The Effect of Paper Color on Ink Color
I received a color quiz from
an ink company (Flint Ink) many years ago. It has a little
window through which you can see fifteen paper swatches.
On the cover is the question: "Which swatches are printed
with the same ink"? I have showed this quiz to numerous
people over the years, and most point out two or three or
five colors they think are the same. What is the catch?
The colors used on all paper swatches are the same. It is
the paper color of each swatch that changes.
Most, but not all, inks are transparent.
Light travels through the ink film, bounces off the substrate
(paper, vinyl, or whatever), and is reflected back to the
eye. The color of the paper dramatically influences the
perceived color of the ink.
The color quiz includes samples of
coated and uncoated sheets: coated including dull, matte,
gloss, and cast coated, and uncoated including Kraft paper
(natural and bleached). The coating makes a difference in
the color as do the impurities (such as the lignin in groundwood
stock) and the formation of paper fibers. Bright sheets
(sheets that reflect back a large amount of light) make
the blue of the ink quiz appear brighter. White sheets (sheets
that reflect back clear, white light without a particular
color cast) make the ink appear whiter.
Clearly this is not something that
can be adequately conveyed in words. In some cases the differences
are subtle, and in others the blue looks vastly different.
I think it is enough to realize just how dramatically paper
can affect the perception of ink color.
With this awareness, consider that
some inks are opaque (opaque white, for instance) and are
not affected by the color of the substrate. This can be
used to your advantage, as will be shown in the next section.
Four-color process inks are always transparent.
The best way to achieve your aesthetic
printing goals and not be unpleasantly surprised is to ask
for an ink draw-down on the stock you are using. Or, choose
a stock and specific inks based on sample books printers
and paper companies are eager to provide. These books will
show various effects (duotones, for instance) on particular
paper stocks, with or without varnish. Using such books
you can see what your printed piece will look like (for
the most part) before you commit ink to paper. Discuss your
goals with your printer, ask for samples, and even consider
attending a press check.
Everything stated above need not be
a problem. On the contrary, using the reciprocal influence
of ink and paper, you can create unique effects that provide
superior design as long as you understand and control the
effects of paper on ink and ink on paper.
For example, you might expect a halftone
printed on a gray stock to have highlights only as bright
as the unprinted sheet. If so, you would be mistaken. In
fact, you can underprint an opaque white on a portion of
a subdued, gray sheet, then, after the ink has dried, you
can print a gray and black duotone over the opaque white.
If, for example, you had preprinted the opaque white under
a figure bathed in sunlight in a portion of the photo, this
figure will seem to jump off the page once the duotone has
been printed. The underprinting of white will make it seem
as though sunlight were actually lightening this portion
of the image.
You can do the same by underprinting
match red under a four-color image of flowers. When the
red has dried and you surprint the four-color flowers, you
will see just how much more dramatic the flowers will be
than if printed only in process inks. The match red underprinting
will sharply increase the saturation of the red flowers
in the image.
If you approach layered printing in
this way, you will pay more than for four-color offset since
you will be using more printing units (ostensibly on larger
presses). You will also need multiple passes through the
press with drying time in between. But for special printed
products, such as an annual report, this can make for a
superior design product that really stands out.
As with the first section in this issue
of Quick Tips, consider the paper stock and the opacity
of the inks. Consider also whether you will wet-trap or
dry-trap the inks. Wet trapping means running the base color
and surprinted colors within the same pass through the press.
This allows for a more subdued color effect (while also
requiring more printing units). The opposite, dry-trapping,
means waiting until the first pass of inks has dried, and
then printing the second pass of inks. Printing four-color
process over dry-trapped opaque white, for instance, will
allow for the maximum "pop" of the four-color
image off the page. The effect is far more dramatic than
with wet-trapping, which would only provide a subtle lightening
of the four-color image.
Finally, consider adding a dull and/or
gloss spot varnish to separate portions of the images to
make them advance or recede. Or consider adding varnishes
tinted with ink for a subtle, almost ghostly effect.
[Steven Waxman is a printing consultant. He teaches corporations how to save money buying printing, brokers printing services, and teaches prepress techniques. Steven has been in the printing industry for thirty-three years working as a writer, editor, print buyer, photographer, graphic designer, art director, and production manager.]