Let There Be (Less) Light! A Comparison of the Radiation-blocking Properties of Selected Window Films

By Saira Haqqi (Conservation Center, NYU) and Steven Weintraub (Art Preservation Services)


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. Since daylight has a high ultraviolet content, it is essential to filter out the ultraviolet (UV) component within an exhibition setting.

There is a wide range of window treatment options with UV filtering properties on the market, including special types of window glass and window films. Most are not designed specifically with cultural heritage collections in mind. Since these window treatments do not just remove UV radiation, but also might reduce the amount of visible light entering the galleries and alter the visible spectrum of daylight, it is important to understand the full consequences of such solutions.

This research examines a number of UV-filtering window films, in order to determine the extent to which they reduce both UV radiation and visible light, and to characterize how the spectrum is modified as light 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. The experimental results will be compared to data supplied by the manufacturers.

Experimental set-up

Image: Experimental set-up

Since window films are designed for a variety of purposes, it is important to understand how to characterize their features and which method best measures specific film attributes. The data thus gathered allows cultural institutions to make informed decisions about which UV-blocking window film best serves their needs.

This paper grew out of research conducted as part of the Preventive Conservation course at the Conservation Center of the Institute of Fine Arts at New York University (NYU). It was sponsored by NYU, the National Endowment for the Humanities, and the Andrew W. Mellon Foundation and received further support from the Foundation of the American Institute for Conservation (FAIC). It was presented as a poster at the seminar on the Care and Conservation of Manuscripts in Copenhagen and at the Annual Meeting of the American Institute for Conservation in Spring, 2016.

Download the poster here.


Marbled Paper

Copyright Saira Haqqi and Steven Weibtraub, 2016.