Working with Collections : What is Preservation?

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Preservation of collections is the extension of the useful life of collections by preventing deterioration.

The external causes of deterioration:

• Poor handling or storage
• Light
• Incorrect temperature and relative humidity
• Pollution
• Pests
• Fire and flood
• Theft or vandalism

These causes can work together, eg. a high relative humidity can increase pest attack and poor storage may increase the risk of fire and flood damage. How these factors affect collections depends very much on what individual objects are made of. Most Burns related material such as the many books and manuscripts, furniture, and fine art, are made from organic (carbon based) material meaning a greater risk from most of the causes of deterioration listed above. Added to this inherent risk is the popularity of Burns and the tendency to expose artefacts to unremitting damage whilst on display.

Handling and Storage

Objects are most likely to be damaged when they are being handled or moved—no matter what the distance. Physical damage is the most common form of damage to any artifact and is often the most preventable. The following tips:

1. Don't rush
2. Be organised and plan ahead
3. Provide support and protection to your objects
4. Note any damage that occurs during the move

Light

Although we could not do without light in museums, galleries and libraries, it is important to remember light is an environmental factor that contributes to the deterioration of our valued collections.

It is vital to be aware that visible light is often accompanied by:

• UV radiation, which can cause more damage faster than visible light; and
• infrared radiation, which heats materials.

When light and UV radiation fall on an object, they deliver bundles of energy to that object.

As a result, various chemical reactions can take place, depending on the amount of energy delivered. These reactions are called photochemical reactions. In some cases it is very easy to see the effects of these reactions: try leaving a piece of newsprint in the sun for a few hours and examine the results. The paper becomes discoloured and yellowed. It often feels different as a result. However, most changes caused by photochemical reactions are not as quick as this nor as obvious; so it is difficult to know they are occurring. Nevertheless their effects can be devastating and ongoing.

Light causes extreme and irreversible damage to many materials, most notably organic materials—those that derive from plants and animals. In a museum, gallery or library, these will include furniture, textiles, prints, books, drawings, manuscripts, wallpaper, dyes and inks, feathers and fur.

For example, UV radiation and visible light:

• set off chemical changes in paper and textiles, which weaken and discolour them; and
• cause inks, dyes and pigments to fade, and so seriously affect the aesthetic quality of many items.

Infrared radiation is less energetic than UV radiation and visible light. It:

• heats materials and can cause them to expand, leading to mechanical stresses; and
• can also cause chemical changes to progress more rapidly. As a result, infrared radiation can increase the destructive effects of visible light and ultraviolet radiation.

Monitoring and control: for this you’ll need a light meter to test light levels at different locations within your venue and at different times of the day.

Incorrect temperature and relative humidity

The wetness or dryness of air is not only dependent upon the amount of water in the atmosphere, but also on the capacity of the air to hold water. Air can hold more water at higher temperatures which accounts for the rapidity of decay in hot and steamy jungles compared to the cool, dry conditions of, say, the inside of a household fridge.

Therefore, increasing the temperature in a room will normally reduce the relative humidity whilst lowering the temperature has the opposite effect and making the air feel wetter.

Since most pests thrive when they have both a food and water source, relative humidity and temperature are two of the most important environmental factors which can contribute to the deterioration of our valued collections.

Extremes of temperature and relative humidity — and rapid fluctuations in these — can lead to a range of problems. The risks of physical damage, such as warping, cracking and splitting, chemical deterioration, and insect or mould attack are all increased when temperature and relative humidity are too high or too low.

Monitoring and control: a thermohygrograph records the relationship between the relative humidity and the temperature. This will let us know changes in RH and temperature over time and indicate the wetness or dryness your artefacts will experience at microscopic level. RH and temperature recording devices come in a variety of forms from the clockwork cylinder thermohygrograph to modern dataloggers. Equally, controlling RH and temperature can vary from a combination of central heating and silica gel (a water-loving substance that can remove moisture from the air) to automatic air exchange unit, humidifiers and dehumidifiers.

Pollution

Dust, pollutant gases, and emissions from display and storage materials can add to the degradation of materials by encouraging biological or chemical damage. Dust, an aggregation of human skin, hair and assorted waste, provides a foodstuff for insects and can lead to chemical attack. Similarly, pollutants such as acidic gases (eg. sulphur dioxide), formaldehyde from furniture glues, or acidic emissions from case felting - or even degradation from materials within a particular object - can promote chemical reactions harmful to the surface of artefacts.

Commonsense approaches

While some options for controlling pollution require expert advice and financial outlay, there are a number of options which offer protection with little cost and effort. For example:

• use display cases and layers of storage to provide a protective local environment for the object;
• frame and glaze artworks which are on display;
• provide dust jackets for books;
• place flat paper-based objects in Solander boxes;
• provide archival-quality boxes for fragile or susceptible objects; and
• cover large objects which will not fit in storage cases or boxes with appropriate sheeting, for example, unbleached and undyed cotton or linen, or Tyvek, when they are not on display.

Various monitors

There are a wide range of specialist monitors and detectors on the market. Consult the conservation equipment suppliers listed in the ‘opportunities for action’ below.

pH indicator strips

pH indicator strips are used to determine whether acidic gas is being produced in an area. When moistened with neutral pH distilled water, the strips absorb gases from the air and indicate whether acids are formed.

Leave the moist pH strip in the air for 15-30 minutes, and monitor any colour changes against the reference chart on the indicator strip case.

pH indicator strips are a guide only, so further testing should be done.

Check with experts

Your local authority offices have information about environmental pollution in your area, and may be able to help you contact local experts.

Pests

If they are not controlled, insects and moulds can severely damage many types of organic materials in our collections. Controlling them can be much more complicated than just buying a can of insecticide or calling a pest control company. Chemical warfare on insects and moulds can have very serious effects on humans. Many of the chemicals used are toxic—that's why they kill insects and moulds. These chemicals can also damage objects in collections.

It is important, therefore, to be able to recognise the signs of insect and moulds activity—and these can sometimes be very subtle. It is also important to know which biological pests pose a threat, so that you can take steps to control them, but without placing your collections or yourselves at risk.

Insect identification is therefore the first step in addressing the reasons for infestation and targeting the cause. The following should only be carried out once pest identification has taken and specialist advice on the suitability of each measure for your particular collection:

• use of low temperatures;
• fumigation using controlled atmospheres;
• use of sticky traps;
• biological control the use of parasites and predators; and
• use of some of the new-age pesticides, for example, insect-growth regulators and pheromones, to control insect pests.

Integrated Pest Management

• Formulation of an integrated pest management plan tackles the threat of pest attack holistically.
• Make the environment undesirable to pests by:

• physical exclusion;
• physical removal/vacuuming;
• good housekeeping;
• maintaining good environmental conditions; and
• applying chemicals as required.

Monitor the area by:

• inspecting the area regularly; and
• placing and inspecting insect traps.

Fire and Flood

The potential effects of a fire or flood can be catastrophic. In common with all other threats to collections, assessing fire and flood risks and taking action to reduce these risks should form the basis for an integrated disaster plan. For a useful compendium of basic information (conveyed primarily through summary checklists) on disaster prevention, response, and recovery: Anderson, Hazel, and John E. McIntyre. Planning Manual for Disaster Control in Scottish Libraries & Record Offices. Edinburgh: National Library of Scotland, 1985.

Theft or vandalism

The risk from physical interference or theft is a very real threat to the integrity of objects. Various guides exist which allow you to assess the security requirements of your collection. This guide provides a checklist when considering the type of security measures needed for a museum, archive, historic library or archive:

MLA Guide to Assessing the Security Requirements for Museums and Galleries