Preservation Environment for Photographs

 Photography has undergone many changes in format and process through the years.  Each new process was developed to make photography more manageable and higher quality.  Of course for early photographs, photographers were not as concerned with how durable these paper photographs were and did not consider how they would need special care in order to be preserved for posterity.  That’s why it’s important for archivists today to understand how to care for these fragile photographs and keep them in the best condition possible.  A major part of this is knowing what the best environmental conditions are for storing archival photographs.  The environment that photographs are stored in plays a large part in influencing whether they will last over time. 

When designing or renovating a collection storage space, an archivist needs to be aware of the specific deterioration threats that could harm the collection. Deterioration occurs through three basic processes: chemical, biological, and mechanical (physical) damage. Chemical deterioration comes from chemical reactions that occur in response to heat energy and moisture. These reactions basically happen because of temperature and relative humidity (RH). These factors can cause discoloration, embrittlement, and fading. Biological decay is caused by living organisms such as mold or insects. RH is a major factor in this because these organisms thrive under high humidity conditions. Mechanical damage mostly affects hygroscopic organic materials, which are those that absorb large amounts of moisture easily. Again, RH is an important factor in this because it affects the moisture content of collections. When moisture is too low objects shrink and become brittle. If moisture is too high they swell and soften. This can lead to cracks, tears, and delamination of materials. All of these threats are important concerns, especially for photograph collections (Image Permanence Institute). 

Once an archivist knows the nature of their collection and what the possible threats will be, they can focus on how to prepare the collection environment to combat these issues. The critical issue to prepare for is how to control the temperature and RH of the collection. As mentioned above, these two factors contribute the most to long term damage of materials if they are not controlled properly. There is a variety of climate control equipment to help manage these conditions depending on an archive’s resources. If they have a decent amount of funding they may be able to install a central system that is able to filter, cool, heat, humidify, and dehumidify the air. But this is not always possible for a small archive and in that case they may have to just acquire a room air conditioner and dehumidifier/humidifier. These may not be as effective, but they will at least help. The general recommendation for temperature is that it should be no higher than 70 degrees Farenheit and the RH should stay between 30% and 50%. Generally, the lower the temperature, the better. It’s also important to continually record the temperature and RH. This helps to keep track of the collection conditions and will indicate whether the climate control equipment is working properly (Northeast Document Conservation Center).

 Another condition to focus on is the lighting of a collection.  Photographs are especially sensitive to light and if they are exposed for too long they will easily fade out or change colors, making them impossible to view over time. Visible light levels are measured in lux (lumens per square meter). The generally accepted visible light levels for sensitive materials has been 55 lux, but in more recent years this has been debated more frequently.  One of the most damaging light rays is ultraviolet radiation because of its high levels of energy.  UV light can be found in various lamps including fluorescent lamps which are commonly used indoors.  To help protect materials, filters made of special plastics can be used to cover windows and fluorescent tubes can be covered with sleeves in areas where the collection is exposed. An alternative is to use special low-UV fluorescent tubes.  If materials are being displayed for exhibition they should only be displayed for a brief time in order to limit their exposure to light (NDCC).

One last major factor to consider is the air quality of the collection environment.  I think this is an area that is often not focused on, but is just as important to maintaining a stable preservation environment. Pollutants can easily harm archival materials if they are not kept in check. The two major types are gases and particulates. Gaseous contaminants such as sulfur dioxide, nitrogen oxides, peroxides, and ozone can catalyze chemical reactions and form acid on materials. This is especially harmful for paper because it is so vulnerable. That is why so many archival storage materials are now made acid-free. But unfortunately for old photographs, they don’t have this luxury, so it’s crucial to store them carefully. Particulates such as soot or dust can also disfigure materials so photographs need to be kept covered from these threats. Controlling air quality is not easy to do and it depends on where the collection is stored. Archivists should try to make sure there is good air circulation in a collection storage space and replacement air should be as clean as possible. Air intake vents should not be placed near sources of heavy pollution, such as loading docks. Exterior windows should be kept closed. More recently, newer archival-quality enclosures have been created that help decrease the effects of pollutants. They are made with molecular traps that capture pollutants. Origins of pollution should also be reduced as much as possible. These include photocopying machines, construction materials, paints, sealants, display materials, cleaning compounds, furniture, and carpeting (NDCC). 

These are some of the more important components to maintain for a healthy preservation environment. If these are kept under control, it will contribute to photographic materials lasting much longer. Though it is sometimes difficult to maintain this environment for smaller archives that don’t have as much funding, they should still be aware of the best practices for creating a stable collection storage space. 

Sources:

"The Environment 2.1 Temperature, Relative Humidity, Light, and Air Quality: Basic Guidelines for Preservation." Northeast Document Conservation Center.

"Specifying Storage Environments in Libraries and Archives." Image Permanence Institute. Sept. 2008. Web.