Eye on the Esplanade: Protecting treasures from the dangers of light

By Medicine Hat News on May 4, 2018.

We in the museum at the Esplanade Arts and Heritage Centre are often called by people looking for advice on how to preserve their own treasures. Whether it’s a family wedding dress, an heirloom quilt, or the painted wooden chest great-granddad brought “from the old country,” one piece of advice is almost always the same — keep it out of the light.

If you have ever taken an old photograph out of a frame that it’s been in for a long time, you’re likely familiar with the damaging effects of light. The edges of the photo that were protected by the frame itself are nice and white, while the image that was displayed through glass may be faded and yellowed. The paper of the photograph itself may even be brittle. Discolouration and structural weakness are both sure signs that light has been at work.

The damage caused by light is both cumulative and irreversible. The more an object is exposed to light, the more damage it will sustain —and even resting in total darkness will not undo any of the damage. Light exposure may be high-intensity and short term, or it may be low-level over a long span — the damage will be the same.

Not all light is created equal. The sunglasses industry has done a good job of getting the word out that ultraviolet (UV) light is particularly bad. Sunlight and fluorescent light bulbs are both high emitters of UV radiation. Most UV from light sources can be removed by filters (that’s what good sunglasses do) — but that doesn’t remove the damage caused by visible light. If there’s enough light on an object for you to see it, light is damaging it. The damage might be so minimal that you won’t notice it in your lifetime — but in the museum world, we’re committed to preserving objects for many lifetimes beyond our own.

At the Esplanade, we take limiting light damage seriously. We shut out harmful sunlight by allowing no windows in our artifact storage, work or gallery spaces. All our fluorescent light bulbs are individually filtered to reduce 99 per cent of UV radiation, and we change the filters well before their end-of-life date. Our storage space is kept dark except when someone is working in there — and then we have sectional lighting, so only the area that needs the light gets it. Our most light-sensitive pieces are stored in lidded boxes; even if the light is on, it doesn’t fall on these artifacts. We carefully monitor light levels in our galleries to ensure we don’t exceed recommended amounts for our exhibitions.

A few inorganic materials — stone, unpainted metals, most glass, etc. — aren’t bothered by light. For anything else, long-term preservation is greatly enhanced by limiting the light it receives.

Tim McShane is Museum Curatorial assistant.

8
-7