Conservation Lighting

Why do we care about light levels?

All light, but especially ultraviolet light in particular, can catalyze and/or accelerate chemical reactions that cause materials to degrade. 

Some of the most noticeable effects of exposure to light are fading of colorants and yellowing of cellulosic materials. 

To the left is a detail of the interior of a dollhouse. Areas of the textile wall hanging that were covered by pictures provide a contrast to the significantly faded textile directly exposed to interior fluorescent lighting. 

Light damage is cumulative, meaning that the greater exposure overtime the greater the damage. Check out this visual prediction tool for light damage from CCI. 


Duncan Monro and Electra Havemeyer Webb, Ramshackle Inn Doll's House, unknown date. Wood, pigment, metal, glass, textile, paper,leather, ceramic and plastic, 37 ½ x 31 5/16 x 16 3/8 in. Collection of ShelburneMuseum, gift of Zasu Pitts. 30.1-5.

Photo taken by Rick Kerschner, courtesy of Shelburne Museum


 

Balancing visibility and preservation

Light is also important to the viewer experience or all museums would be dark boxes. 

Filters can be used in various ways to reduce the more harmful wavelengths of light while allowing enough ambient light for viewing. 

These filters can be films applied to windows or screens placed over interior lighting. 


This image shows dimmer light levels that occurred as a result of years of use of the light bars in the dollhouse on view at Shelburne Museum. 

Unknown maker, English Gothic House, unknown. Wood,metal, glass, paper, fiber, ivory and pigment, 55 ¾ x 60 in. Collection ofShelburne Museum. 30.1-2.

Reinstallation of new light bars allows for better viewing. The light levels were measured after installation to check that they were within a safe range for the most vulnerable materials on display. 

Unknown maker, English Gothic House, unknown. Wood,metal, glass, paper, fiber, ivory and pigment, 55 ¾ x 60 in. Collection ofShelburne Museum. 30.1-2.

 

The types of interior lights used can also reduce the impact on objects. LED (light emitting diodes) have become popular in museums and galleries because they do not give off heat like incandescent bulbs and they emit very little UV light unlike fluorescent bulbs, which are based on the generation of UV energy. LEDs are now available in various color temperatures that closely simulate the daylight spectrum. LEDs can be more of an initial investment, but they last longer than incandescent and fluorescent bulbs making them a sustainable resource. 

Example of a linear array LIA

 Nichia LED light bar from Prolume, 

3000K color temp, 1/2" pitch

8' lead of 20 gage wire.

 

Lighting specifications cannot be considered in insolation. The impact of the installation has to be weighed against the potential benefit of changing the lighting source. Especially in historic interiors, the structure may not be able to receive the hardware and housing for new light fixtures. 

With this dollhouse the light bars could be attached to undecorated ceilings using existing holes. All of the furnishings had to be removed from each room during installation. 


Unknown maker, English Gothic House, unknown. Wood,metal, glass, paper, fiber, ivory and pigment, 55 ¾ x 60 in. Collection ofShelburne Museum. 30.1-2.

 

Measurements were checked multiple times to insure adequate spacing of the light bars and fit within the space. 

Diagram of measurements taken before installation. 

Workspace during installation

I am grateful to Rick Gage, Rick Kerschner, and Nancie Ravenel at Shelburne Museum for sharing their expertise on electrical systems and use of LEDs in the museum environment. 

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