Deterioration of Documents

DEFINITION A change of original state of any material through the interaction between the object and factors of destruction.

Relating to Documents: Any form of degradation or reduction in the quality or usable life of a document resulting from its inherent qualities or interaction with destructive elements in the environment.

Process of Document Deterioration Most documents are made of organic materials which undergo natural ageing. Natural ageing is a slow but inevitable process.

Natural ageing cannot be stopped Natural ageing cannot be stopped. The rate of natural ageing can however be slowed down.

Rate of Document Deterioration. Depends On: Chemical Stability of the document Environment Storage Conditions Handling Procedures

The environmental factors/elements that can influence the rate of document deterioration include: Temperature Humidity Light (Radiant Energy) Pollution

Biological Agents Disasters Fungi Insects Rodents Human beings Environmental factors continued… Biological Agents Fungi Insects Rodents Human beings Disasters

On their own, these factors can be dangerous to documents. But acting jointly, they can be deadly, resulting in rapid degradation of documents, ultimately resulting in total loss.

Types of Deterioration. Chemical Deterioration Biological Deterioration Physical Deterioration Deterioration through Disasters

Chemical Deterioration Chemical deterioration is document degradation which emanates from chemical activities ( reactions) which results in the introduction of various forms of acidic compounds into the fabric of the document – particularly paper documents.

Chemical Deterioration can result mainly from the following elements Temperature Humidity Light Pollution

Temperature Temperature is the degree of hotness or coldness of a body.

Temperature has impact on documentary materials in the following ways: At high temperatures, chemical reactions are speeded up ( For every 180 F increase in temperature, chemical activity in most substances double). Acid is introduced at a faster rate, hydrolysis takes place and documents get decomposed – they become brittle, craky and easily break at a touch.

2. Estimated that the useful life of a paper document is reduced by ½ (Half) with every 100 C increase in temperature. 3. At high temperature, film documents buckle at the edges, plastic base documents warp. 4. At high temperature, desiccation takes place.

5. Fluctuating temperatures (cycling) are worst for documents 5. Fluctuating temperatures (cycling) are worst for documents. They result in expansion and contraction – documents disintegrate easily.

Recommended Temperatures: Paper Documents – 200C ± 20C Film and Electronic Documents – 180C ± 20c These must be kept as close to constant as possible.

Control of Temperature Air Conditioning Good Ventilation

Monitoring Daily readings must be taken using a thermometer. Readings must be recorded and consolidated to determine trends.

Humidity Definition: The amount of moisture in a given volume of air at a given temperature.

Types. Absolute Humidity Ambient Humidity Relative Humidity

Effects Most chemical reactions are water (moisture) dependent. High Humidity and high temperature speed up chemical reaction. Low humidity results in the desiccation of paper.

A combination of high temperature and humidity encourage mold or mildew – fungus growth (65% RH+200C) High humidity and high temperature levels increase the likelihood of insect infestation. Under excessive humidity, water soluble inks smudge, feather or run.

Coated or glossy paper stick together. Normal paper – photocopy or printing paper became damp/soggy and adhere to each other. Film based documents get stuck to each other.

Fluctuations are even more dangerous – they cause internal stress and instability of the fibres of paper due to the contraction and expansion, thus breaking the bond to bond holding of the paper.

Controlling No easy solution. Because of the varied range of documentary materials which respond differently to humidity and temperature. Ideally, separate storage area should be used. This is not always the case because of the cost involved.

Theoretically the lower the humidity and temperature, the better Theoretically the lower the humidity and temperature, the better. But this is expensive to maintain particularly so since humidity levels increase with drops in temperature.

Ideal Control Control both temperature and humidity through air conditioning for 24hrs a day. Paper Doc. – 45% ±2% and 200C ± 2) Film + Digital Docs. -35% ± 2% (180C ± 2)

In the absence of air-conditioning facilities; Use Humidifiers and Dehumidifiers (Electronic/ Chemical). Windows should be widely opened to allow free circulation of air.

Heavy cotton curtains should be used – they absorb excess humidity at peaks and exude moisture at low times to ensure equilibrium. Wooden furniture could be used to absorb excess moisture.

Monitoring Measuring Instruments; Hygrometre Hygrothermograph Humidity Indicator Card Data Logger