... itself are preserved only in the corrosion layer." * The removal of concretion may take place either on site or at the conservation laboratory. * In the case of the former some concretion removal may have to be done on site. There are two reasons for this: 1. if these artifacts have to be stored for weeks, before conservation commences it is much easier and safer to separate the wide variety of concreted artifacts which are made from different materials. Very often different metals in an electrolyte solution such as sea water cause a chemical-electrical reaction, which corrodes the metal. 2. Secondly it is also much cheaper to transport smaller items than a large concreted block. On the other hand concretions can also serve as a protection to the artifact, in the case of cast iron cannons the concretion protects it from physical and chemical damage during transportation from the wreck to the conservation ...

See this essay or coursework document in full right now