are internationally accepted standards for microfilm. Film also has a proven lifespan of 500 years and can be read in an emergency with nothing more sophisticated than a lens or a hand held viewer. In that regard, preservation microfilming has quietly maintained its status as a highly valued and widely practiced preservation reformatting strategy amidst the bells and whistles of the digital revolution (Ogden 1999).
To a large extent, microfilming has proven to be an effective technology for rescuing brittle paper and for facilitating shared access to endangered research materials. Until feasible solutions to preserving long-term access to digital documents are developed, microfilming will remain the most appropriate preservation strategy for archivists, especially, in the developing countries where expensive digitisation projects are impeded by scarce resources and scant research in digital preservation. Presently, digital conversion seems to be only attractive in terms of enhancing access to documents.
Hazen, Horrell and Merrill-Oldham (1998:14), and Menne-Haritz and Brubach (1999) acknowledged that the use of microfilm for preservation and digital imaging for improving access, or what Chapman, Conway and Kenney (1999) called the hybrid approach, is the only way of benefiting from the relative advantages offered by both technologies. For that reason, microforms and digital objects are used hand in hand in the UK to enhance access to archival materials as well as ensuring their continued survival (Feather & Eden 1997:17; Shenton 2000).
Although reformatting can facilitate long-term access to documental)' materials, preventive care for records and archives encompassing proper storage, handling, and security are some of the strategies that can tremendously reduce the need to reformat them.
\ of materials. Most environmental factors, which initiate the degradation mechanisms of documents, can be managed. The environment in storage areas is crucial to the preservation of records and archives.
Environmen~l factors such as biological agents, temperature, relative humidity (RH), air pollution, dirt, and light can contribute to the deterioration of documentary materials (Cunha
& Cunha 1983:10; 62-63; Hodson 1972:91-106; Jones & Ritzenthaler 1988:188; Kufa
1997:159; Ritzenthaler 1993:45; Swartzburg 1995:77; UNESCO 2000). The control of environmental factors has a positive impact on controlling biological factors such as mould, silverfish and other biological enemies of records and archives. The factors that can accelerate the deterioration of records and archival materials are discussed in more detail in the subsequent subsections.
2.8.1 Temperature and relative humidity
The maintenance of proper temperature and relative humidity (RH) in records storage areas is very important. According to Ogden (1996b) control of temperature and relative humidity is of critical importance in the preservation of documentary materials because they contribute significantly to the deterioration of materials. Although, there are no agreed standards for temperature and RH in storage and use areas, there is consensus within the preservation community that lower temperatures and a lower relative humidity greatly extend the life expectancy of documentary materials (Adcock. n. d; Patkus 1998:73). The wrong environment can doom archival collections to a very short life span. Therefore, control of temperature and RH levels should be the cornerstone of any responsible preservation programme (Shahani, Hengemihle & Weberg 1995 :61; Williams 2000:32).
The combination of high temperature and high humidity hastens the chemical deterioration of materials. These factors also playa major role in the multiplication of some of the biological agents discussed in section 2.8.4 below. Relative humidity represents "the amount of moisture in the air relative to the amount the air is capable of holding, expressed as a percentage"
(Appelbaum 1991 :25). On the other hand, temperature, which is the degree of hotness or coldness of an object, is expressed in degrees Celsius (OC) or Fahrenheit eF). It is important to realize that temperature and RH are interrelated; a change in one will bring about a change in
the other. The rate of most chemical reactions is approximately doubled with each increase in temperature of 18°F (10°C) (Adcock. n. d; Shahani, Hengemihle & Weberg 1995:61). High relative humidity provides the moisture necessary to promote harmful chemical reactions in materials and, in combination with high temperature, encourages mould growth and insect activity. Extremely low relative humidity may lead to desiccation and embrittlement of certain materials.
It has been argued that the level of RH and temperature that is ideal for preserving materials varies from format to format (Ritzenthaler 1993 :46). However, studies have shown that most paper-based materials stored at 22° C and 50% RH would have an approximate lifetime of33 years, but if the temperature were lowered to 16° C and the humidity to 40%, such materials would have a lifetime of 88 years (Reilly, Nishimura & Zinn 1995 :7). Similarly, if materials were to be subjected to high temperatures and humidities (such as 28° C and 75% RH) noticeable deterioration would occur in nine years or less. Furthermore, Reilly and Nishimura and Zinn (1995:7) demonstrated that if temperature and RH were kept at either 14°C and 50%
RH or 16° C and 35% RH the materials would have a lifetime of close to 100 years.
Maintaining stable conditions is of great importance (frinkaus-Randall 1998: 105; Ritzenthaler 1993:51). In essence, temperature and relative humidity should not be allowed to fluctuate.
Research done at the Library of Congress has shown that chemical deterioration of paper proceeds more quickly if paper is exposed to temperature fluctuations than if it is stored at a constant temperature (Reilly, Nishimura & Zinn 1995: 20). Though authorities like Erhardt and others (1995), Lull (1995), McCrady (1994), Peters (2000:5) and Real (1995) disagree on the ideal temperature and relative humidity for records and archival materials a frequent recommendation is a stable temperature no higher than 70°Fahrenheit or 21°Celsius and a stable relative humidity between a minimum 000% and a maximum of50%.9
The ultimate consideration should be informed by the need to maintain a "thermodynamic equilibrium by optimally preparing or conditioning the air" in which documents are stored and 9 Erhardt and others, and McCrady's articles provide an overview of the Smithsonian Conservation Analytical Laboratory research on climate control, while the others question recommendations made by a Smithsonian press release describing the research. For further discussion of the controversy, see WAAC Newsletter (September 1996).
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in which they are consulted (Stehkamper 1988:164). However, controlling climate conditions, such as temperature and relative humidity, is a much more difficult task. Installing heating, ventilation, and air conditioning (HV AC) systems and monitoring the weather can aid in controlling the climate.
Installation of adequate climate controls and operation of them to maintain preselVation standards will retard the deterioration of materials considerably. Climate control equipment ranges in complexity from a simple room air conditioner, humidifier, and/or dehumidifier to a central, building-wide system that filters, cools, heats, humidifies, and dehumidifies the air (patkus 1999a).
However, climate control equipment tends to break down and the energy resources to keep an air-conditioning system running are prohibitive for most countries in sub Saharan Africa.
Instead, some authorities such as Briggs (1994), Giovannini (2000), Gut and Ackerknecht (1993), Harris (1993) and Rowoldt (1993; 1998) advocate the design of climate responsive buildings. The buildings would have 'natural' methods of air-conditioning in order to reduce the installation, energy and maintenance costs. Therefore, the suggested model advocates buildings that should be structurally designed in such a way that their makeup would control heat and solar radiation, and regulate air circulation without the use of artificial means such as air-conditioning.
In other words, archival buildings should exploit structural rather than artificial means to control the environment. Air-conditioning cannot be relied upon as it can breakdown and electricity supplies to power the equipment might not be always available. In fact, a survey carried out by Mazikana (1997) showed that air conditioning systems at most archival institutions in Africa had broken down and had gone unattended to due to shortage of foreign currency to procure spares. In another sUlVey carried out in Africa, Coates (2000) discovered that only 15% of the pwpose-built buildings had air-conditioning. Air-conditioning might be the answer to controlling the climatic conditions that affect records and archives, but it expensive to install and maintain.
According to Hadgraft (1994:47) and Briggs (1994:49) all air-conditioning systems have an in-built obsolescence with a life of about ten to twelve years. Many archival institutions in the developing world can least afford maintenance and replacement costs, given their meagre resources and foreign currency constraints. A few years back, the National Archives of Zimbabwe and the National Film and Sound Archive of South Africa went without an operable air-conditioning system for about five years due to poor maintenance and lack of spare parts.
While the natural means of preservation as opposed to artificial means seem to hold the most promise for the preservation of the archival heritage the problem is that most buildings where records and archives are presently housed were designed without taking climatic controls into considerations. For now, we will have to live with the problem of controlling temperature and relative humidity because any attempts to redesign them would be very prohibitive in terms of costs. The issue of the design of archival buildings is further dealt with in sections 2.8.5.1 below and 3.3.3 in Chapter Three.
Additional measures that can be taken to control temperature and relative humidity include adequate maintenance on buildings. Keeping doors and windows closed to prevent exchange of unconditioned outside air. Removing of holdings from attics, which tend to be hot, and basements, which can be damp, can lessen the deterioration of materials due to climatic conditions. Archives and records may also be protected from moderate fluctuations by acid free archival boxes.
Monitoring of temperature and RH is essential to the success of climate control. Frequent checking of temperature and RH is very important in equatorial, sub-equatorial, tropical and monsoon climates because the warm and damp conditions present special problems for the preservation of documents (Duchein 1977:134). Many of the problems associated with protecting records and archives against temperature, RH and biological factors apply acutely to these climates. Monitoring can be achieved through the use of measuring instruments and records and archives personnel. Monitoring can either provide data to show that current climate control is inadequate or guard against any environmental extremes that might occur.
Some of the instruments used for monitoring temperature and RH are summarized in Table Two.
Table 2: Instruments for measuring relative humidity (RH) and temperaturelO
Instruments Temperature RH Remarks
Thermometers Yes No Provide accurate temperature
Hygrometers No Yes Not recommended because they can be very inaccurate and most cannot be recalibrated
Humidity indicator No Yes Provide only approximate readings strips
Psychrometers Yes Yes Accuracy depends on the design of the calibration instrument and the skill of the user
H ygrothermographs Yes Yes Standard choice for monitoring temperature and RH
Dataloggers Yes Yes Data is transferred between the datalogger and a personal computer that does data analysis
All the measuring instruments enumerated m Table Two exceptmg hygrothermographs and dataloggers cost very little. Thermometers, hygrometers and psychrometers provide a snapshot of current conditions rather than an ongoing record (patkus 1998:73). Notwithstanding cost considerations institutions can choose between hygrothermographs and dataloggers since they are reliable instruments of measurement (patkus 1999a). Although dataloggers have an advantage over hygrothermographs in terms of having the ability to electronically analyse data, hygrothermographs are more recommended (patkus 1999a).
A datalogger does not provide continuous monitoring m the way that a recording hygrothermograph does. Most loggers can take measurements at intervals ranging from a few seconds to a few hours as more frequent measurements will occupy more memory and require more frequent downloading of data. In addition, some loggers use sensors that have a ''time- lag" of four or five minutes. If the humidity were falling, this would be a disadvantage ifvery frequent sampling were required.
10 Tables that are not attributed to any particular sources were constructed by the author of the thesis from data gathered from a variety of information sources and the information was not originally in table format.
Monitoring environmental conditions largely depends on people rather than automatic recording instruments. Therefore an effective monitoring programme will depend on a written plan for collecting information and maintaining instruments by people assigned the monitoring responsibility in the institution. The plan should identify areas to be monitored, the procedures to be adopted, and forms for recording needed information (patkus 1998:74).
The recently developed Preservation Calculator, a tool for managtng the environment developed by the Image Institute in Rochester, New York is going to ease problems of monitoring the climate (Image Permanence Institute 2002; The National Archives of the Netherlands et al. 2001:97). Interpreting temperature and RH data from a large table ofRH and temperature data, or from a series of hygrothermograph charts is extremely difficult (Reilly, Nishimura & Zinn 1995:4). However, the Preservation Calculator makes it possible to quantify the result of changes in climate control equipment, that is, modifications of the HV AC systems, the addition of room air conditioners or dehumidifiers, and changes in air circulation. The Preservation Calculator is illustrated in Figure Two below.
Figure 2: Sample Preservation Calculator
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