Archiving Digital Imagery for the Long Haul—Part Four of Four
Digital Print Storage
The first three chapters of this series had to do with storing and archiving digital image files, which aside from a collection of electronic “ones,” “zeros” and whatever form of storage device they’re housed in, are intangible. You can’t pick them up in your hands, feel their surface textures, or hang them on the wall. If you want such attributes you must first print the image(s), these days most likely in the form of an inkjet print.
It Starts With Your Choice of Printer
When purchasing an inkjet printer for outputting archival-quality prints, you should pay attention to the type of ink set utilized by the printer. Even though the expected lifetime of inkjet prints—including output from the most basic of inkjet printers—has increased dramatically over the past few years, your choice of printer will determine the both the quality of the images you are printing as well as the life expectancy of your prints.
Note: The definition of “life expectancy” when used in conjunction with inkjet prints does not indicate how long it will take for the image to disappear, but how long a print will last before the first signs of fading become noticeable. The print might, in fact, last decades longer but the colors will become progressively muted over time, with some colors fading quicker than others. (Like old tattoos, the red end of the spectrum fades quicker than the blue-green end of the spectrum).
Dye, Dye Hybrid or Pigment-Based Ink Sets
There are three basic formulations for inkjet inks: dye, hybrid dye (aka dye/pigment) and pure pigment. Dye-based inks are a "good news/bad news" sort of ink set. The good news is that dye-based inks (usually) offer the widest color gamut and tonal ranges. The bad news is that dye-based inks are the least stable of the three, though compared to the earliest dye-based ink sets, which started fading within weeks and sometimes days, current dye technologies offer far greater life expectancies, with some makes and models boasting print life expectancies of up to 100 years.*
(*Read the fine print on this one.)
The caveat here is that just as the fine print on the sticker on a new car window clearly states “Your mileage may vary,” if you read the fine print on your printer’s spec page you’ll quickly note the figures claimed by printer manufacturers are based on ideal levels of light, temperature and humidity, which in the real world seldom come close to being ideal.
If maximum print life is high on your check list, you’re better off sticking to a pigment-based ink set, which has become increasingly more common among both mid and pro-level desktop printers. Early formulations of pigment-based ink sets tended to be flat and displayed various degrees of gloss differentiation, which manifests itself in the form of differing ranges of glossiness between the black pigment (dull) and color pigments (glossy). Current pigment ink sets offer a far broader color space, denser blacks, and in general rival the image quality of dye-based ink sets, albeit with a longer shelf life.
An additional benefit of pigment-based ink sets is that instead of a single black cartridge, many pigment-based ink sets use separate blacks for printing on glossy and matte paper surfaces: Glossy or Photo Black for Glossy, Luster, and Semi-gloss paper surfaces and Matte Black for Matte and Fine-art papers.
Some pigment-based ink sets also incorporate one or two "Light Black," or "Gray" ink cartridges into the mix, which enables smoother transitions between shadow and highlight areas, better shadow details, and the ability to print extremely high-quality monochrome (B&W) photographs. Several Epson printers go as far as featuring an Advanced Black & White mode that converts and optimizes color image files for monochrome output without altering the original color file.
Ink sets, even the best of them, are only as stable as the media they’re printed on. As such, you should always make sure the media you print on is not only compatible with your particular printer (and its unique ink set), but is test-certified to ensure optimal image quality and long-term archival integrity.
To complement their respective archival-quality ink sets, many companies including Epson, Canon and HP offer a broad selection of 100% Rag, pH-neutral, museum-quality glossy, semi-gloss, luster and fine-art paper surfaces in a choice of sheet sizes, rolls and in many cases, a choice of thickness. The abovementioned companies also offer one or more varieties of cotton/poly blend canvas, which are available with matte or semi-gloss coatings, depending on your preferences and/or needs.
Note: Despite claims along the lines of “instantly dry to the touch,” it’s highly recommended to allow all prints about 24 hours to dry thoroughly and “gas down” before framing or packing them away for storage. Framing a print before it has completely dried and released residual gases can possibly compromise the print’s expected lifespan, and on a lesser level, fog the inner surface of the protective glass.
Assuming your printer is designed around a premium, archival ink set, there are a half dozen variables that determine the limits—or limitations—of how long your prints will last in the long run, and they are as follows.
Choice of Media
Depending on your particular printer/ink-set combination, premium glossy, semi-gloss and luster paper surfaces are commonly rated at 40 to 70 years. All rag fine-art papers are rated anywhere from 70 to 100-plus years, and these figures are for color images. Monochrome images, which are not nearly as vulnerable to color fade, can last twice as long, in some cases 200-plus years, before noticeable fading starts to occur.
Prints, even prints displayed behind UV-blocking glass, should be kept out of direct sunlight, and protected from long, regular exposure to indirect daylight. Equally dangerous are fluorescent lighting fixtures, which like direct sunlight contain high levels of image-destroying UV radiation. Whenever possible, illuminate display areas with indirect tungsten lights, and try to limit print exposure to spotlights.
Humidity levels should be kept comfortably low, but not desert-like. Basically, if you’re comfortable, i.e. not schvitzing, your prints are probably equally comfortable. And again, too dry can be as bad as too damp.
Like humidity levels, temperature levels should be equally low—in fact, the cooler the better. If your thermostat is set in the range of 68 to 70 degrees, you and your prints should be happy campers.
If you live in or around an urban environment and tend to leave your windows open, be aware that along with the fresh air blowing through the window are any number of airborne contaminants, which in high enough doses can compromise the safety of your prints. Ozone, an element that’s commonly high during heat spells in city environs, can be particularly damaging to print surfaces. Basically, if the weather forecast advises elderly and infirm people to stay indoors with the air conditioning running, take heed.
The materials in which you store your prints are as important as the inks and papers you choose. Sleeves, envelopes, boxes and cabinets should be manufactured by companies known for archival storage solutions. Anything made out of plastic, including foam inserts, should be certified as being inert, pH neutral, acid free and gas free, otherwise you risk undoing all of the efforts you’ve taken up to this point.
One Final Note
With the exception of the ink set/print media portion of the above text, the archiving recommendations offered in this post hold equally true for long-term storage and display parameters of conventional silver-based and color photographic prints.