Once objects are abandoned or lost, they often undergo deterioration as a result of exposure to climatic conditions, the type of soil they are buried in and conditions such as the rate at which they are buried, the proximity of other materials, compacting of the soil and leaching. For certain objects this deterioration is rapid and inevitably leads to their disappearance, while for others such change may gradually slow down and even stop. At this point, it is said that the object is in equilibrium with its environment.
The excavation of a site destroys this balance and the object to starts to deteriorate again, since it must once more adapt to new environmental conditions. This deterioration can be kept in check through the application of appropriate conservation measures, which sometimes consist simply of keeping dry things dry and wet things wet. Certain of these measures can be easily carried out by an archaeological team, meaning that the presence of a conservator in the field is not always essential. However, a conservator is called for when a fragile object must be consolidated before it can be removed or when perishable or unstable elements have to be preserved in situ.