The eternal dilemma for all museums revolves around light: we need light to see our collections, but light causes damage that eventually leads to objects’ destruction. Mitigating light exposure can help extend the lifespan of objects on display and is incredibly important to the longevity of the collection. Numerous publications have been written about the damage caused by light and to set guidelines for the quantity of light museum objects should receive. Monitoring light in an historic house museum such as Winterthur creates some interesting challenges. First, the house is enormous. It has 9 floors, 175 rooms, and more than 400 windows; that is a lot of space and means for light to enter the collection.
Second, the rooms are located both above and below ground level. This means that both daylight and artificial light have an impact on the rooms. Additionally, the rooms vary in shape and size, meaning light will impact them all in different ways depending on the direction they face, the number of windows they have, and how the lighting system is set. Lastly, the majority of the Winterthur collection is permanently displayed. Other institutions display a very small portion of their collection, rotating out objects to allow them to “rest” in darker storage areas to give them a break from exhibition lighting. Winterthur aims to present the rooms as they were when Henry Francis du Pont designed them, leaving very little room for the rotation of objects.
So how does the Conservation Preventive Team monitor light, and how do we know what those numbers mean? Strategically placed throughout the museum are digital loggers that electronically track light exposure. The data is downloaded every few weeks, processed, and compared to the guidelines for different material sensitivities. We then use those totals to make recommendations for how to better improve lighting conditions within the museum to help protect our valuable collection.Most recently, Winterthur conducted a four-year study of light in the collection, beginning in 2012 before the installation of the new storm windows and continuing through August 2016, a full year after the new windows had been installed. One of my major projects was to analyze the data and assess the impact of the window replacement.
Replacing the storm windows had a significant impact on the light levels within the collection. As you can see in the image above, high peaks of light have been reduced by almost 90% of what they were prior to the installation. Less light coming in means less damage to the objects and allows our collection to continue to be on view for visitors to enjoy. We’ll continue to collect data and monitor more spaces throughout the collection to ensure we are creating an environment that is safe for our objects. To learn more about preventative conservation, meet members of the preventative team, and gain practical advice for the objects you own at home, consider signing up for the Conservation Clinic, now features a collections care table.
Post by Liz Peirce, 2015–16 Samuel H. Kress Fellow in Conservation at Winterthur