more specific, the
better. It doesn't help your supplier's technical
people much if you tell them that you want to
print on "black plastic", since there are hundred
of substrates that could fall under that description.
Once you know the substrate, you'll need to
find out what characteristics the ink must have.
Asking your customers questions like these can
do this: How well must the ink adhere? Does
the ink need to meet specific abrasion, chemical
and weather resistance specifications? Are there
any specific concerns about the potential toxicity
of the ink? What are the ink's drying and curing
requirements? Can the supplier match the colors
I want? Is any type of certification required?
After gathering this information you're ready
to contact suppliers to discuss your project
and obtain recommendations.
Most pad printing equipment and ink manufacturers
have applications laboratories staffed by experienced
technicians that can either recommend which
ink you should use based on the information
you give them, or they can test print your parts
in their lab. Having your parts tested is usually
no charge, unless you insist on having your
image printed, in which case a nominal fee is
usually applied. Even then, many manufacturers
will apply the costs of testing toward the purchase
of any equipment you buy as a result of the
Once you've got your ink, make sure you read
the manufacturer's technical information and
carefully follow their instructions for mixing,
thinning, drying and curing. All too often people
fail to follow the proper procedures for mixing,
and I or fail to follow drying and curing schedules,
only to have their parts fail testing. Starting
Out Pad printing is part art and part science.
To expect to be able to purchase a machine,
choose the right cliche', pads and ink, and
then print successfully overnight is unrealistic.
You don't need to have experience with any printing
process, or be a chemist to succeed, you just
need to take the time to learn the variables
involved in the process, and how to control
The first thing to do is contact pad printing
equipment manufacturers and discuss your intentions
with them. In doing this you'll not only learn
if your project is feasible while gaining information
about the process, you'll also get a feel for
which manufacturer you want to deal with.
Feeling confident with a manufacturer is more
important than getting the lowest price. The
costs of poor service and technical support
will end up costing a lot more than you'll ever
save if you allow cost to be your sole determining
factor in choosing a manufacturer.
Your manufacturer should be willing to work
with you from beginning to end on your project.
They should be willing to test print your parts
and provide you with samples to prove their
machines and methods work before you agree to
Finally, make an effort to obtain proper training
by visiting the manufacturer's facility, having
them make a video specific to your machine (even
if it costs money), or having them come to your
facility to train you and your operators there.
It will prove to be well worth the costs.
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