Agents of deterioration

The 'ten agents of deterioration' are a conceptual framework developed by the Canadian Conservation Institute (CCI) used to categorise the major causes of change, loss or damage to cultural heritage objects (such as collections held by galleries, libraries, archives and museums).^[1] Also referred to as the 'agents of change', the framework was first developed in the late 1980s and early 1990s. The defined agents reflect and systematise the main chemical and physical deterioration pathways to which most physical material is subject. They are a major influence on the applied practice of conservation, restoration, and collection management, finding particular use in risk management for cultural heritage collections.

CCI defines ten 'agents': dissociation, fire, incorrect relative humidity, incorrect temperature, light and ultraviolet light, pests, pollutants (or contaminants), physical forces, thieves and vandals (at times referred to as 'criminals'), and water. The number of primary agents has remained the same since the 1994 with the addition of 'custodial neglect' (now termed dissociation), though the scope and names of some categories have been updated over time to reflect new research or thinking.

Each category may be further subcategorised as rare and/or catastrophic (Type 1), sporadic (Type 2), or constant/ongoing (Type 3), particularly when applied to risk assessments. For example, within the category of physical forces, an earthquake may be designated a Type 1 event; a handling accident where an object is dropped as Type 2, and ongoing physical wear from daily handling as Type 3.^[2]