The Conservation of Library Collections in Tropical and Sub-Tropical Conditions: The Problem of the Increased Dangers of Damage and Decay in Areas of High Temperature and Humidity

We shall restrict our consideration primarily to the biological dangers. The only chemical dangers that we shall consider are those which result from paper production. Chemical damage from the inks and colouring in books has no special features in tropical and sub-tropical conditions; it is not very frequent; so that to consider it separately would not contribute very much to my theme. Chemical damage from air-pollution does not represent a problem that is typical of tropical and sub-tropical climates; rather the contrary, for the areas of industrial concentration, where this danger exists, lie primarily still in the moderate climate zones of our world. According to the present state of knowledge, paper must be kept cool and dry if it is to remain usable over long periods. Dryness impedes microbiological infestation, coolness impedes rapid chemical decomposition. Various atmospheric levels are given in the technical literature: different levels for different kinds of paper. Old, animal or heavily surface sized paper can at 70% RH take up sufficient water to support the growth of mould spores (which are present everywhere in the air) at a temperature of 25° or 26° C. Modern, industrially produced paper will not grow mould even at these atmospheric levels, but it is much more subject to chemical