2003 Larry Berman, All Rights Reserved
Henry Wilhelm is a true leader
in the field of image permanence. Involved in photography since childhood,
Henry became interested in the preservation of photographs in 1963 while
working in the hot and humid jungles of Bolivia while serving in the
Peace Corps. In '66 he served as an assistant to Ansel Adams during
one of Adams' photo workshops in Yosemite National Park, and in
'72 he received the first of his patents on archival print washers
for black and white fiber-based prints. In '81 Henry received
a Guggenheim Fellowship for what became a 10-year study of color print
In recent years, Henry has been a consultant to many collecting institutions,
including the Museum of Modern Art in New York and Bill Gates'
Corbis, where he served as an adviser on the long-term preservation
of the Corbis Bettmann photography collections. Henry and Carol Brower
Wilhelm are the authors of the landmark 744-page book, "The Permanence
and Care of Color Photographs: Traditional and Digital Color Prints,
Color Negatives, Slides, and Motion Pictures," published in '93.
Generally regarded as a leading authority on ink jet permanence, Henry's
accelerated testing of ink jet media has given today's photographers
empirical evidence of the archival quality of today's ink and
Shutterbug: Your work as a pioneer in the field of
image permanence has shown you both the good and bad about ink jet printers.
How can a photographer pick an ink jet printer that they can trust to
make prints that will be around for decades?
Henry Wilhelm: The simple answer is to pick a printer
for which print permanence data is available for the ink and media combinations
used for that printer.
SB: Where can that data be found, and how much credence
should someone give to a manufacturer who claims a given expected lifetime
of a print?
HW: I think the important thing is that first the manufacturer
would describe or at least have available a description in some detail
how the tests were done. In the case of HP and Epson, both of those
companies have primarily relied on our company (Wilhelm Research) to
do the test evaluations and then they make that information available,
or steer people to our website or to publications that are quoting it.
Canon, with its initial launch of its photo printer, also did that.
More recently, Canon has been publishing self-generated data that uses
similar but not identical test procedures. I think that one important
issue here is that the paper itself, particularly with the dye-based
inks, can have a significant impact on the permanence of the image,
and not only in terms of light stability. In other words, there is not
just one single permanence figure for a printer with its ink set.
SB: Is it safe to assume that manufacturers always
use their own papers with their inks in testing?
HW: Yes, although manufacturers themselves often will publish data just
for their paper that does the best, even though they have additional
SB: Would it be safe then to believe that by using
the exact ink and paper one can probably achieve the same kind of archival
HW: Yes. Most of the quoted numbers have been for exposure
to light on long-term display. In general, the data have been for prints
framed under glass. I think we also need to talk about susceptibility
to ozone for prints that may be exposed to ambient atmosphere for long
periods of time. Prints that are not framed under glass--for example,
the classic refrigerator display conditions or prints tacked to the
wall in your office--may have different stability figures, especially
smaller prints that will never be framed under glass. There is a special
concern about porous or microporous papers with dye-based inks and the
greater susceptibility of these papers to ozone.
I think, from the reader's standpoint, the simple way to distinguish
between porous and microporous and swellable papers is that if the paper
package says "instant dry." That's pretty good assurance
that it is a microporous type. And if the printer is using dye-based
inks, which the majority of current desktop photo printers are using,
then you can probably assume that your print on microporous paper probably
has a high susceptibility to ozone. You have to be careful there.
The Squeak Test
SB: Tell us a little more about swellable vs. microporous
papers and what is the squeak test that we've heard about?
HW: The squeak test is a simple means of identifying
microporous high-gloss papers. Just rub your finger across it--if
the paper feels like it squeaks and sort of grabs your finger, that
is caused in part by the paper being so absorbent that it absorbs the
tiny traces of oil and moisture off your finger, which act as a lubricant
on smooth surfaces. Nevertheless, I think looking for the designation
"instant dry" is a good way to identify microporous paper,
and will probably be more useful for most people. It is a pretty accurate
way to distinguish microporous from swellable.
The swellable ink jet papers use an ink receptive coating on the surface
that is more akin to traditional photographic gelatin. In fact, gelatin
is one of the polymers frequently used in swellable papers--usually
in combination with others. When the ink hits the surface of the print
the image receptive coating literally swells up. In areas of high-density
ink coverage it can take a number of minutes, or even longer depending
on the ambient humidity and the paper and ink combination, before it
actually feels dry to the touch. The ink and its dyes are absorbed into
this now swollen layer and then, as the water evaporates, it shrinks
back down to its original surface thickness with the dyes to some degree
encapsulated in it. That encapsulation provides a significant amount
of protection from the ambient atmospheric gases.
There is a parallel with traditional photography here. Traditional black
and white photographs have an image composed of pure metallic silver,
which looks black because its very finely divided filamentary structure
absorbs light instead of reflecting it. But if it wasn't for the
protective affect of the gelatin emulsion and the overcoat in which
that silver layer resides, black and white photographs in many environments
would only last a day or two before the image would become stained or
Pigment Vs. Dye Based
SB: Can you tell us about pigment vs. dyed-based inks?
HW: Traditional color photography has always used dyes
in its films and print material, whether it is Ektacolor, Fujicolor,
or any kind of type-C print. Even Ilfochrome or Cibachrome are dye based.
It actually has not been possible to use pigments in most color photography
processes. In the distant past there was tricolor carbro and a few other
esoteric processes that used color pigments. But they are very difficult
In a nutshell, dyes are dissolved in the ink vehicle, or dispersed in
the image-forming layer, at the molecular level itself. Consequently,
they are very, very small. Pigments, on the other hand, are insoluble
and are much larger particles. As classes of colorants go, pigments
certainly have the possibility of having much higher light stability.
They are also usually much more resistant to ozone, or gas fading, as
it's referred to. Pigments have other advantages as well. They
have very little short-term drift. In other words, when you print the
image, after just a very quick initial drying phase, the image will
change very little over time. For people using color management, making
profiles of each paper and ink combination, that's a very important
consideration. Dye-based images tend to drift more. And if you are using
a tightly based color management system, then that may create some real
Print Dry Down
SB: Earlier you had talked about microporous instant dry papers,
and compared them to the swellable encapsulating papers that take a
while to dry. Will that longer drying process actually affect how the
image looks when it first comes out of the printer compared to when
it is totally dry?
HW: Yes, to some degree it can. But the same problem
can occur with some dye-based ink and microporous
SB: So you can look at a print when it first comes
out of the printer, which is just great, and a couple of hours or a
day later come back and say, "Wait a minute, that's not
the same image that I saw before."
HW: That would be true. Now, it's a different
kind of change, it's not fading, normally. But it may shift in
color balance somewhat. The density may change slightly and not necessarily
uniformly over the density scale.
SB: So, one can't just simply say that a print
gets lighter or darker or shifts in a certain color direction?
HW: No. And it would depend very much on a particular
ink set and the paper it's on. It is difficult to generalize.
Some are much more stable in this respect than others. With traditional
color photography, people could not evaluate color prints until they
were completely dry. Papers like Ektacolor or Fujicolor changed rather
remarkably in the course of drying so there is certainly no similarity
here. However, what is different is that in traditional color photography
once the print is dry coming out of an RA-4 process, then it is highly
stable in terms of this short-term drift phenomena. In other words,
in weeks or months later it will not change. With a dye-based ink jet
print that's not necessarily so, and it partly depends on the
environment you're in. If you are a photographer in Miami, Florida,
where the humidity is very high, this may be a more serious problem.
On the other hand, pigmented ink systems have very good short-term drift
behavior. Pigmented ink systems also tend to be waterproof.
SB: Tell us about the differences between the systems that
use four, six, or seven inks. Is there a difference in the stability
or is it simply a tonal issue?
HW: Well actually, it's both. Historically the
use of dilute magenta and dilute cyan inks would typically cut the light
stability or display permanence by a factor of two or even three times.
Those inks were more susceptible to fading on exposure to light. Now,
with Hewlett-Packard's newest system used in the Photosmart and
other HP printers using dilute magenta and cyan inks, that is no longer
true. In fact, the six-ink implementation of that is much more stable
than the HP four-ink implementation on HP's photo papers.
The rational for using the dilute inks, whether it's dye based
or pigment, is to improve smoothness of tone. When you see a printer
rated at 1440x720dpi, those dpi figures or resolution numbers are actually
true only at maximum image density. The only way an ink jet printer
can make lighter tones from darker inks is to leave droplets out, or
to some degree by varying the droplet size. In an image produced even
with a nominally high-resolution printer using only four inks, that
leaves a feeling of granularity or lack of smoothness to the image.
This is especially true of the tonal gradations in lower densities,
like the highlights in someone's face, for example.
SB: Is that why you can see a dither or some kind of
dot pattern in some four-color printers?
HW: It's a feeling of what I call a granularity
or texture that doesn't have the same smoothness. The use of dilute
inks, the magenta and cyan, allows many more dots to be laid down by
the printer for the same density and that means there is less white
space in the lower densities. In addition, all other things being equal,
color saturation is also improved with six-ink systems because in middle
and lower densities there is less desaturation of colors because of
the visual mixing of the white space between ink droplets that occurs
with four-ink systems. This is particularly important for portraits
or landscapes that have subtle skies. Many types of images benefit greatly
from this. And that is why the dilute inks were developed in the first
place. It's better for photographic reproduction. Yellow ink is
very low in image contrast, so there really hasn't been any perceived
benefit to having a dilute yellow.
Now, with the newest printers, there is a seventh ink, a dilute black,
which gives two benefits. One is that in the near neutrals it allows
significant replacement of the color inks with black inks through much
of the tonal scale. It's called GCR, or "Gray Component
Replacement." That allows for a more accurate and linear reproduction
of the neutral scale. Also, because the black ink, especially in pigments,
tends to have higher stability, it can increase the overall stability
of most images, especially in terms of color balance shift. It also
allows a satisfactory printing of black and white images, which was
more difficult before. It also reduces what is called metamerism or
metameric failure, in which a color print may look significantly different
when viewed under different light sources, for example, daylight vs.
tungsten, halogen vs. fluorescent. You certainly want to minimize that
to mimic what human vision does. The use of the dilute black has improved
SB: What other factors should photographers consider when they
choose a printer, paper, and ink?
HW: I think there are several other performance distinctions
between dye-based inks with microporous papers, dye-based inks with
swellable papers, pigmented inks with microporous papers, and pigmented
inks with swellable papers. One is that at this point in time there
really isn't a completely satisfactory high-gloss media for pigmented
inks. They are certainly satisfactory in terms of image permanence,
but they do exhibit what is referred to as differential gloss. In other
words, the gloss of the image is to some degree a function the density
of the ink. If you look at the reflection of light off the surface of
a print, you will notice that. This is something traditional color photographs
never had a problem with. The gloss of your Ektacolor or Fujicolor print,
if it's a high-gloss surface, looked completely smooth. Dye-based
ink jet is capable of printing on high-gloss papers, either swellable
or microporous, and exhibiting little if any differential gloss.
At this point in history it's difficult to say, overall, which
system is better, particularly for small prints--what we think
of as 4x6 photofinishing prints--where most people seem to prefer
high-gloss prints. That's been a tradition, certainly in this
country. If that is what your goal is, at this point in ink jet technology
you're pretty much restricted to dye-based inks. And with the
microporous or instant dry papers, which have wonderful image quality,
very good water-resistance, and the instant dry feature, the shortcoming,
which is potentially very serious, is susceptibility to ozone or other
Again, pigmented ink sets like those used with the Epson professional
photo printers or the Hewlett-Packard large format printers, in general
have better light stability, and good water-resistance. But again, from
a photographer's point of view, one of the biggest drawbacks is
the lack of a completely satisfactory high-gloss paper. Now for larger
prints, this is not so much of a problem for many photographers because
they prefer the sort of semigloss or luster surfaces anyway. So this
gets down to a personal preference question, and I think you do see
a sort of split in both the printers and the way photographers are using
them. In general, for people who use small prints--traditional
photofinishing snapshots--dye-based inks may be preferred or even
essential in order to get the perfectly smooth high-gloss surface.
SB: Is lamination a possible solution?
HW: Lamination can be a very good solution. It's
just that, certainly on the desktop, and even for fairly large-scale
use of small prints by photographers, it's an extra and potentially
expensive step. The laminator itself may cost more than the printer.
SB: Going back to glossy surface vs. luster, can it be roughly
broken into two camps--the amateurs who are shooting for snapshots
and passing prints around to their friends and the professionals who
are shooting something that they would like to have outlive them?
HW: I think that's a good point. We can draw
an analogy from traditional photography where the wedding/portrait business
historically has not used high-gloss photography papers, but rather
the luster or semigloss. And the transition to ink jet with pigmented
inks is much easier. It's the same kind of surface basically that's
been used all along. And once large prints are framed under glass, it's
much harder to see the
SB: What about fingerprints?
HW: Fingerprints, as far as we can tell with these
products, do not have a major impact on ink jet permanence.
Fingerprints certainly did affect the initial types of dye sublimation
prints before the manufacturers began protecting them with a clear coating
after the image layers were in place. Over time the oils from your fingers
could cause the dyes to start migrating physically. The early dye sub
prints were also extremely susceptible to contact with plasticized PVC
sleeves, such as people have in their wallets or PVC notebook pages.
I think all of this shows a parallel to the completely new modes of
deterioration, such as susceptibility to ozone that are possible in
any new imaging technology. Traditional black and white RC prints are
another example of this. They suffer from a kind of deterioration in
which low-level oxidants are generated by the top polyethylene layer
of the paper, especially when framed under glass, which then in turn
attack the silver image. That's a mode of deterioration that did
not exist with traditional fiber-based black and white prints.
It's really easy to forget that the entire ink jet printing field,
at the photographic quality level, is a very young field and could be
dated to 1994 on the desktop when Epson introduced the first 720dpi
printer. For a field that is less than 10 years old I think that an
astonishingly amount of progress has been made.
Most of us in the image permanence field, including myself, never really
expected to see a six-ink dye-based photo printer with the level of
light stability that HP has achieved with their newest ink set and paper.
That was a major breakthrough. I think that there was sort of a foregone
conclusion that pigments would be the ultimate answer, and I think that's
not so clear now. On the most stable paper combinations, in these cases
HP Premium Plus Photo Paper, the light stability of prints on display
is comparable to the pigmented inks in the UltraChrome ink set by Epson.
SB: Now that gets us to the next question, which is about the
color gamut or the color range. The consensus has long been that the
colors in the pigment sets were not as rich or as vibrant as the dye-based
ink sets. Is technology changing that?
HW: The previous pigmented ink sets that the Epson
used, which was known as the archival ink set and used in the 2000P
and the 7500 and 9500 large format machines, was what we considered
an extremely high light stability pigmented set. With many types of
media it would go past 200 years in our standard display conditions
test. Epson came to believe, in part because of the very question you've
asked about the color gamut of pigment vs. dyes, that photographers
wanted higher color saturation and larger gamut and sacrificed some
of the light stability of the previous set to achieve that. And that's
sort of a classic tradeoff that color photography's always dealt
with at one level or another, that if you could ignore permanence completely
that virtually every system would have a larger gamut and higher saturation
than actual systems on the market do.
The initial pigmented sets used by HP on their large format machines,
like the 5000 or 5500, are extremely high stability six-ink systems
that are capable of being used for a reasonable length of time, even
in outdoor graphics. Epson's UltraChrome ink set could be thought
of as the first pigmented ink set introduced by a major producer designed
for indoor use with a reasonable gamut, which takes advantage of the
permanence advantage that the pigments have. They also have advantages
like short-term color drift, resistance to high-humidity environments,
and so on. I think we are seeing very interesting developments in the
field right now where there are viable pigment systems that most photographers
feel have adequate color gamut. If any difference is really noticed
with the UltraChrome ink set it's probably not so much the color
gamut as it is maximum density, or the depth of the blacks, which kind
of anchors the sense of brilliance of the image.
SB: What is the single biggest factor that causes print fading
with today's ink jet printers?
HW: Especially with any of the dye-based printers,
whether it's Epson, HP, or Canon, one really needs to be aware
that the choice of paper can have a huge affect on the outcome as far
as permanence. It's not just an image quality question.
An example that we always cite is our tests with Staples Premium Glossy
Photo paper. The new HP printers with their ink set and HP Premium Plus
Photo Paper received a 73 year rating. The same printer and ink with
the Staples paper was rated as lasting only two years on display! It
can be that dramatic.
Our company, as a matter of policy, has pretty much stayed away from
the image quality questions, leaving that to people like yourselves.
I will say that it's a very multi-parameter problem.
SB: Experimenting with different ink and paper combinations
can yield a rich range of image tones, but can yield unexpected image
stability issues. I found I really liked the way Canon printers produced
black and white images on Epson Heavyweight Matte Paper, but the images
were not very stable.
HW: Yes, I think a good example of that is if you like
the flat matte papers as many photographers do, that if you were to
print on Somerset Enhanced using dye-based inks, you can produce absolutely
stunning prints with a high D-max. However resulting prints are extremely
unstable with dye-based inks on every platform, including the Iris printer.
After you make the print and look at it you'll say great, but
six months of display later it may look anything but great. There's
no way to know that out of the box--it gets back to the point where
if you don't have specific information available about the permanence
of your ink media combination, you're potentially going to have
I think one of the real differences that has developed in photography
in the past few years is the ability of the average photographer to
have the ability to make their own color prints. That was simply not
possible before without a major investment in equipment. Most photographers
took their film to a lab. It could have been a minilab or a higher-end
professional lab. But the choice of paper usually was not one that the
photographer made. They might make a choice of surface, like high gloss,
semigloss, or luster, but the paper was the same. Now that has completely
If you walk into CompUSA or Best Buy, there's a huge shelf full
of paper and the end user is now actually choosing and buying paper
to make color prints, and that never existed before in photography.
That's one of the things that's become confusing because
people have been offered a huge array of different papers at different
prices, most of them claiming to be excellent in every respect. You
even see it on the Kodak Ultima ink jet papers, which, on the front
of the package, says it makes "long-lasting prints" as sort
of a general statement.
Certainly one thing I would advise people to be very aware of is that
the papers made by Kodak and the other
third-party companies--that is other than the printer manufacturers
themselves--are all advertised, without exception, as being suitable
for all printers. It means that in the formulation that they are not
optimized for any particular ink set or printer. They are using a "one
size fits all" approach and that means that they don't fit
any of them well compared to what the printer manufacturers can do because
they design their papers specifically for their ink sets.
I think that nowhere is that more evident than in HP's new photo
inks and Premium Plus Photo Paper, which is available in both a gloss
and matte surface. At this point in history, I would consider that ink
and media match to be the most highly engineered match of an ink set
to a paper in terms of permanence. And it kind of points where I think
the field is going. These are highly specialized products and, particularly
with the dye-based inks, a proper match between ink and media is critically
This is all something we didn't have to deal with in traditional
photography. People were buying process RA-4 color prints and they were
made with either Kodak or Fuji paper, or it might have been Konica or
Agfa paper. But whatever the lab used, that's what you got. Now
you have almost infinite combinations of inks and papers that can be
used. And I think many photographers will do exactly what you just described.
They will try different papers looking for a certain surface or tonal
quality at a price they like and when they find that combination that's
what they will print on. But image permanence is sort of a hidden thing.
You can't see how long an image will last just by looking at the
Henry Wilhelm's informative
website is www.wilhelm-research.com.
Chris Maher and Larry Berman are photographers, writers, and web designers.
Visit their websites www.BermanGraphics.com