Photographs

Storing photographs

Adverse storage conditions affect all items in a collection. The effects are not always dramatically obvious. Changes occur gradually over a long period of time. However, once the changes have occurred they are often irreversible, or involve complex and costly treatment.

A good storage environment can prevent physical damage, help slow down chemical deterioration, and greatly increase the life of photographs. The following sections outline:

• the ideal conditions for storing photographs;

• general storage guidelines;

• the best materials to use for storing photographs;

• practical steps you can take to improve your photographic storage, even when conditions are not ideal; and

• some easy, do-it-yourself methods for storing photographs.

Ideal conditions for storing photographs

Ideally, photographs should be stored in an environment where:

Temperature is kept low. The level recommended by Kodak for storing 19th century photographs is 15ºC. As this is difficult to achieve at home and in most working environments, a more realistic level has been set at 18ºC. Daily fluctuations in temperature should be no more than 4ºC. In some areas, this is extremely difficult to achieve.

Relative humidity is in the moderate range of 30–50%RH. The control of relative humidity is very important when storing photographs. Within the 30–50%RH range, conditions are dry enough to inhibit chemical reactions and the growth of mould; but it is also moist enough for paper and photographic emulsions to remain flexible.

Fluctuations in relative humidity should be kept to a minimum. This is important because the paper and emulsion components of photographs react at different rates to changes in relative humidity.

With extremes or rapid fluctuations in relative humidity, the paper and gelatine layers can pull away from one another.

This print has curled because the paper and the emulsion lose moisture at different rates. The gelatine has shrunk faster than the paper and pulled it into a curled position. Photograph courtesy of Artlab Australia

Light is kept to a minimum. Light is required only when the photographs must be viewed: for example, when they are on display, being accessioned or being used for research. Information about appropriate lighting levels are given in the section Ideal Conditions for the Display of Photographs.

Photographs are protected from pollutants, dust and insects.

General storage guidelines

Careful consideration should be given to the storage site and the storage systems. In situations where you are can achieve the ideal conditions, a good storage system in an appropriate storage site gives added protection to your collection. If the available facilities or the local climate make it difficult for you to achieve the ideal conditions, the selection of the storage site and the storage system you use become even more critical in preventing damage to the collections.

The following notes are guidelines for selecting storage sites, and outline the principles to be followed for protecting your collections in storage.

The storage site should be in a central area of the building where it is buffered from the extremes of climatic fluctuations which can occur near external walls, in basements and in attics. Don't store photographs in sheds.

The storage site should not have any water, drain or steam pipes, particularly at ceiling level. Leaking pipes can cause a lot of damage. Storage systems should be easy to use and accessible. Ease of use and accessibility usually mean that things will get less damaged during handling. Frustration with a difficult system can lead to damage.

Standard-size photographs, glass negatives and magic lantern slides should be stored vertically. This makes sorting through the collection to find things much easier than if they are stacked one on top of the other. It also avoids the situation where one photograph has to carry the weight of those stacked on top of it.

Flat storage is preferred for larger photographs because they don't have the rigidity to support their own weight in vertical storage. If they are stored vertically they will tend to bow.

Dividers or secondary boxes should be placed within storage boxes or filing cabinets. Dividers reduce the movement of items within the storage system, and provide additional support to the stored items.

Layers of storage should be provided. This gives maximum protection from:

• fluctuations in relative humidity and temperature. This is especially important in areas where the ideal levels of relative humidity and temperature cannot be achieved—the multiple layers of storage act as a buffer zone between the photographs and the extreme or fluctuating conditions;

• dust, pollutants and insects; and

• the damaging effects of light.

Each photograph should have its own protective wrapper or enclosure to protect it. Further layers of protection should be provided. Individually wrapped photographs should be boxed.

Labels should be provided on the outside of storage and housing systems, so that items can be located easily without having to search through and inspect every similar item.

A protective four-flap wrapper for photographs. Photograph courtesy of Artlab Australia

The best materials to use for storing and displaying photographs

There are many materials which provide a very safe and protective storage environment for photographs. There are also materials which should not be used because they can accelerate the deterioration of photographs. The list below summarises the good and bad materials.

Wrappers, enclosures and mounts—anything which is in direct contact with the photographs—should be made from materials which are chemically inert, that is, they will not cause chemical damage to the photograph. Nor should the wrappers, enclosures and mounts cause physical damage.

Preferred papers and boards for photographic storage are those made from cotton or linen, or wood-pulp papers which have been treated to remove harmful chemicals. These papers are considered to be photographic-quality storage papers, and are available from conservation material suppliers. Research shows that papers containing alkaline buffering, which are used widely for storing archives and works of art on paper, should not be in direct contact with photographs, but can be used for outer storage layers.

Plastics used widely for photographic storage are archival-quality polyester films such as Mylar D and polypropylene. Mylar is clearer and offers more support to the photographs than polypropylene. Polypropylene is cheaper and readily available. Copysafe sleeves are suitable polypropylene enclosures. Tyvek, a spun, bonded polyethylene is also suitable for wrappers for photographs.

Abrasion is a major problem for photographic emulsions, especially for gelatine. Therefore, the material which is in direct contact with the emulsion must be very smooth and slick, like the surface of the photograph. An already abraded photographic emulsion will abrade Mylar and photographic storage paper.

Boxes should be made from good-quality materials. If non-archival boxes are to be used they should be lined with a good-quality paper or board.

Ideally, storage furniture should be metal, with a baked enamel finish. Wood gives out active chemicals, sometimes for many years. Wood polishes and varnishes also contain substances which can damage photographs.

Materials to avoid are:

• poor-quality papers. Many poor-quality papers become acidic over time. Acids attack the paper fibres, causing the paper to become brittle and crumbly. Acids from these papers can migrate to the photographs and cause damage to the emulsion, the photographic image and the paper base. Ordinary cardboard boxes and film boxes are not recommended for storing photographs for the same reasons;

• sulphur-containing materials. Remember that sulphur tarnishes silver, and photographs are silver-based. Avoid any papers and boards which may contain sulphur. Even good-quality wood-pulp papers contain sulphur. Black dyes used to colour black paper often contain sulphur. Rubber cements and rubber bands also contain sulphur and should be avoided; and

• plastics. Never store photographs in plastics such as polyvinyl chloride—PVC. The PVC in folders and storage sleeves breaks down in the presence of atmospheric moisture, to produce hydrochloric acid. This is a strong acid which will cause irreversible damage to your collections.