Defining Archival Standards in Photography

There is a great deal of confusion among photographers and artists, and those who sell and collect art, over exactly what the term “archival” means. Labeling a photographic print archival implies that it has met or exceeded a standard.

What is the standard? Is there one standard for all photographic images: color, black/white, inkjet, and alternative process? Is there a different standard for other, non-photographic prints?

The short answer is no. The Image Permanence Institute, a department of RIT’s College of Imaging Arts & Sciences, offers this definition:

“Archival- a term often used to imply that a material will be stable over time. The term has neither a recognized standard definition nor a quantifiable method for verification.” (http://www.archivaladvisor.org/shtml/glossary.shtml)

The American National Standards Institute (ANSI) agrees:

“(Archival media is) material that can be expected to retain information forever, so that such information can be retrieved without significant loss when properly stored. However, there is no such material and it is not a term to be used in American National Standard material or system specifications.” (ANSI/AIIM TR21998, “Glossary of Document Technologies,” Association for Information and Image Management International, Silver Spring, MD.)

The long answer is that photographers (photographers are arguably more guilty of misusing archival than any other group) use the term to mean that a print has been made to the highest standards of craftsmanship. Realistically it simply means that the photographer has taken great care to make an object that will last as long as possible.

Since the term is unlikely to disappear from our collective vocabulary any time soon (archival apparently has excellent archival qualities) we will define archival as how long a print survives before there is noticeable change. Using this definition a photographic print is archival if it lasts as long as it is predicted to last.

For example, if a manufacturer publishes data predicting a life span of thirty years for a print material, and the print lasts without noticeable change for thirty years, it is an archival print. The estimate for Fuji Crystal Archive Type One Paper (used for analog and digital wet printing) ranges from 40 to 218 years depending on how it is stored and viewed. (A Review of Accelerated Test Methods for Predicting the Image Life of Digitally-Printed Photographs, Part II; Wilhelm Imaging Research; IS&T’s NIP20: 2004 International Conference on Digital Printing Technologies).

A platinum print can theoretically last as long as the paper it is printed on stays intact (as could a pure carbon pigment digital print). The Fuji Crystal and platinum print have very different predictable life span; both are archival if they meet their prediction.

How do we define noticeable change?

Here again, there are no industry standards or accepted definitions. The informal standard for noticeable change is generally considered to be 8%. The idea is that most people adapt to and will not notice the slow fade of an image (photographic or otherwise) until the change is approximately 8%. After 8% we are more likely to notice that the image has changed. Using this standard we have a definition for the archival life span of a print as the time it takes to reach an 8% fade.

There are caveats. Professionals are more likely to notice a change before 8%, and this percent of acceptable fade is only valid if the print fades uniformly. Uniform fade is problematic. The dyes and inks, including pigment inks, used to produce prints (color or grayscale) typically do not fade uniformly.

Much of the published data on inkjet print longevity is based on a 30% fade; the assumption supporting this standard is that the image has degraded but is still functional. While technically correct, the 8% fade standard is artistically more realistic.

A common sense standard for all photographic prints is the Grandma Test. Using the Grandma Test a print should be unnoticeably changed for three generations. It should not fade more than 8% over that time.

A reasonable approach to archival printing (wet darkroom or digital darkroom) should focus on the process of making a print because that is something the printmaker can control. It becomes a measure of craftsmanship. The idea is to produce a print that will not prematurely change due to anything associated with the printing process, or handling and storage of the print.

Generally, change can occur due to a number of factors including:

  • What the print is composed of. Silver halide molecules embedded in gelatin and coated on paper? Platinum metal coated on paper? Azo dyes on plastic? Pigment ink on paper?
  • How the print was made. There are two basic factors (and many secondary factors) that can affect the life span of a silver print, for example: what kind of paper is used (fiber or resin coated), and the processing routine (what kind of chemicals are used, their quality, and the knowledge and skill of the printer). If an inkjet print: what type of paper, what is the composition of the coating, and what kind of ink is used.
  • How the finished print is handled, viewed, and stored. A print framed under non-UV glass and hung in bright illumination can be expected to fade more quickly than an identical print kept in dark storage. The life of a print, regardless how well made it is, will be affected beyond the printer’s control.

Information on the lifespan of photographic media—traditional and digital—is published by a number of organizations: the ANSI, ISO (International Standards Organization), RIT’s Image Permanence Institute, Wilhelm Imaging Research, and Aardenburg Imaging and Archives, among others.

Wet Darkroom

 L. Maddox introduced the first silver gelatin printing paper in 1871. Today there are two common types of silver gelatin printing papers: fiber and resin coated (RC). Fiber papers generally consist of an internally sized acid free paper base and several top coatings. RC papers are similar but have a water resistant polyethylene coating on both sides of the paper base.

Silver gelatin emulsions are made light sensitive using two silver salts: silver bromide and silver chloride. Either, or a mixture of the two, can be used. There are three general silver gelatin emulsion types:

  • Silver Chloride. Used for slow warm toned papers suitable for contact printing. Silver Chloride is too slow for enlargements. In the past silver chloride was used for print out papers (POP) that did not require chemical development after exposure.
  • Silver Bromide. Used for fast enlarging paper that typically produces a neutral to cold print color.
  • Chlorobromide. A mixture of silver chloride and silver bromide. The most common silver gelatin enlarging papers today. The image color will vary according to the processing chemistry used.

Both fiber and RC papers are available with emulsions that are contrast graded or variable contrast.

All other factors being equal, RC papers have a shorter predictable life span compared to fiber paper. RC plastic coatings eventually break down. More importantly the cut edges of RC paper are theoretically sealed to prevent water and chemistry from seeping into the enclosed paper fiber. These edges are suspect. When using RC paper follow the processing instructions exactly. Do not allow the paper to be wet, either in a chemical solution or water, longer than required. This will minimize the potential for seepage along the RC edges.

Fiber paper does not have a resin coating. Instead, the paper base is first coated with baryta (barium hydroxide), followed by a light sensitive emulsion. The paper stock is inherently stable but chemistry, especially fixer by-products, can penetrate the paper fiber and are difficult to remove. Fiber papers take more time and care to process properly. Fiber has been the first choice among serious printers; particularly because the air-dried surface is aesthetically pleasing, and because fiber paper offers more flexibility in processing.

The most common type of print failure with fiber or RC papers isn’t fading but staining or spotting caused by chemical contamination of the emulsion and/or the paper base. Contamination can happen during the making of the print or through improper handling, viewing, and storage. The photographer’s job is to make certain that nothing they do contributes to the premature failure of the print.

To avoid contamination the following general wet darkroom guidelines must be strictly followed:

  • Work Clean. Any thing that comes into contact with the printing paper before, during, and after processing must be clean. The enlarging easel, your hands (an often overlooked and extremely important consideration), the trays, sink, print tongs and washer, the drying screens and countertops are all potential problems. To avoid contamination Start clean, Work clean, and Finish clean.
  • Use Fresh Chemistry. Stale, exhausted or contaminated chemistry is almost certain to ruin prints. All chemistry oxidizes when it comes into contact with air. Chemistry diluted with water and in open trays oxidizes more quickly than when stored in a bottle. Chemicals change and accumulated by-products as they are used. Never use chemistry beyond the exhaustion point. Work methodically, especially in a group darkroom.
  • Use Fresh Paper. Age, heat, temperature, humidity, air pollution, and radiation affect silver gelatin paper. Use fresh paper for any print that is intended to have a long life span. Keep paper fresh by refrigerating it or, when necessary, freezing it. If you do this, be certain to allow the paper to slowly reach room temperature before opening the package (to avoid condensation).

Contamination is a great concern in wet darkroom processing. It can come from anywhere at anytime, particularly in a darkroom used by more than one person. You should develop a methodical approach to cleanliness and encourage the same in all those who work in the darkroom with you.

The silver particles that compose a silver gelatin print are susceptible to oxidation (like silver jewelry). Some toning processes may improve the life span of a silver gelatin print. Gold toners, for example, offer protection by coating the silver particles in the print emulsion. Sulfide and selenium toners convert the silver particles into more stable silver sulfide and silver selenide compounds.

For many traditionally trained photographers the assumed definition of archival has been “a chemically clean silver gelatin fiber print toned in selenium”. This definition dates to the publication of the Ansel Adams manuals in the 1960’s. Current research suggests that selenium toning may not be as effective as previously thought.

Toning silver gelatin prints is often an aesthetic decision; by changing the color of a grayscale print it’s emotional message can be altered in powerful ways. Prints can also be stained, dyed, hand colored, painted, coated, or otherwise altered. The effect on the print life span is unpredictable, at best.

Digital Darkroom

There are two material reasons why an inkjet print may fail the Grandma Test: the ink used and the type of media the ink is printed on.

Inkjet printers—at least those that most photographers purchase (as compared to industrial inkjet printing)—use soluble dye or pigment ink. The composition of the ink typically includes the colorant (dye or pigment), surfactants and additives, a humectant, and about 65% water.

Dye ink has a larger gamut (color space) than pigment ink. Using dye ink a photographer can expect a deeper black and colors that appear more vivid (especially when printed on glossy papers). Unfortunately, under similar viewing and storage conditions, dye ink fades much quicker than pigment ink. Although dye ink has improved considerably over the last decade, pigment ink is required to maximize life span of a print.

Most, but not all, inkjet printers currently marketed to photographers and artists use pigment ink or offer the consumer a choice. Some ink marketed as pigment actually has a small amount of dye added to the formula. This is particularly true for black ink. Pure black pigment ink tends to print as a deep brown. It is not uncommon for a small amount of black dye to be added to black pigment to guarantee a richer black.

Today pigment ink sets typically offer two black inks. Photo Black is intended for printing on resin coated and baryta-type papers; Matt Black is for fine art matt papers. Photo Black is a mixture of dye and pigment ink.

Photographers primarily interested in printing grayscale images can remove the color ink set from a printer and substitute a set of dedicated pigment grayscale inks (the set will have a dense black and progressively lighter shades of the same ink). No OEM (original equipment manufacturer) grayscale ink sets are offered by the Big Three: Epson, Hewlett Packard, and Canon. Going completely grayscale means leaving the OEM path, requiring the photographer to learn more and use third-party software to drive the printer. The results, however, can be beautiful, and the prints—using high quality papers—can have an expected life span equal to or exceeding the best toned silver gelatin prints.

There are a staggering number of papers and other media marketed for inkjet printing but relatively few manufacturers. Many papers are sold under different brand names. Today most inkjet media fall into four general categories:

Resin-coated paper. Designed to give a similar appearance to wet darkroom RC papers (Epson Premium Glossy and Premium Luster, for example).

Fine art matt paper. Coated for inkjet, these papers mimic the watercolor and printing papers that artists and printers have used for centuries. This is a crowded category with papers ranging from utilitarian (Epson Enhanced Matte) to high quality (Hahnemuhle Photo Rag).

Baryta type paper. A recent addition to the digital darkroom, baryta papers are similar to fine art matt but are manufactured with a surface that is intended to evoke an air-dried silver gelatin print. It should be noted that baryta is actually used in the manufacturing of silver gelatin printing papers. Not so for inkjet. The reference to baryta in inkjet printing is simply a subjective description of surface appearance.

Other. This includes papers not coated for inkjet printing (from low to high quality), plastics, canvas, fabric, and anything else that can be fed through an inkjet printer. Life span information for media in this category is very minimal and speculative.

The composition of the media has a direct impact on the life span of a print. A base paper, for example, must be acid-free. It should be pH-neutral or slightly alkaline (basic pH of 7 or slightly greater). Eliminating acidity is the most important consideration in making paper with a long life span (and is equally important for materials used for short and long term storage).

“Museum Grade” 100% cotton-rag paper remains the first choice among serious printers. However, there is “Conservation Grade” alpha cellulose paper made with high-grade acid and lignin free wood pulp that perform as well.

According to the test data published by the Wilhelm Research Institute some alpha cellulose paper out performs rag. Obviously, the predictable life span of an inkjet print is affected by many variables. Regardless, properly manufactured acid free paper (properly handled and stored) can have a life span exceeding 1,000 years.

During manufacturing a paper base is usually internally sized; material (for example gelatin, an animal by-product, has been used since at least the 8th century for internally sizing paper) is added to the paper to control water resistance (and also to influence the weight and surface texture). A paper may also have a surface sizing applied to improve strength, printability, and water resistance.

Optical brightening agents (OBA’s) are common additives to surface sizing for both wet darkroom and inkjet papers. Used in laundry detergents and some cosmetics, OBA’s are dyes added to improve a paper’s opacity and the appearance of “whiteness” (they work by absorbing ultraviolet light and reflecting light in the blue region of the electromagnetic spectrum through fluorescence).

You can gain some insight into how much OBA is included in the manufacturing of an inkjet paper (but not which kind of OBA is used) by looking up the paper’s ISO Brightness number. You can test for OBA using a spectrophotometer and software (BabelColor’s Color Translator & Analyzer and some professional profiling software will work). You also may locate some information on the web.

A few examples:

Epson Enhanced Matt (ISO Brightness: 104)

w2

Hahnemuhle Photo Rag 308 gm (ISO Brightness: 92.5)

w1

Hahnemuhle Photo Rag Bright White 310 gm (ISO Brightness: 99)

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(http://www.pusztaiphoto.com/articles/printing/spectrums/webchart.aspx)

What do the ISO Brightness numbers and charts mean? Epson Enhanced Matte reflects 104% of the energy falling on its surface (it actually gains illumination from the fluorescence of the OBA’s). Hahnemuhle Photo Rag 308 reflects 92.5%, and Photo Rag Bright White reflects 99%.

We can assume that Enhanced Matte is manufactured with more OBA than either Hahnemuhle papers. And we can assume that the Photo Rag Bright white has a brighter white because it is manufactured with more OBA than the standard Photo Rag.

This information also tells us that of these three papers the Hahnemuhle Photo Rag will change less over its life span (all other factors being equal), and the other two will experience more change. Why?

OBA’s have the unfortunate characteristic of “burn out” over time (there are many types of OBA’s, varying considerably in molecular composition; some burn out quicker than others). This simply means that wet darkroom and inkjet prints on OBA paper will exhibit an inevitable shift in paper white over time (the surface will appear a bit yellow—the natural color of the paper is revealed as the OBA burns out—and a bit dull).

There is no evidence that suggests the burn out of OBA, in either a silver gelatin or inkjet print, has harmful effects (that it would contribute to a shorter life span) on prints. We can predict that the paper white will fade over time, but we cannot predict that this change will manifest other changes in the print.

Protecting inkjet prints from exposure to UV will retard OBA burn out. If silver gelatin paper (fiber or RC) is over-washed during processing, or left to stand in water excessively, some of the OBA will leach out resulting in a print that is unexpected dull when dry.

If we want to eliminate the effect of OBA burn out, we must use inkjet papers that do not contain them.

Beyond the paper base and internal and/or surface sizing, inkjet papers are coated for inkjet printing. Inkjet coatings are often composed from silica pigment, PVOH (polyvinyl alcohol) binder, and a cationic additive. They are designed to maximize color gamut and the rendering of detail, primarily by controlling dot gain (the tendency for a droplet of ink to spread when applied to a surface) and porosity (how the ink is absorbed into or through the coating).

These coatings are applied over any sizing or RC coating, and are proprietary (although like paper manufacturing most inkjet coating is produced by third-paper chemical companies).

Compared to the relatively “hard” surface of most silver gelatin papers, ink prints on all media are more likely to scratch or scuff. Care must be taken in the handling of all inkjet media from the moment it leaves the packaging to storage and viewing.

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