Faded photograph prints

Mark D. Hanson <curator [at] aeromuseum__org> writes

>I have inherited a puzzling problem. We have a hallway along one
>wall of which a photo timeline runs. The hallway is lighted by
>fluorescent tube lights in enclosed fixtures. It is an interior
>hallway with no windows. The photos are color scans of primarily
>black and white originals printed in color on glossy photo paper
>from an ink jet printer. The prints are then dry mounted onto foam
>core.
>
>The photos appear to "randomly" fade at an alarming rate. We have
>tried using different papers and different printers, but to no
>avail, we have tried to isolate a correlation to lighting hotspots,
>but none exist. Photos fade just as quickly in darker areas of the
>hallway as in brighter ones. We have tried control groups of
>multiple picture using the same print settings, printer, ink
>cartridges, box of paper, and dry mounting materials and technique.
>Nothing seems to work. ...

When you say some pictures "randomly" fade, does that mean that
multiple printings of the *same* color scan, printed *exactly* the
same way, on the same side of the same paper, are fading
differently?

If yes, then I'm stumped, though you are putting them through quite
a few potentially interacting processes. For diagnostic purposes,
try eliminating, rather than controlling the variables. (Don't mount
at all, pin them side by side, no HVAC vents nearby, etc.)

If no, (in other words, *different* color scans, with the same image
processing, print settings, etc., are fading differently) then it
*may* be the result of the color separation process. The visual
black that an ink jet printer produces is often built of more than
just black ink. Different combinations of the inks that your printer
has available can be applied to produce the visually same color of
black. These inks often have different fade-resistance.
(This is why full color posters that you may see in a store window
often look purplish or blue. The offset printing inks fade at
different rates. Yellow goes first, so the overall appearance
becomes more purple, sometimes in just a few days. Then magenta (an
intense, pinkish red) goes, leaving only the cyan (an intense blue)
and black. Cyan and black offset inks are much more resistant to
fading, so there it is: the sky is still blue, but the grass is blue
also and the orange sunset has almost vanished. If exposed long
enough, sometimes the cyan will outlive the black.)

In your case, "color scans of primarily black and white originals
printed in color", by the time the scanner color separation (RGB) is
translated to printer CMYK (your printer may also be using light M,
light C, etc.) your blacks in different images may be built of
different inks, and therefore responding differently to the same
conditions.

There is an entire field of fine art ink jet printing devoted to the
printing of black and white photographic images that are resistant
to fading and other appearance issues that can show up in black and
white work. The color separation process is carefully controlled and
often an ink set with multiple, different black inks is used. A
professional fine art printing shop could produce the prints for
you. ($) Printing shops that produce outdoor display work could also
help you with this issue.

>... Will the
>laser printer solve our problem?

Think of typical ink jet as a watercolor painting: thin coating,
mostly pigment, with enough water-sensitive binder to hold it on the
paper.

Think of laser printing as an oil painting: heavy coating, pigment
deeply enveloped in a water-resistant medium. As oil painting is
more fade resistant than water colors, so is laser printing more
fade resistant than ink jet. (Though there are oil-based ink jet
processes for outdoor work...)

Watch out when you mount the laser prints, heat can melt the ink.


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                  Conservation DistList Instance 18:36
                 Distributed: Sunday, January 30, 2005
                       Message Id: cdl-18-36-003
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