Mitteilungen des Österreichischen Staatsarchivs 39. (1986)
Archive Buildings and the Conservation of Archival Material. An Expert Meeting, held in Vienna, Austria October 30 - November 1, 1985 - THOMAS, David: Architectural Design and Technical Equipment for the Physical Protection and Conservation of Documents
234 Archive Buildings 1979 Lionel Bell threw a bucket of cold water on this approach when he wrote: ‘In practical terms, however, archives buildings are put up on sites that authorities are prepared to offer and it seems that the cost of and competition for them are the really significant factors. Negotiations in this respect therefore are political rather than professional’3). Despite Bell’s pessimism, or realism, the choice of a site plays a major part in facilitating the survival of records and the success of an archival institution. 2 The control of relative humidity and to a lesser extent temperature is a vital element in ensuring the survival of records. The minimum level for relative humidity (RH) is determined by the risk of cracking of fibres and embrittlement. This becomes a danger for parchment and leather bindings at 40-45%; paper is also more liable to break at these levels. The upper limit is the level at which mould will grow; this is between 65 and 70%. So the safe range is above 45% and below 65%4). The actual limits for individual countries will fall within this range but will be influenced by local climatic conditions. In the tropics an RH of 65% should be aimed for; any attempt to achieve drier conditions would lead to excessive expenditure on air-conditioning. In Europe, a range of 50-55% should be easily achievable. Published figures for RH used by archives in different climatic zones tend to reflect this need to maintain a reasonable equilibrium with local conditions. Thus, in Malaysia and Singapore which have a humid climate, a range of 50—65% is reported5). The USA has a totally different climate: the winters tend to be dry and the indoor RH is even lower because of the effect of heating. As a result American archivists find a range of 47% ±2% acceptable6). In Britain conditions of 55-65% are recommended; this is partly a reflection of local climatic conditions and partly because British archives hold a high proportion of parchment which survives better in more humid conditions. The only areas in the world in which it does not appear possible to maintain RH within the range 45-65% are Canada, the northern USA and north-eastern Europe. Here the winters are so severe that considerable heating is required and it may not always be possible to raise the indoor RH above 45% without damaging the structure of the building. The problem is that moisture added to the air would tend to move into the walls where it would freeze and cause cracking7). The control of temperature is important partly because of the influence it has on RH (RH falls proportionally as temperature rises) and partly because as 3) Lionel Bell The Archivist and his Accomodation in Archivaria 8 (1979) 83. 4) Garry Thomson The Museum Environment (London 1978) 85. 5) Yash Pal Kathp alia Conservation and Preservation of Archives in Unesco Journal of Information Science, Librarianship and Archives Administration 8 (1982) 97. 6) M. L. Ritzenhalter Archives and Manuscripts: Conservation (Chicago 1983) 30. 7) Thomson The Museum Environment 113; K. J. Macleod Relative Humidity, its Importance, Measurement and Control in Museums in Canadian Conservation Institute, Technical Bulletin 1 (1975) 7-8.
