You may be aware that over the last 25 years, there has been a major effort to convert paper production from acidic products that deteriorate quickly to more stable paper. The movement largely came from the library community’s concerns about rapidly deteriorating paper in their collections. The result is that there are now no western producers making acidic papers anymore (other than newsprint), which is great news for libraries, archives and consumers.

Not all of these papers, however, can be guaranteed to truly last long-term (by that we mean over 300 years). Manufacturers can, and do, change the chemical composition of papers quite regularly, and as consumers and staff in a library/archive, it is good to know what is available and how to use it best.

So, let’s look at what’s around us. Our inexpensive everyday photocopy paper is not acidic when tested with a pH pen. This paper can be labeled “acid-free.”

Test of the pH on everyday photocopy paper.

But it does not meet standards for longevity that we want for paper that will be incorporated with collections on a permanent basis. It’s perfectly fine for bookmarks and flags—items used temporarily.

For long-term quality, look for papers that are marked “permanent” or “archival,” with the infinity symbol set inside a circle.

Infinity symbol designating a permanent or archival quality paper.

Permanent papers can be made with wood pulp (where the harmful acidic lignin is found), but the lignin is generally removed and no acidic additives are included during manufacture. Permanent papers are expected to last several hundred years under normal library or archival storage conditions. To be labeled “permanent” with the infinity symbol, the paper must meet either ISO 9706 or ANSI/NISO Z39.48-1992 standards.

Archival papers are made to an even higher standard and will last up to 1000 years. These papers are produced with cellulose fibres from plants other than wood and do not contain lignin (usually cotton or linen). Also, the standard for archival papers (ISO 11108) includes requirements for paper strength, which the standards for permanent papers do not include.

Papers labeled as either permanent or archival are recommended for long-term use with collections. It is probably best to choose archival papers when strength is a consideration, such as wrapping or enclosures.

An archival quality paper enclosure.

As a final note, it is important to remember that the storage environment for paper also has a huge impact on its longevity. For every five-degree reduction in temperature, it is estimated that the lifespan of paper doubles. Everybody put on a sweater!