Digital Prints

174
Mastering Digital Printing
Remember that this was just one way to do a test. I could have, instead, used a different
light source, run the test longer, tested different inks on the same paper, instrumentmeasured
the samples before and after, or changed any of the other factors. I wanted some
quick, basic information to make an informed decision about what material combinations
would best meet my needs for a specific display condition.
Others do it differently. Mark Gottsegen suggests a quick-and-dirty test: “Make a sample
and expose half to daylight (sunlight preferred) in a south-facing window while keeping
the other half in the dark. Compare after a month or two. This, of course, is very subjective
and not very scientific. Using one of the ASTM standards Blue Wool Test Methods
such as D5398 or D5383 is much better, and not that expensive nor hard to do.”
Joy Turner Luke is one who follows the ASTM D5383 guidelines. In a recent test, she took
inkjet-printed test specimens and exposed them to natural daylight (including direct sunlight)
on racks suspended one foot below skylights facing upward and to the south in a
heated and air-conditioned room. A card containing the eight ISO Blue Wool References
was placed on each test board. The test was complete when Blue Wool 3 faded to match a
Munsell 5 PB 6/4 color chip and Blue Wool 6 also showed a color change. In this case, it
took 139 days. (At the same time and as part of the same test, another set of identical specimens
were hung on an interior wall out of direct light in the same building for five years.)
The skylight specimens were taken down and rated visually by three human observers.
Figure 5.13 reproduces the appearance of both sets of exposed specimens.
Figure 5.13 Joy Turner Luke’s
exposed inkjet test panels and, at top,
the ISO Blue Wool Reference card.
The three panels on the left of each set
were hung on an interior wall in
indirect light for five years. The three
panels on the right of each set were
exposed to daylight coming through
skylights. The far right-hand section of
each skylight panel was covered with a
lined metal bar to protect the colors
from light. At bottom is the Magenta
that bleached under the skylight.
Courtesy of Joy Turner Luke