Some changes to objects are sudden, such as the breaking of a ceramic by dropping, and some are gradual, as with the fading of pigment or dyes on a painting or tapestry. Changes may have occurred before an object came into the collection. These may be intentional, such as the bending or breaking of a sword as an offering, or purely accidental, as when something is dropped leading to cracking or denting.
Or changes may simply occur a result of neglect, for instance when dust gathers over a period of time, compacting and eventually binding onto the surface of an object. Sometimes changes become valued in their own right. This can happen when a repair is made at the time of use and which is later preserved as evidence of its previous context and value to a society.
Most objects are made from two types of materials:
- organic – these are carbon based and come from a previously living plant or animal such as wood, paper, textiles, ivory, bone or leather
- inorganic – these are made from earth elements such as ceramic, stone, glass, metal or enamel.
We now have a third type:
- synthetic materials that are man-made.
All obejcts are subject to the processes of change and deterioration because the materials of which they are composed are affected to differing degrees by the agents of decay. Conservation cannot halt the deterioration of objects altogether, but there are many ways to limit and reduce the rate of the process. When we know the causes of decay we can attempt to limit further decline using preventive measures. All conservation methods make changes to an object, however, so interventive treatment is carefully thought through before proceeding.