Conservation of cultural objects in museums and libraries
Archaeological objects are often saturated with water when they are recovered, for example from damp soil, bodies of water, sunken ships and so on.
Historical documents in archives or museums frequently become soaked with water from burst pipes, flooding or fire.
To protect these objects against fungal growth and resulting damage, they are first frozen in freezing chambers or by other means. Afterwards they can be freeze dried bit by bit in special drying systems. This virtually eliminates harmful effects, such as corrosion of metallic parts or, in the case of documents, washing out of the ink, sticking together of individual pages, or leaching of printing ink. As a result, the documents remain legible. Sublimation is accelerated by energy input from heated shelves and a vacuum level near the triple point of water, such as 3 hPa. The drying times range from several days to a few weeks due to the thickness of the objects.