by Tim Padfield David Erhardt and Walter Hopwood


As air pollution in cities diminishes, or at least changes its nature, the air pollution generated within buildings becomes a relatively more serious cause of deterioration. The low rainfall indoors allows hygroscopic salts to develop and remain, without ever being washed away. Nearly airtight enclosure brings the threat of damage by modern materials outgassing into the air around museum objects, as well as chemicals given off by self-destructive objects. The commonest indoor pollutants are acid gases from the decomposition of wood, cellulose acetate and cellulose nitrate. Acid attack requires a thin watery film on the surface of the object to allow ionic processes to occur. Within showcases, there is competition between absorption on the object, absorption on a sacrificial absorber and ventilation out through imperfections in the seal.

This is an illustrated version of the paper published as: Tim Padfield, David Erhardt and Walter Hopwood, 'Trouble in Store', in N.S.Brommelle and Garry Thomson, editors, 'Science and Technology in the service of Conservation', Preprints of the Washington D.C. Congress of the International Institute for Conservation, 1982, 24--27.

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