Preservation Tip: Light Damage
Posted On: 07/21/2017 - 2:33pm, Posted By: Scott Gampfer, Associate Vice President for Collections & Preservation
Light is one of the most common and preventable problems that can cause permanent harm to a collection. Museums and libraries guard against the effects of light in their storage, exhibition, and work spaces to protect their collections. It is also a threat to the historic documents, photographs, artwork, and objects that you may have in your home and wish to preserve.
Buckram book cover showing the effects of light damage. The spine, which was exposed to light, has faded and changed color. The front and back covers were protected from light by adjacent volumes on the shelf.
All light is harmful, but the biggest threat to collections comes from light in the ultraviolet (UV) spectrum which commonly comes from direct or reflected sunlight or from fluorescent lighting. It is important to understand that although UV radiation may be the most destructive, visible light is damaging as well and needs to be controlled for long-term preservation.
Light energy effects the chemical composition and physical structure of an object. Light damage is cumulative and irreversible. Unfortunately, damage to an object is often not realized until the appearance of the object has changed noticeably. That change can be in the form of fading, shifting of colors, and breakdown of fibers in textiles and paper.
The degree of damage caused by light depends on many factors including the intensity of the light, the duration of exposure, and the sensitivity of the object absorbing the light. Many things that we try to preserve are sensitive to light including paper, inks, dyes, pigments, textiles, leather goods, and photographs.
Light exposure to documents and objects is usually just one factor effecting the overall condition of an item. Atmospheric pollutants, temperature, relative humidity, micro-organisms, improper storage and handling, insects, inherent properties of the constituent materials, and other factors may also have had an effect on condition.
Badly faded 1866 land transfer document. The iron gall handwriting ink has faded making the document extremely difficult to read.
So, given that light energy is harmful to the things we want to preserve, what are some things we can do to protect our valuables?
- Make sure that original materials are not subjected to any sunlight where they are stored or displayed. Display sensitive items on interior walls, not subject to sunlight during the day.
- With particularly valuable or sensitive documents or photographs, consider displaying a digital scan or other copy of the item and keep the original in storage.
- If something has to be stored or displayed in an area with fluorescent lighting, install UV shields on the fluorescent tubes or other UV filtering material on fixtures. Also, items can be framed with UV filtering glazing to provide some protection.
- Boxes are a good way to protect valuable items from light damage. There are a wide variety of boxes designed specifically for long-term archival storage of objects, documents, and photographs, and constructed of safe materials. These are available from a variety of reliable sources. Storing those boxed items in cabinets further protects them from harm.
- Be sure to store your valuable documents, photographs, and objects in the part of your house that has the most stable conditions. Avoid attics, basements, garages, and other spaces where there is little environmental control.
- For those things you wish to exhibit, limit the amount of light and the length of time they are on display.
- Periodically inspect the items on display. Remember, light damage is cumulative and not reversible. By the time you see a change, damage has already been done.