Saira Haqqi, Conservation Center, Institute of Fine Arts, NYU: Let there be (less) light! A comparison of the radiation-blocking properties of selected window films

It is well known that visible light and ultraviolet radiation damage cultural heritage materials, especially those incorporating organic colorants, such as manuscript pages. While reducing the amount of visible light can negatively interfere with the viewing experience, ultraviolet radiation is not detectable by the human eye. Its removal, therefore, can only be considered beneficial. Within an exhibition setting, daylight tends to be the typical source of ultraviolet radiation. Since many collectinginstitutions are in historic buildings or are otherwise unable to eliminate unwanted ultraviolet radiation, it is common for them to install transparent ultraviolet-filtering window films.

There is a range of radiation-filtering films on the market. Most are not designed specifically with cultural heritage collections in mind. As such, several past studies have determined the extent to which various window films do block ultraviolet radiation and by extension protect light-sensitive materials. It is important to keep in mind, however, that these films do not just remove ultraviolet radiation, but may also reduce the amount of visible light entering the galleries.

This research examines a number of ultraviolet-filtering window films, in order to determine the extent to which they reduce both ultraviolet radiation and visible light, and to characterize the radiation that passes through them. It compares three different methods of evaluating window films (an ELSEC 764 environmental monitor, an OceanOptics USB2000+ spectrophotometer, and a Konica Minolta Color Meter II) and explains the differences between each assessment option. Since window films are designed for a variety of purposes, it is important to understand which method best measures specific film attributes. The data thus gathered allows cultural institutions to make informed decisions about which ultraviolet-blocking window film best reves their needs.