The Importance of Humidity Control in Archives

Solve Humidity Problems

A green New Zealand invariably means a wet New Zealand. Humidity and inappropriate amounts of water vapour constitutes a real threat to the continued preservation as once moisture damage, bacterial growth, corrosion has occurred the object to be preserved will probably never return to its former condition. . Temperature and pollutants are important factors in preserving documents. In general the humidity and temperature have to be as stable as possible and pollutants should be kept to a minimum. 

Organic Materials

Books in row.jpg

Whether you have a natural history specimen, textile, paper, book, manuscript, print or any other ethnographic (made from wood, leather or ivory) material, all such materials are subject to a natural process of decay. As they are all organically based they are susceptible to mould growth and rapid deterioration, particularly in a warm, moist environment. By removing the moisture from the environment the damaging effects can be eliminated when relative humidity is kept under control.

Film Storage

The long term storage of paper and film records needs very special conditions. For example old flammable nitrate film shrinks and decomposes with age and needs to be carefully copied onto modern safety film if it is to be preserved. Humidity is a key factor affecting acetate film degeneration. The optimum conditions required are 30% Relative Humidity at 20°C if the safety of the stored film is to be guaranteed. Extensive research work has shown that, without doubt, humidity is the most significant factor affecting acetate film degradation.


Ferrous and non-ferrous metals and alloys corrode rapidly in the presence of water vapour. Moreover, the rate of corrosion is further accelerated by natural or industrial pollutants in the air. Bronze, for example can develop the phenomenon known as ‘Bronze Disease’ breaking into active corrosion if relative humidity is too high. Metal which is already severely corroded may require the maintenance of a relative humidity below 40% but usually corrosive activity is significantly reduced below 60% RH.

Glass and Ceramics

The maintenance of precise relative humidity levels is, of course essential if 16th and 17th Venetian glass (circa 1676 to 1680) is to be displayed and stored safely. When the relative humidity is inappropriate, ‘weeping or crizzling’ occurs due to the reaction of unstable constituents of the glass with the water vapour in the air. Extensive research has ascertained that glass and ceramic objects are best protected in an environment where relative humidity is between 40% and 60%.


Air Solutions provides the solutions to this problem using desiccant dehumidifiers. Desiccant dehumidifiers are used world wide protect film, tapes, documents, books, and artifacts in archives, museums, and libraries. With dehumidification we physically remove the moisture from the air, meaning that corrosion and mould growth are unable to occur.

If you would like to find out how we can help with your application, please contact us or call (09) 5240543

Current Customers:
Auckland Art Gallery, Auckland Central Library, Auckland Museum, Museum of Wellington City and Sea, National Library of NZ, Nelson Museum, NZ Navy Museum, Puki Ariki Heritage Centre, Silverdale and Districs Historical Museum, South Canterbury Museum, TVNZ Avalon Studios, University of Auckland