This is a guest post written by Dr. Eric Monroe, Head of the Scientific Laboratory Section of the Preservation Research and Testing Division. One of his research interests involves examining the impact and consequences of volatile compounds and odors in the Library.
The presence of odors throughout the Library of Congress is hardly a surprise to anyone. Many people find the smell of ‘old books’ is both distinctive and familiar, but the extent of odors at the Library can extend far beyond those from our paper collections. Odors are caused by the presence of volatile organic compounds (VOCs) in the air. Often, these compounds are thought of as being innocuous or as a health and safety concern. However, these compounds can also present risks to the long term preservation of the collections, even when they pose no health risk to people.
In the Library, VOCs can emit from almost everywhere including from aging collections, visitors (clothing, perfume, personal care products, etc.), the outside environment, as well as materials used in the construction of storage areas, housing materials for collection items, and exhibition cases. We will save discussion of the compounds coming directly from collections for a later blog and focus here on how we look at the materials in spaces that are close to collections, and how they may present a risk to collections.
One test method that is broadly used in museums and libraries to detect the presence of harmful emissions is the Oddy test. This test was developed in the 1970s and involves exposing test metals (typically lead, silver, and copper) to volatile compounds from a test material within a sealed jar under elevated temperature and humidity. After 28 days of exposure, the metals are examined for signs of corrosion, tarnishing, and/or deposition. While broadly used, this test presents certain limitations in regard to reproducibility, interpretation, and required test duration. Additionally, we can’t identify the ‘bad actor’ and it takes a month to get results. That’s a long time when we don’t want to cause harm to our collections.
While PRTD still regularly performs Oddy tests on materials proposed for storage space and exhibition construction, we have been exploring the use of a methodology faster and more accurate for the last several years. We have adapted a testing method typically used in the automotive industry to examine the off gassing of materials used in the cabin of automobiles and identify not only what compounds are coming off of the plastics, fabrics, etc. in the car but also how much of each compound will be emitted from the material. (It turns out that new car smell is not necessarily good for drivers and manufacturers are particularly keen to reduce the deposition of films on the inside of the windshield and windows.)