Standards 101

The published standards on the permanence of imaging materials can be very confusing, especially to those who have not been involved with their preparation. However, they can be extremely important to those who are active in this field. This page is intended to provide basic information about international standards, particularly on their usefulness, preparation, and limitations. Questions and answers are given on specific aspects of these topics.

What is an International Standard?

An international standard on image permanence is a document prepared by the International Organization for Standardization, which is headquartered in Geneva, Switzerland. They publish the most authoritative and world recognized standards in the field of photography. These documents are all designated by the letters ISO. In the field of physical and permanence properties of imaging materials, they are easily recognized by the numerical identification ISO 189xx.

How is ISO Organized?

The ISO organization is divided into technical committees. This presentation is concerned with standards written by technical committee TC 42 on photography. Membership in a technical committee is restricted to member countries. In other words, individual 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 TC 42.

Have TC 42 standards been in existence a long time?

They date 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.

The changes in the countries reflect the changes in their manufacturing facilities. During the first few decades, most of the delegates came from Western Europe and the United States. However, in recent decades there has been active participation from Japan.

The areas of interest have also changed radically. Initially, there was considerable activity concerned with 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 It was subsequently withdrawn and separate standards have been since written on each subject. This set the precedence for the future standards with separate documents for 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, with 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.

The important point to emphasize is that there are multiple ballots. This procedure is time consuming and laborious but this elaborate process insures that a published document represents the best thinking available and that all concerns are considered. It also guards against any organization or country 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 explaining technical differences as well as helping 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 that regular mail, it is still not a speedy process. ISO requires sufficient time periods between the distribution of a ballot and the deadline when it is closed.

Are standards written only based on existing knowledge?

Existing knowledge is the basis for preparing documents on recommended storage and handling practices. This is because long time periods are of interest and these standards can only be based on practical experience. However, this is not so for standards on test methods. It is absolutely essential that test methods are reproducible in different laboratories, and can obtain similar results. This frequently requires round robin testing. This is very time consuming since samples must be prepared and distributed to the laboratories. Tests must be performed following the proposed procedure and the results must be sent to a single participant for analysis. If there are significant differences in the results, the cause must be determined and corrections must be made in the test method. Sometimes additional round robin testing needs to 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 exposure 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 can influence the recommendation for practical storage conditions.

A key purpose of standards is to resolve such differences and to arrive at a consensus that is technically sound, practical, and provides 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 a (5) glossary. There are currently 37 published documents and nine standards under development. A listing of these standards is available here.

Who are these standards intended for?

It depends on the particular standard. Standards on storage and handling are intended for consumers such as archivists and librarians; while standards on test methods are for manufacturers. Specifications are useful to both manufacturers and purchasing agents.

Has IPI played a major role in standards development?

Definitely. Before IPI was founded in 1985, several individuals were involved in both a leadership position and also as initiators and developers of specific standards. The latter include many of the tests for physical properties and image stability. This activity has continued during the past twenty-five years of IPIs existence, assuming both a leadership role and as project leaders of specific documents. Among the latter are the specification for 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 (18934).

Is ISO currently involved with digital print permanence?

The permanence of these prints is the main focus of work these days. It is well recognized that the future source of imaging prints are those produced digitally. This involves the technologies of inkjet, thermal dye sublimation and electrophotography. Specifically, work has concentrated on test methods, which involve the stability of digital images due to aging, pollution, humidity and light. Test method documents are in the advanced stage of completion on the first three of these external stresses. When all test methods have been finalized, work will commence on preparing a digital print specification.

How do I obtain copies of ISO standards?

They may be purchased from two sources: