The ABC's of ISO

It is a part of IPI’s mission to disseminate the results of our research to the field of cultural heritage preservation. We do this through a variety of avenues including presentations at conferences and publications in journals. A third way we reach our audience is through participating in the development of ISO (International Organization for Standardization) standards. Many IPI researchers have participated on ISO committees related to the permanence of imaging materials. Currently, IPI veteran, Dr. Peter Adelstein chairs the ISO working group charged with creating all of the standards on the physical properties and permanence of imaging materials. He has been representing IPI in this position since IPI’s inception in 1985. Before coming to IPI, Dr. Adelstein represented the Eastman Kodak Company on the committee as far back as 1973. In the following interview, Dr. Adelstein explains the standards writing process, the history of permanence related standards, and the future of standards for digital print materials.

What is an international standard?

An international standard is a document prepared by ISO which is headquartered in Geneva, Switzerland. They publish the most authoritative and widely recognized standards in the field of imaging. These documents are all designated first by the letters ISO. The first three numbers 189 indicate that the standard is in the area of physical and permanence properties. The last two numbers designate the topic. For example, the standard on storage conditions for refection prints is ISO 18920.

How is ISO organized?

The ISO organization is divided into multiple technical committees. The permanence standards are written by technical committee TC42 Imaging. Membership in this technical committee is restricted to ISO member countries. In other words, members can only participate through their own national standards organization, not as individual contributors. For example, experts from the USA contribute through the American National Standards Institute (ANSI), experts from the United Kingdom through the British Standards Institute (BSI), and so on. A dozen countries are members of TC42.

Have TC42 standards been in existence for a long time?

The TC42 committee dates back to 1955 when the first meeting was held in Stockholm, Sweden. There have been many changes since then, both in the participating countries and in the topics covered. During the first few decades, most of the delegates came from Western Europe and the United States; however, as time passed, countries from Asia joined. The areas of interest have also changed radically. Initially, there was considerable activity on the preservation of black-and-white silver microfilm. This was a prime concern in the photographic field. The first permanence standard issued featured both a specification for this film and recommended storage conditions. This document actually covered both topics. It was subsequently withdrawn and separate standards were written for each subject. This was a logical division since the standard was directed at two different groups. The film specifications were important to the manufacturers while the storage conditions were of prime interest to the users. This set the pattern for the future standards with separate documents for vocabulary, specifications, storage conditions, and test methods. As the critical interests in photographic permanence changed, so did the published standards. Documents were subsequently published on physical test procedures, image testing of color, recommended storage conditions, and electronic media. Most recently the emphasis has been on the permanence of digital prints.

How are standards prepared?

ISO standards are prepared in a very structured environment. This is essential in order to obtain the best consensus from the many countries and participants involved. One of the reasons that ISO standards are well regarded is due to the many levels of ballots that are required. Initially a subgroup of technical experts, headed by a project leader, prepares the first draft which is then circulated to this subgroup as a working draft. There can be many versions of a working draft in order to reach consensus. After agreement is reached, the working draft is then balloted to the participating countries in TC42 as a committee draft, each country being allowed a single vote. Again there may be several versions in order to resolve differences. The next balloting stage is a draft international standard which goes to all the countries in ISO. Then there is a final ballot which is only to verify that all the balloting requirements and resulting comments have followed standardized procedures. This procedure is time consuming and laborious, but this elaborate process ensures that a published document represents the best thinking available and that all concerns are considered. It also guards against any organization using an ISO standard for marketing purposes. This is the reason why ISO standards are widely recognized, but the downside is that it may take a long time before a document is finalized.

Do standard developers meet in person?

Yes they do. The TC42 group involved with permanence and physical properties meet twice a year. Usually between 40 and 50 experts attend. The meetings rotate between the United States, Europe and Japan. These face-to-face meetings are very helpful in rectifying technical differences as well as encouraging co-operation by establishing rapport. Between meetings, the various ballots are distributed by email. While email facilitates the balloting procedure and is less time consuming than regular mail, it is still not a speedy process. ISO requires sufficient time periods between the distribution of a ballot and the deadline when voting is closed.

Are standards written only based on existing knowledge?

Existing knowledge on the behavior of imaging materials over long time periods provides practical experience which helps validate recommended storage conditions. This information is augmented by laboratory tests which predict long-term aging behavior by subjecting the materials to elevated temperatures and calculating behavior under practical conditions. However, this is not the case for standards on test methods. It is absolutely essential that these test methods be reproducible and that different laboratories obtain similar results. This frequently requires what is referred to as round robin testing (several labs performing the same test on the same materials to establish reproducibility). This is very time consuming since samples must be prepared, distributed to the laboratories, experiments performed following the proposed test procedure, and the results sent to a single participant for analysis. If there are significant differences in the results, the cause must be determined and corrections made in the test method. Sometimes additional round robin testing must be performed. There have been many examples when round robin testing has advanced the state of our knowledge. For example, a number of years ago, a round robin on light fade testing showed vast differences between laboratories. It was subsequently found that some of these differences were due to uncontrolled pollution levels in the testing environment. This had a very marked effect on some digital prints and was a variable which had to be controlled.

Why are ISO standards so well regarded?

It is basically because of the extensive review process just described. Many factors are critical to the preservation of imaging materials and frequently there is no unanimity of opinion as to their relative importance. Such differences frequently arise from the varied backgrounds of those involved in the field. For example, the manufacturer is concerned with the behavior of a specific material, the scientist will tend to stress factors which contribute to the importance of a test, the archivist will focus on storage conditions which can be managed in practice, while the administrator is sensitive to the costs involved. Another source of differences is the prevailing environment in different countries. For example, the normal humidity in one country can be very different from that in another and this influences the recommendation for practical storage conditions. A key purpose of standards is to resolve such differences and to arrive at a consensus which is technically sound, practical, and which will provide maximum utility. However, users should understand that ISO standards are a consensus and they frequently involve compromises.

What are the types of standards on physical properties and permanence?

Standards can be divided into five major types. These are (1) material specifications, (2) test methods on physical properties, (3) test methods on imaging properties, (4) storage and handling recommendations, and (5) a glossary. There are currently 37 published documents and nine standards under development related to physical properties and image permanence. A listing of these standards is available here.

Who are these standards intended for?

It depends on the particular standard. Those on storage and handling are intended for collecting institutions such as museums, archives, and libraries. Those on test methods are usually intended for manufacturers. Materials specifications will be of use to both manufacturers and purchasing agents.

Has IPI played a major role in standards development?

Definitely. Even before IPI was founded in 1985, several future IPI staff were involved in both ISO leadership and as initiators and developers of specific standards including many of the tests methods for physical properties and image stability. This activity has then continued through the entire twenty-five years of IPI’s existence. IPI has contributed significantly to a variety of standards including those on enclosures (18902), chemical conversion of silver images (18915), the photographic activity test (18916), magnetic tape storage (18923), handling of magnetic tapes (18933), and storage of multiple media types (18934).

Is ISO currently involved with digital print permanence?

The permanence of digital prints is the main focus of work these days. It is well recognized that the future source of photographic prints are those produced digitally. This involves the technologies of ink jet, dye sublimation and electrophotography. Specifically, work has concentrated on test methods, which involve the stability of digital images due to heat, pollution, humidity and light. Test method documents for the first three of these stresses are in the advanced stage of completion. When all test methods have been finalized, work will commence on preparing a digital print specification. IPI’s recent research on digital print stability is contributing significantly to these efforts.

How can I participate in the development of ISO standards on the permanence and preservation of traditional and modern imaging materials?

Technical Committee TC42 welcomes and encourages participation in the writing of ISO standards on permanence and preservation. The committee recognizes that ISO standards can only reflect the knowledge and expertise of those who contribute to and use these documents. Having input from preservationists and conservators is critical as they represent the user community and their involvement is encouraged. Information on becoming a participating contributor can be obtained from Susanne Grinnan ( who is the administrator for IS&T, the sponsoring organization.

They may be purchased from two sources:

Current Standards on the Physical Properties and Permanence of Imaging Materials Related to Digital Prints

Material Specifications

    • 18902 Specification for Albums, Framing and Storage Materials
    • 18916 Photographic Activity Test for Enclosure Materials
    • 18932 Specification for Adhesive Mounting Systems
    • 18940 Specifications for Permanence of Digital Color Prints - Under development
    • 18948 Specifications for Permanence of Photobooks - Under development

Test Methods – Physical Properties

    • 18903 Determination of Dimensional Change of Film and Paper
    • 18907 Wedge Brittleness Test for Photographic Films and Paper
    • 18910 Determination of Curl of Photographic Film and Paper
    • 18935 Determination of Indoor Water Resistance of Printed Color Images
    • 18947 Determinations of Abrasion, Scuff and Smudge Resistance of Color Images - Under development

Test Methods – Image Stability

    • 18909 Method for Measuring Image Stability of Processed Photographic Color Films and Paper Prints
    • 18930 Evaluating Image Stability of Color Reflection Prints under Outdoor Conditions
    • 18936 Method for Measuring Thermal Stability of Processed Color Photographs - Under development
    • 18937 Methods for Measuring Indoor Light Stability of Processed Color Photographs - Under development
    • 18939 Methods for Measuring Permanence of Digital Hard Copy for Medical Imaging 18941 Method for Measuring Stability for Ozone Gas Fading of Processed Color Photographs - Under development
    • 18944 Test Print Construction and Measurement of Color Photographic Prints - Under development
    • 18946 Methods for Testing Humidity Fastness of Color Photographic Prints - Under development

Storage and Handling Recommendations

    • 18920 Storage of Processed Photographic Reflection Prints
    • 18934 Storage Environments for Multiple Media Archives


    • 18913 Vocabulary on Permanence


(Note: This interview was adapted from a previous article but with a new focus on standards for digital prints.)