What's in a Case? | The Art Institute of Chicago (original) (raw)
Walk through many of the Art Institute’s galleries, and you’ll find large cases displaying three-dimensional objects. But art isn’t all they contain—and the secrets they hold may surprise you.
In addition to serving as a physical barrier between the object and the outside world, cases allow us to control an artwork’s immediate surroundings in ways that are often imperceptible to visitors. While the overall environment of our galleries is carefully managed and monitored, many objects can benefit from the extra protections and refinements a display case offers. As a curator in Arts of the Ancient Mediterranean and Byzantium, I care for some of the oldest artworks in our collection, and these cases play an important role in our strategy for ensuring their long-term preservation. The safest environment for any given work is often determined by the materials it’s made from. Gold, for example, is among the most stable materials used by ancient makers, but other metals, like bronze and copper, are susceptible to corrosion, which can be initiated or accelerated by changes in relative humidity. Organic materials like wood, meanwhile, can be damaged by expansion and contraction when relative humidity fluctuates, while textiles and painted objects are sensitive to light and can fade with prolonged exposure.
Museum cases—designed and engineered by only a few companies worldwide—offer a high degree of sophistication and specialization that allows us to monitor and control these forces of change, minimizing any potential for damage or wear to a particular object while it’s on display.
But how, exactly, do they do it? Let’s look inside and see.
Opening the access panel at the base is always step number one. But to reach the art, we need to raise the vitrine—the glass top of the case. While some vitrines are made from plexiglass and are light enough to be moved by hand, others are made from glass and can weigh hundreds of pounds. This particular vitrine is quite heavy, so the case contains a mechanical scissor lift. This sturdy lift provides a measure of safety for the art below as the glass is raised.
When not in use, the lift sits folded against the sides of the case. Inside the white box nearby is a mechanism used to limit how high the vitrine can be raised—a particularly important feature when you’re working in a building like ours, with a variety of ceiling heights and types of light fixtures.As you can see in the video below, the scissor lift works to slowly—and safely—lift the heavy glass vitrine.
The glass vitrine is mechanically raised with the help of a scissor lift hidden within the base.
Once the vitrine has been raised to the desired level, we’re able to tend to the artworks inside, whether to inspect them more closely, remove them for conservation work, or simply adjust their position.
Lorien tends a Greek stamnos (mixing jar) attributed to the Chicago Painter and made around 450 BCE.
Gift of Philip D. Armour and Charles L. Hutchinson
One of the most common tools we use to monitor the environment within a case is a hygrothermograph, a small meter that measures temperature and relative humidity, or RH, levels. Curatorial and Conservation and Science staff check these meters often to ensure that the microclimate inside every case is ideal and stable.
A hygrothermograph monitors the humidity level and temperature within a case.
If lower RH is needed—say, for metal objects at higher risk of corrosion—large bags of silica gel, the same material you find inside tiny packets within shoe boxes and other commercial products, is added to a sealed chamber attached to the display area. There it can work passively, simply absorbing the moisture in the air, or actively, with the addition of a fan to move the air around and through the chamber.
Large bags of silica are used to reduce relative humidity levels.
Air movement helps ensure a consistent temperature throughout the case, preventing warm air from accumulating at the top and cold air at the bottom. Some fans have special controls that allow them to automatically turn on and off throughout the day or run only when the museum is closed. This helps us keep the noise in the galleries to a minimum and conserve energy.
This control panel allows staff to regulate a case’s fan.
Balancing the amount of light needed for visitors to fully appreciate the beauty of these precious objects with the potential risk of light damage to their delicate surfaces and pigments can be a challenge. Some cases have a special light reader like this one affixed to their surface to allow for close monitoring of the light exposure an object receives.
Light readers monitor how much light an object receives.
Even the glass used to make each vitrine is carefully considered. Applied coatings provide light filtration and enhanced breakage protection. And gaskets surrounding the vitrine’s bottom edge allow for an airtight seal when the case is fully closed, helping to maintain the perfect internal environment despite any changes in temperature, light, or humidity that may occur within a gallery. These gaskets also ensure that dust and dirt can’t get inside and onto the objects.
In short, there’s a lot going on inside a case that visitors don’t see, and that’s entirely by design. These myriad features and monitoring tools are meant to function unnoticed, so nothing gets between you and the art—except, of course, for a layer of glass.
—Lorien Yonker, assistant curator, Arts of the Ancient Mediterranean and Byzantium