Digital Prints

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Mastering Digital Printing
The light doesn’t have to be a high-noon bombardment of Florida sunshine either.
Although direct and indirect sunlight or unfiltered fluorescent light tends to accelerate
fading more than incandescent light, the weak light from a 75-watt bulb hanging near a
print can be enough to fade it as well. It all depends on the duration and the intensity of
the light exposure. High intensity for a short time has the same effect—in theory—as low
intensity for a long time. (See reciprocity failure above.)
One problem with lightfast testing is that it may or may not take into account all the other
factors that cause prints to fail. Is it really just the light that makes a print fade? Or is it
also the humidity, the temperature, and the air quality? As you might expect, it’s usually
all those things and possibly even others that have yet to be discovered.
Another problem with lightfast tests is that the methods and test protocols vary from tester
to tester. From endpoints to reference display conditions and light-source choices, there
is no uniformly accepted way to conduct a lightfastness test (also see more about this in
“Your Mileage May Vary”). Creative Memories’ Dr. Mark Mizen has a good analogy to
fit this state of affairs: “It’s as if Ford decided to measure gas mileage only going downhill
while Chrysler chose a level road. Both methods would give a gas mileage, yet the numbers
would be very different and would not allow a fair comparison.”
You can see why this testing business is so tricky.
Other Tests
Other important tests that are currently being carried out or being developed by standards
groups include:
■ Gas Fading (for air pollutants, air flow, and ozone)
Photographer Stephen Livick and
colleague Bill Waterson collaborate on
sunlight fade tests. This image shows
the results of 700 hours of full sun
exposure (approximating 70 years on a
275-lux, daylight-illuminated interior
wall) on inkjet prints with five different
protective coatings. The original,
uncoated strip is at far right (A7).
According to Livick, the white spots are
from the pigment or manufacturer’s
white base simply flaking off.
Courtesy of Stephen Livick
www.livick.com
and Bill Waterson
waterson@ainet.com