Just as with conventional darkroom photographs, the care, feeding, and longevity of inkjet prints has been subject to a certain amount of misinformation. So what else is new? Some people think digital media are so durable that one need not even worry about the matter; others make dire predictions of imminent failure. Both extreme points of view are based on old and obsolete materials, data, and notions. Both have been proven wrong.
To begin with, you should understand that there's a huge variety of print materials and inks out there. Some of them really are crappy. I'm going to assume, for the sake of argument, that you actually are seeking out the more long-lived media. The best independent source for information on that is Henry Wilhelm's website, Wilhelm Imaging Research. The worst is often an ink or paper manufacturer's website.
In this article I'll be quoting lifetime numbers for prints made with Epson Ultrachrome inks, like the ones Charlie Cramer is using for his Print Offer prints, but the general principles will apply to all inkjet prints, dye or pigment (although their lifetimes may differ from Ultrachrome). I'm also assuming indoor display at normal light levels.
Under those conditions, the worst "good" print paper I know of is Epson Velvet Art, a rather primitive material by current conservator standards, It's rated at 35 years display life, unprotected (I'm going to round everything off to the nearest half decade, because, honest to god, two digits of precision is way too much in this field). Everything else checks out at 45–70 years. This is not fabulous, but it's still in the ranks of the very best of the traditional color darkroom prints, including Ilfochrome and dye transfer.
Fortunately, we can, and we will, do better. The reason:
No prints of any value should ever be displayed without protective glazing. Dust, dirt and other sorts of aerosol and particulate matter in the environment will settle on the surface of the print if you don't cover it. Cleaning inkjet prints is especially difficult, but you really don't want to be cleaning the surface of any photographic print. Given the nasty stuff that dust and particulates can adsorb on their surfaces, don't offer them any chance to attach themselves to the print.
Putting prints behind regular framing glass or acrylic improves the display life by 50–100%. That increases the range of display lives from 75–120 years, with 85–100 being typical. That's excellent. UV glass will improve that by another 60–100%, but that hardly makes UV glass a requirement; we've already entered the range of museum-standard permanance well beyond what you could be confident of achieving with a traditional print. I would only recommend UV glazing in the most extreme circumstances, such as a known high-UV environment. It doesn't hurt, but it's awfully expensive.
Recommendations have been made for "airtight" or sealed framing, to protect prints from gaseous compounds that could attack them. First, no such thing exists; second, it's a bad idea to even attempt it.
A "tight" frame will not prevent external gaseous pollutants from diffusing in, but it will tend to concentrate any compounds that are generated or outgassed within the frame environment. This is a known hazard for prints. In fact, the vexatious silvering-out problem with untoned B&W silver RC papers only occurs with framed prints. In general, more damage has been done to photographs and art prints over the ages by "protective" materials than anything else, simply because they are in close proximity to the artwork*. Tight framing is very dangerous.
It also doesn't work. On the timescale of decades, you cannot make a hermetically sealed frame at any reasonable price. Hazardous gaseous pollutants will diffuse in through any available path at a rate sufficient to attack the print. It doesn't take a lot, and they've got a long time. Once you've protected the print from aerosols and particulates—and simple glazing does that—you've done all you can reasonably do.
People have investigated truly airtight framing. It's an area of interest because it was determined, a good quarter-century ago, that essentially all light-fading in photographic prints involves hydrolytic or oxidative reactions. If you can exclude oxygen and water from the print environment, even exposure to UV-rich light doesn't cause prints to fade significantly faster than they do in the dark. If you can figure out how to frame your prints under dry nitrogen and make sure they stay that way, light fading becomes a thing of the past.
Problem is, there's no way to do that at any kind of affordable price, not when you need to keep it that way for 50–100 years.
Summary: always frame your photographs under glass or acrylic; don't worry about UV-absorbing glazing; and don't even try for an airtight frame—won't work, bad idea.
As best as we currently understand inkjet prints, if you follow these recommendations inkjet prints are likely to substantially outlast conventional darkroom prints on display.
And as with all conservation research, this is subject to change without notice, your mileage may differ, and only four out of five doctors agree.
*Footnote: I am not going to get involved in detailed discussions of preferred framing practices and materials, so please don't ask. It's way too big a subject. Just this one thing—use acid-free boards and papers but avoid the use of buffered materials**. Alkaline materials are know to be bad for all traditional color photographic prints. I don't know that they're bad for inkjet prints, but it would be what I'd assume until proven otherwise. If a museum or archival material is unbuffered, the product description will say so specifically, as buffering is more common.
**And a footnote to Ctein's footnote from Mike: buffered materials are fine, even desirable, for paper artifacts and traditional black-and-white silver gelatin ("fiber-base") prints. But Ctein is talking about color photographic prints, especially dye transfer prints.
ADDENDUM: Oren Grad just informed me that many of the Museo, Hahnemuhle and Epson fine art papers are buffered. I'd trust Epson to have some idea of what was safe to use with their inks, so belay that recommendation in my footnote to always use unbuffered boards, at least when it involves Ultrachrome inks. —Ctein
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Original contents copyright 2011 by Michael C. Johnston and/or the bylined author. All Rights Reserved.
Featured Comment by MHMG [Editor's note: "MHMG" is Mark McCormick-Goodhart, the Director of Aardenburg Imaging & Archives]: "What fascinates me with print life predictions is how often the print life figures for various products are viewed by the public as a definitive answer to the question 'How long will my print last?' The marketing guys have done a great job creating a nice soundbite for a decidedly complex issue. Indeed, two of the fundamental assumptions used to make these comparative print life predictions are rarely ever discussed. These factors are: what failure criterion has the testing lab used to decide the 'end of life' and what 'average' real-world environment has the testing lab used to extrapolate from the test conditions to actual real-world display conditions. The testing lab's chosen failure criteria may or may not square up with the individual print collector's image quality concerns, and real world light levels simply don't obey the law of averages very well. On light fading rates alone, a 'standardized' print life prediction has an error bar that easily ranges over two orders of magnitude depending on the difference between the lab's light level assumption and the real print display environment.
"OK, but a prediction based on both standardized failure criteria and normative environmental assumptions is still an apples-to-apples comparison between different products, right? Well, not necessarily in meaningful way because many print processes don't fade or discolor at a linear rate. It takes more than one measured datapoint to plot the retained image quality over time. Depending on the strictness of the chosen failure criteria, the endpoint in the test may not even detect early or mid-stage print quality deterioration. Thus, fading non linearity and visually different failure modes can cause two similarly rated products to perform in markedly different ways over the 'total life span' of the print.
"All that said, it is the end-user's responsibility to take some time to consider the matter more carefully. If we begin to ask more probing questions about the industry's print durability test methods and underlying assumptions, I believe photographers, printmakers, and print collectors will eventually get more thoughtful and comprehensive answers on print longevity."
Question from GH: "Could someone explain what buffered materials is/means? Thanks!"
Mike replies: "Buffered" means that the pH has been raised to a level higher than 7 (neutral), into the alkaline range, in order to provide a safety factor against acidifying.
Acidity is the enemy of most paper artifacts, and a neutral or near-neutral pH is the ideal environment for paper. As acidic particulates or gasses attack the print, the pH gradually lowers—that is, the environment becomes more acid and less alkaline. Buffering allows some lowering of the pH without going below 7.
[Correction: it's more complicated than this chemically; see the Comments section for greater detail. But be warned, it gets a bit deep.]
Some color materials, however, most notably dye transfer, don't like a basic (alkaline) environment, so buffered materials should not be used. Some framers think acid-free, buffered mat board should be used for everything just because it's the standard for paper artifacts including B&W silver-gelatin prints, but, as Ctein says, that is not the case for many kinds of color photographic prints.
Featured Comment by James Miller: "Your article is well-written and more accurate than most on the subject of framing and displaying images. Thank you.
"This part could be misleading, however: 'Tight framing is very dangerous...Once you've protected the print from aerosols and particulates—and simple glazing does that—you've done all you can reasonably do.' I don't think you are suggesting that it's OK to leave the back of a frame open, but it would be a mistake for anyone to come to that wrong conclusion.
"Yes, air-tight framing would be costly, unnecessary, and impractical for consumer environments, but it would not be 'dangerous' beyond giving one a false sense of security. Anyway, there is a world of difference between truly air-tight framing and the tightly-closed framing recommended by every credible preservation authority.
"The recommendations are to use glazing in the front (always), insulating filler in the back of the frame, and tight closure using a sturdy dust cover. That assembly certainly would not be air-tight, but tighter closure of the frame, front and back, better slows the rate of temperature and humidity changes inside the frame. Slowing the rate of change inside the frame minimizes expansion/contraction cycles (mechanical stress) of the art's substrate.
"Framers often confuse this tight closure recommendation with jamming the fitting points into the back as tightly as possible. That is a common mistake, and a serious one, as it would restrict normal expansion/contraction cycles, causing wrinkles in the art paper. The fitting points should be installed loosely enough that the frame contents can rattle just a little.
"99% UV-filtering glass is no longer expensive, and always recommended for preservation framing. The optically-coated glass and acrylic, which usually include a UV filter, are the expensive glazing products. And when visual acuity is important, the extra cost of that benefit may become insignificant."