Biological Principles of Book Keeping Conditions

Temperature and humidity conditions are most important for book preservation. To protect books against the attack by fungi, it is first of all necessary to be guided by the physiology of these organisms and the properties of paper associated with the aqueous regime of the medium. The susceptibility of paper to the attack by fungi is dependent on the lower limit of relative air humidity at which destruction begins and the rate and length of the process development. The limiting values of humidity and temperature for spore germination and colonisation of fungi on cellulose materials' ' ' ' ' 6 have long been found. The spores of many fungi most often germinate at a relative air humidity of 80-100 %. However, in the case of long-term storage the materials revealed spore germination of the Aspergillus and Penicillium at 70-75 % and even 60 % relative air humidity. Fungal growth results in the beginning of moisture liberation. The destruction of fibres leads to the fact that more than half of the cellulose remains in the material in the form of water: during decompositon of l g of cellulose, 0.55 g of water is freed. The accumulation of water by a colony makes it become independent of the relative air humidity. Therefore, the importance of the moisture condition which is crucial for spore germination is somewhat weakened during subsequent growth of fungi. The viability of fungi in book stacks is, in turn, dependent on changes in the moisture content of paper which is the base and nutrition substrate for their growth. Paper is a very complex hygroscopic system with inhomogeneous capillary properties' . Depending on the kind and method of fibre treatment, amount and quality of adhesives and fillers, mode of making and drying, art of coating, and the conditions of use the ultimate moisture content of paper and its changes are established. The role of ingredients in paper composition may briefly be characterized as follows. Cellulose, especially native wood cellulose, is a more hygroscopic product than pearl fillers; therefore, the higher the ash content of paper, the less the moisture capacity. The content of hemicelluloses in wood pulp and wood cellulose also contributes to high hygroscopic capacity. This is why daily paper (with wood pulp content equal to 60-80 %) has a much higher